WO2002006174A1 - Hydrophobic coating with dlc and fas on substrate - Google Patents

Abstract

A substrate is coated with a hydrophobic coating system including diamond-like carbon (DLC) and at least one fluoro-alkyl silane (FAS) compound. In certain embodiments, the coating system includes an FAS inclusive layer provided over at least one DLC inclusive layer in order to increase the initial contact angle of the coated article.

Description

HYDROPHOBIC COATING WITH DLC & FAS ON SUBSTRATE

This invention relates to a hydrophobic coating system including diamond-like

carbon (DLC) and at least one fluoro-alkyl silane (FAS) compound provided on (directly

or indirectiy) a substrate of glass, plastic, ceramic, or the like, and a method of making the

same. The coating system may include one or more layers, and the DLC portion of the

coating may be deposited on the substrate utilizing plasma ion beam deposition in certain

embodiments.

BACKGROUND OF THE INVENTION

. Conventional substrates (e.g., glass) are susceptible to retaining water on their

surfaces in many different environments, e.g., when used as automotive windows (e.g.

backlites, side windows, and/or windshields) or as architectural/residential windows.

When water is retained or collects on automotive windows, the water may freeze (i.e.

forming ice). Additionally, the more water retained on a windshield, the higher power wiper motor(s) and/or wiper blade(s) required.

Thus, there exists a need in the art for a coated article (e.g. coated glass, ceramic or

plastic substrate) that can repel water and/or dirt, and a method of making the same.

It is known to provide diamond like carbon (DLC) coatings on glass. U.S. Patent

No. 5,637,353, for example, states that DLC may be applied on glass. Unfortunately, the

DLC of the '353 patent would not be an efficient hydrophobic coating.

U.S. Patent No. 5,250,322 to Takahashi et al., discloses a water-repellant coating

including FAS on a glass substrate. Unfortunately, the water-repellant coatings of the

'322 patent may not be durable enough for certain applications (e.g., it may be prone to

scratching, breaking down, etc. in automotive and/or other harsh environments).

In view of the above, it is apparent that there further exists a need in the art for a

durable protective hydrophobic coating system that is somewhat resistant to scratching,

damage, or the like.

It is a purpose of different embodiments of this invention to fulfill any or all of the

above described needs in the art, and/or other needs which will become apparent to the

skilled artisan once given the following disclosure.

SUMMARY OF THE INVENTION

An object of this invention is to provide a durable coated article that can shed or

repel water (e.g. automotive windshield, automotive backlite, automotive side window, architectural window, bathroom shower glass, residential window, bathroom shower

door, coated ceramic article/tile, etc.).

Another object of this invention is to provide a hydrophobic coating system

including one or more diamond-like carbon (DLC) inclusive layers.

Another object of this invention is to provide a hydrophobic coating system

including each of DLC and FAS, the DLC being provided for durability purposes and the

FAS for increasing the contact angle of the coating system.

Yet another object of this invention, in embodiments where a hydrophobic coating

system includes multiple DLC inclusive layers and at least one FAS layer, is to form (e.g.,

via ion beam deposition techniques) a first underlying DLC inclusive layer using a first

precursor or feedstock gas and a second DLC inclusive layer over the first underlying

DLC inclusive layer using a second precursor or feedstock gas. The FAS inclusive layer

may then be applied over the DLC layers in any suitable manner. In certain

embodiments, the first underlying DLC inclusive layer may function as an anchoring

and/or barrier layer while the second or overlying DLC inclusive layer may be more

scratch resistant (i.e., harder) and/or more dense so as to improve the coated article's

durability and/or scratch resistance.

Another object of this invention is to provide a coated substrate, wherein a coating

system includes sp³ carbon-carbon bonds and FAS, and has a wettability W with regard to

water of less than or equal to about 23 mN/m, more preferably less than or equal to about 21 mN/m, even more preferably less than or equal to about 20 mN/m, and in most

preferred embodiments less than or equal to about 19 mN/meter. This can also be

explained or measured in Joules per unit area (mJ/m²)

Another object of this invention is to provide a coated substrate, wherein a coating

system includes sp³ carbon-carbon bonds and FAS, the coating system having a surface

energy γ_c (on the surface of the coated article) of less than or equal to about 20.2 mN/m,

more preferably less than or equal to about 19.5 mN/m, and most preferably less than or

equal to about 18 mN/m.

Another object of this invention is to provide a coated substrate, wherein a DLC

and FAS inclusive coating system has an initial (i.e. prior to being exposed to

environmental tests, rubbing tests, acid tests, UV tests, or the like) water contact angle θ

of at least about 80 degrees, more preferably of at least about 100 degrees, even more

preferably of at least about 110 degrees, and most preferably of at least about 125

degrees.

Another object of this invention is to provide a coated glass article wherein a DLC

and FAS inclusive coating system protects the glass from acids such as HF, nitric, and

sodium hydroxide.

Another object of this invention is to provide a coating system for a substrate that

is abrasion resistant. Another object of this invention is to manufacture a coated article having

hydrophobic qualities wherein the temperature of an underlying glass substrate may be

less than about 200° C, preferably less than about 150° C, most preferably less than

about 80° C, during the deposition of a DLC and FAS inclusive coating system. This

reduces graphitization during the deposition process, as well as reduces detempering

and/or damage to low-E and/or IR-reflective coatings already on the substrate in certain

embodiments.

Yet another object of this invention is to fulfill any and/or all of the aforesaid

objects and/or needs.

According to certain exemplary embodiments, this invention fulfills any and/or all of the above described needs and/or objects by providing a coated article comprising:

a substrate;

a hydrophobic coating system provided on said substrate, said hydrophobic coating

system including at least one diamond-like carbon (DLC) inclusive layer and at least one

fluoro-alkyl silane (FAS) compound inclusive layer; and

wherein said hydrophobic coating system has an initial contact angle θ of at least

about 80 degrees, and an average hardness of at least about 10 GPa.

This invention further fulfills any and/or all of the above described objects and/or

needs by providing a method of making a coated article, the method comprising the steps

of: providing a substrate;

depositing a first DLC inclusive layer on the substrate using a first gas including

silicon (Si);

depositing a second DLC inclusive layer on the substrate over the first DLC

inclusive layer using a second gas different than the first gas; and

applying a FAS inclusive layer over said second DLC inclusive layer in a manner

such that the resulting article has an initial contact angle θ of at least about 80 degrees.

This invention will now be described with respect to certain embodiments thereof,

along with reference to the accompanying illustrations.

IN THE DRAWINGS

Figure 1 is a side cross sectional view of a coated article according to an

embodiment of this invention, wherein a substrate is provided with a DLC and FAS

inclusive coating system thereon having hydrophobic qualities.

Figure 2 is a side cross sectional view of a coated article according to another

embodiment of this invention, wherein the DLC and FAS inclusive coating or coating

system of Figure 1 is provided over an intermediate layer(s).

Figure 3 is a side cross sectional view of a coated article including a DLC and FAS inclusive hydrophobic coating system according to another embodiment of this invention.

Figure 4(a) is a side cross sectional partially schematic view illustrating a low

contact angle θ of a water drop on a glass substrate.

Figure 4(b) is a side cross sectional partially schematic view illustrating the coated

article of any of the Figs. 1-3 embodiments of this invention and the contact angle θ of a

water drop thereon.

Figure 5 is a perspective view of a linear ion beam source which may be used in

any embodiment of this invention for depositing DLC inclusive layer(s).

Figure 6 is a cross sectional view of the linear ion beam source of Figure 5.

Figure 7 is a diagram illustrating tilt angle as discussed herein in accordance with

certain embodiments of this invention.

Figure 8 is a chart illustrating the atomic amounts of carbon, oxygen, and silicon

(relative only to one another) at different thicknesses of a sample coating system in

accordance with the Fig. 1 embodiment of this invention, but without the overlying FAS

inclusive layer.

Figure 9 is a chart illustrating the atomic amounts of carbon, oxygen, and silicon

(relative only to one another) at different thicknesses of the FAS portion of a sample

coating system in accordance with the Fig. 1 embodiment of this invention; so Figs. 8-9

can be used together to illustrate a complete coating system including both DLC and FAS inclusive layers of the Fig. 1 embodiment.

Figure 10 is a thickness vs. atomic concentration graph illustrating the different

amounts of the materials of Fig. 9 as a function of depth into the coating system of the

FAS of Fig. 9.

DETAILED DESCRIPTION OF

CERTAIN EMBODIMENTS OF THIS INVENTION

Referring now more particularly to the accompanying drawings in which like

reference numerals indicate like elements throughout the accompanying views.

Figure 1 is a side cross sectional view of a coated article according to an

embodiment of this invention, wherein a diamond-like carbon (DLC) and fluoro-alkyl

silane (FAS) inclusive coating system 5 including at least three layers 2, 3 and 6 is

provided on substrate 1. Substrate 1 may be of glass, plastic, ceramic, or the like. In

certain embodiments, each of layers 2 and 3 of the coating system 5 includes at least some

amount of highly tetrahedral amorphous carbon (ta-C). Highly tetrahedral amorphous

carbon (ta-C) forms sp³ carbon-carbon bonds, and is a special form of diamond-like

carbon (DLC). FAS inclusive layer 6 is then applied over layers 2, 3. Coating system 5

functions in a hydrophobic manner (i.e., it is characterized by high water contact angles θ

and/or low surface energies as described below), and optionally may be characterized by

low tilt angle(s) β in certain embodiments. In general, the DLC inclusive layer(s) 2

and/or 3 provide durability and/or hydrophobicity, while FAS inclusive layer 6 functions to even further increase the contact angle θ of the coating system 5.

It is surmised that the surface of DLC inclusive layer 3 includes highly reactive

dangling bonds immediately after its formation/deposition, and that the application of

FAS inclusive layer 6 onto the surface of layer 3 shortly after layer 3's formation enables

tight binding and/or anchoring of FAS inclusive layer 6 to the surface of layer 3. This

results in increased contact angle θ (improved hydrophobicity) and a durable coating

system 5. In certain embodiments of this invention, it has been found that FAS inclusive

layer 6 bonds more completely to DLC inclusive layer 3 when FAS layer 6 is applied on

the upper surface of layer 3 within one hour after layer 3 is formed, more preferably

within thirty minutes after layer 3 is formed, and most preferably within twenty minutes

after layer 3 is formed. Thus, a more durable coating system results when FAS inclusive

layer 6 is applied on DLC inclusive layer 3 shortly after layer 3 is formed.

Overlying layer 6 may be substantially all FAS, or only partially FAS in different

embodiments of this invention. Layer 6 preferably includes at least one compound having

an FAS group. Generally speaking, FAS compounds generally comprise silicon atoms

bonded to four chemical groups. One or more of these groups contains fluorine and

carbon atoms, and the remaining group(s) attached to the silicon atoms are typically alkyl

(hydrocarbon), alkoxy (hydrocarbon attached to oxygen), or halide (e.g., chlorine)

group(s). Exemplary types of FAS for use in layer 6 include CF₃(CH₂)₂Si(OCH₃)₃ [i.e., 3,

3, 3 trifluoroρroρyl)trimethoxysilane]; CF₃(CF₂)₅(CH₂)₂Si(OCH₂CH₃)₃ [i.e., tridecafluoro-1, 1, 2, 2-tetrahydrooctyl-l-triethoxysilane]; CF (CH₂)₂SiCl₃;

CF₃(CF₂)₅(CH₂)₂SiCl₃; CF₃(CF₂)₇(CH₂)₂Si(OCH₃)₃; CF₃(CF₂)₅(CH₂)₂Si(OCH₃)₃;

CF₃(CF₂)₇(CH₂)₂SiCl₃; CF₃(CF₂)₇(CH₂)₂SiCH₃Cl₂; and/or

CF₃(CF₂)₇(CH₂)₂SiCH₃(OCH₃)₂. These FAS material may be used either alone or in any

suitable combination for layer 6. At least partial hydrolysate (hydrolysed) versions of any

of these compounds may also be used. Moreover, it is noted that this list of exemplary

FAS materials is not intended to be limiting, as other FAS type materials may also be

used in layer 6. While FAS inclusive layer 6 is applied over layer 3 by physical rubbing

(or buffing) in certain preferred embodiments of this invention, layer 6 could instead be

applied in any other suitable manner in other embodiments of this invention.

According to certain embodiments of this invention, while layers 2 and 3 each

include DLC, the two layers are preferably deposited using different precursor or

feedstock gases so that the two layers have different characteristics (e.g., different

hardnesses and/or densities). In an exemplary embodiment, underlying or anchor DLC

inclusive layer 2 is deposited using an ion beam deposition technique utilizing a TMS

(tetramethylsilane) inclusive precursor or feedstock gas; while overlying DLC inclusive

layer 3 is deposited using an ion beam deposition technique utilizing a C₂H₂ (acetylene)

inclusive precursor or feedstock gas. It is believed that the underlying layer 2 (a silicon

doped DLC alloy) deposited using TMS functions as a barrier layer to prevent certain

impurities from getting into or out of the substrate. Moreover, when TMS is used in the

deposition process of underlying anchor layer 2, the Si (silicon) in layer 2 helps to enable

overlying DLC inclusive layer 3 to better bond and or adhere to the glass via anchor layer

2.

Surprisingly, it has also been found that the use of anchor layer 2 (e.g., deposited

via TMS gas) provides a more continuous/contiguous coating on a glass surface at very

thin thicknesses as compared to a DLC inclusive layer deposited using C₂H₂ (acetylene)

gas directly on glass. As a result, anchor layer 2 can be deposited first directly on the

glass at a relatively thin thickness, and the overlying layer 3 need not be as thick as

would otherwise be required. In general, the thinner the layer 3, the higher the

transmission of the overall coating system. Moreover, the provision of anchor layer 2 may enable improved yields to be achieved, as the occurrence of pinholes in the coating

system is less likely.

In embodiments where DLC inclusive layer 3 is formed on the substrate using a

C₂H₂ (acetylene) inclusive precursor or feedstock gas and underlying DLC inclusive layer

2 is formed on the substrate using at least a TMS (tetramethylsilane) inclusive precursor

or feedstock gas, the layers 2 and 3 tend to intermix with one another during the

deposition process. Thus, there may not be a clear line delineating or separating the two

layers 2 and 3 in the final product due to this intermixing (i.e., ion mixing) of the material

from the two layers. However, for purposes of simplicity, the two layers 2 and 3 are

referred to and illustrated herein as separate layers due to the different deposition

processes (e.g., gases and/or energies) used in their respective formations.

It has been found that the outer DLC inclusive layer 3 formed using a hydrocarbon

gas, such as C₂H₂ (acetylene), inclusive precursor or feedstock tends to have a greater

hardness and density than does underlying DLC inclusive layer 2 formed using a TMS

(tetramethylsilane) inclusive precursor or feedstock gas. For example, in certain

exemplary embodiments of this invention, overlying layer 3 may have an average

hardness (measured via a nano-indentation hardness measuring technique) of from about

45-85 GPa, more preferably from about 50-70 GPa, and most preferably from about 55-

60 GPa. Meanwhile, underlying DLC inclusive layer 2 may have an average hardness of

from about 10-35 GPa, and more preferably from about 15-30 GPa. Thus, the overlying layer 3 is harder than the underlying layer 2, so as to make the end product more scratch

and/or abrasion resistant. Using a nano-indentation hardness measuring technique, the

final coating system 5 , including layers 2, 3 and 6, may have a hardness of at least about

10 GPa, more preferably from about 25-60 GPa, and even more preferably from about 30-

45 GPa, which is at a hardness value between the respective hardnesses of the two DLC

inclusive layers 2 and 3.

Thus, coating system 5 includes silicon (Si) and DLC inclusive layer 2 which

functions to improve the bonding characteristics of overlying and harder DLC inclusive

layer 3 to the substrate. While the Si in layer 2 improves the bonding of layer 3 to

substrate 1, it is preferred that less Si be provided in layer 3 than in layer 2 because the

provision of Si in a DLC inclusive layer may result in decreased scratch resistance and/or

decreased hardness. Layer 3 may or may not include Si in different embodiments of this

invention. While layer 2 allows for improved bonding to the substrate, the provision of

DLC and some sp carbon-carbon bonds therein allows this anchor layer 2 to have rather

high hardness values so as to render the resulting product more durable and thus resistant

to scratching, abrasions, and the like.

In embodiments where substrate 1 is of or includes glass (e.g., soda-lime-silica

glass), anchor or intermediate DLC inclusive layer 2 may be from about 10 to 250

angstroms (A) thick, more preferably from about 10 to 150 angstroms thick, and most

preferably from about 30-50 angstroms thick; while outer DLC inclusive layer 3 may be from about 10 to 250 angstroms thick, more preferably from about 10 to 150 angstroms

thick, and most preferably about 30-60 angstroms (A) thick. FAS inclusive layer 6 may

be from about 5-80 angstroms thick, more preferably from about 20-50 angstroms thick.

However, these thicknesses are not Hmiting and the layers may be of other appropriate

thicknesses in certain embodiments of this invention. Moreover, in embodiments where

substrate 1 is of or includes plastic, layers 2, 3 and/or 6 may be of greater thickness(es)

than those described above.

In certain embodiments, layer 3 may have an approximately uniform distribution of

sp³ carbon-carbon bonds throughout a large portion of its thickness, so that much of the

layer has approximately the same density. In such embodiments, layer 2 may include a

lesser percentage of sp carbon-carbon bonds near the interface with substrate 1, with the

percentage or ratio of sp³ carbon-carbon bonds increasing throughout the thickness of the

coating system 5 toward the outermost surface. In overlying DLC inclusive layer 3, at

least about 40% (more preferably at least about 60%, and most preferably at least about

80%) of the carbon-carbon bonds in layer 3 are of the sp³ carbon-carbon type.

It is believed that the presence of sp³ carbon-carbon bonds in layer 3 increases the

density and hardness of the coating system, thereby enabhng it to satisfactorily function in

automotive environments. Layer 3 may or may not include sp carbon-carbon bonds in

different embodiments, although formation of sp² carbon-carbon bonds is likely in both

layers 2 and 3. In order to improve the hydrophobic nature of coating system 5, atoms in addition

to carbon (C) may be provided in at least overlying layer 3 in different amounts in

different embodiments. For example, in certain embodiments of this invention layer 3

(taking the entire layer thickness, or only a thin 10 A thick layer portion thereof into

consideration) may include in addition to the carbon atoms of the sp³ carbon-carbon

bonds, by atomic percentage, from about 0-20% Si (more preferably from about 0-10%),

from about 0-20% oxygen (O) (more preferably from about 0-15%), and from about 5-

60% hydrogen (H) (more preferably from about 5-35% H). Optionally, layer 3 may

include from about 0-10% (atomic percentage) fluorine (F) (more preferably from about

0-5% F) in order to further enhance hydrophobic characteristics of the coating. In

general, the provision of H in layer 3 reduces the number of polar bonds at the coating's

surface, thereby improving the coating system's hydrophobic properties.

In certain embodiments, the outermost layer portion (e.g., 5-15 angstrom thick

outermost or exterior layer portion) of layer 3 may include additional H and/or F atoms

for the purpose of increasing the coating system's hydrophobic qualities. In such

embodiments, the deposition of additional H atoms near layer 3's surface results in a more

passive or non-polar coating proximate the surface thereof.

Two exemplary coated articles were made and tested according to the Figure 1

embodiment of this invention, as follows.

For the first coated article (sample #1), DLC inclusive layers 2 and 3 were deposited on a soda-lime-silica glass substrate 1 using a linear ion beam deposition source

(see Figs. 5-6) in the following manner. TMS feedstock gas (50 seem) was used at 1,500

Volts to deposit layer 2, while C₂H₂ feedstock gas (100 seem) was used at 3,000 Volts to

deposit layer 3 directly on top of layer 2. The scan speed for each of these was 36-50

inJminute. Each of layers 2 and 3 was less than 50 angstroms thick (likely from about

20-50 angstroms thick). Sample #2 was made in the same manner as sample #1, except

that 750 Volts were used in depositing layer 2 (the same 3,000 Volts were used for layer

3). Chart 1 below lists the measured characteristics of the substrates 1 coated with layers

2 and 3, prior to deposition of FAS layer 6, for sample #s 1 and 2 of the Fig. 1

embodiment.

CHART 1

Initial Contact Angle θ Angle θ (a), 25 Taber Cycles @ 300 @ 1.000

#1 95° 104° 103° 97°

#2 95° 104° N/A 96°

As can be seen in Chart 1 above, each of these coated articles (substrate with DLC

inclusive layers 2 and 3 thereon, but no FAS layer) had an initial contact angle θ of about

95 degrees. After being subjected to 25 cycles of a Taber abrasion test, each had a

contact angle of about 104 degrees, and after being subject to 1,000 cycles of the Taber

abrasion test the articles had contact angles of 97 and 96 degrees, respectively. An FAS layer 6 was then deposited on top of a layer 3 as shown in the Figure 1

embodiment of this invention. Layer 6 was apphed by physically rubbing layer 6 onto the

exterior surface of layer 3. The measurements from this coated article (i.e., sample #3

including each of layers 2, 3 and 6 on soda-lime-silica glass substrate 1) are set forth

below in Chart 2.

CHART 2

Initial Contact Angle θ Angle θ (a), 25 Taber Cycles @ 300 @ 1.000

#3 109° 106° 100° 95°

As can be seen by comparing the results in Chart 2 (with FAS layer 6) to the

results of Chart 1 (without FAS layer 6), the provision of FAS layer 6 improved at least

the initial contact angle of the resulting coated article. Charts 1 and 2 show that the

addition of FAS layer 6 resulted in the initial contact angle improving from about 95

degrees to about 109 degrees. Thus, hydrophobic properties of the article were improved

with the addition of FAS inclusive layer 6.

Figure 2 is a side cross sectional view of a coated article according to another

embodiment of this invention, including substrate 1 (e.g. glass), hydrophobic DLC

inclusive coating system 5 including layers 2, 3, and 6 as described above with regard to

the Fig. 1 embodiment, and intermediate layer(s) 4 provided between layer 2 and substrate

1. Intermediate layer 4 may be of or include, for example, any of silicon nitride, silicon oxide, an infrared (IR) reflecting layer or layer system, an ultraviolet (UV) reflecting layer

of layer system, another DLC inclusive layer(s), or any other type of desired layer(s). In

this embodiment, it is noted that coating system 5 is still "on" substrate 1. The term "on"

herein means that substrate 1 supports DLC coating system 5, regardless of whether or

not other layer(s) (e.g. 4) are provided therebetween (this also applies to the term "over"

herein). Thus, hydrophobic coating system 5 may be provided directly on substrate 1 as

shown in Fig. 1, or may be provided on substrate 1 with another coating system or layer 4

therebetween as shown in Fig. 2.

Exemplar coatings/layers that may be used as low-E or other coating(s)/layer(s) 4

are shown and or described in any of U.S. Patent Nos. 5,837,108, 5,800,933, 5,770,321,

5,557,462, 5,514,476, 5,425,861, 5,344,718, 5,376,455, 5,298,048, 5,242,560, 5,229,194,

5,188,887 and 4,960,645, which are all hereby incorporated herein by reference.

Figure 3 illustrates another embodiment of this invention that is the same as the

Figure 1 embodiment, except that layer 2 is not provided. Thus, a single DLC inclusive

layer 3 is provided under FAS inclusive layer 6 in the Figure 3 embodiment. It has been

found that DLC inclusive layer 2 need not be provided in all embodiments of this

invention (i.e., DLC inclusive layer 2 is optional). In still further embodiments, one or

more intermediate layer(s) 4 may be provided between layer 3 and substrate 1 in the

Fi 'geu^l re 3 embodiment.

Referring to the different embodiments of Figs. 1-3, coating system 5 (or the coating system of layers 3 and 6 in the Fig. 3 embodiment) is at least about 75%

transparent to or transmissive of visible light rays, preferably at least about 85%, and most

preferably at least about 95%.

When substrate 1 is of glass, it may be from about 1.0 to 5.0 mm thick, preferably

from about 2.3 to 4.8 mm thick, and most preferably from about 3.7 to 4.8 mm thick. In

certain embodiments, another advantage of coating system 5 is that the ta-C (e.g., in

layers 2 and/or 3) therein may reduce the amount of soda (e.g., from a soda-lime-silica

glass substrate 1) that can reach the surface of the coated article and cause

stains/corrosion. In such embodiments, substrate 1 may be soda-lime-silica glass and

include, on a weight basis, from about 60-80% Si0₂, from about 10-20% Na₂0, from

about 0-16% CaO, from about 0-10% K₂0, from about 0-10% MgO, and from about 0-

5% A1₂0₃. Iron and/or other additives may also be provided in the glass composition of

the substrate 1. In certain other embodiments, substrate 1 may be soda lime silica glass

including, on a weight basis, from about 66-75% Si0₂, from about 10-20% Na₂0, from

about 5-15% CaO, from about 0-5% MgO, from about 0-5% A1₂0₃, and from about 0-5%

K₂0. Most preferably, substrate 1 is soda lime silica glass including, by weight, from

about 70-74% Si0₂, from about 12-16% Na₂0, from about 7-12% CaO, from about 3.5 to

4.5% MgO, from about 0 to 2.0% A1₂0₃, from about 0-5% K₂0, and from about 0.08 to

0.15% iron oxide. Soda lime silica glass according to any of the above embodiments may

have a density of from about 150 to 160 pounds per cubic foot (preferably about 156), an

average short term bending strength of from about 6,500 to 7,500 psi (preferably about

7,000 psi), a specific heat (0-100 degrees C) of about 0.20 Btu/lbF, a softening point of

from about 1330 to 1345 degrees F, a thermal conductivity of from about 0.52 to 0.57 Btu/hrftF, and a coefficient of linear expansion (room temperature to 350 degrees C) of

from about 4.7 to 5.0 x 10^" degrees F. Also, soda lime silica float glass available from

Guardian Industries Corp., Auburn Hills, Michigan, may be used as substrate 1. Any

such aforesaid glass substrate 1 may be, for example, green, blue or grey in color when

appropriate colorant(s) are provided in the glass in certain embodiments.

In certain other embodiments of this invention, substrate 1 may be of borosilicate

glass, or of substantially transparent plastic, or alternatively of ceramic. In certain

borosilicate embodiments, the substrate 1 may include from about 75-85% Si0₂, from

about 0-5% Na₂0, from about 0 to 4% A1₂0₃, from about 0-5% K₂0, from about 8-15%

B₂0₃, and from about 0-5% Li₂0.

In still further embodiments, an automotive window (e.g. windshield or side

window) including any of the above glass substrates laminated to a plastic substrate may

combine to make up substrate 1, with the coating system(s) of any of the Figs. 1-3

embodiments provided on the outside surface of such a window. In other embodiments,

substrate 1 may include first and second glass sheets of any of the above mentioned glass

materials laminated to one another, for use in window (e.g. automotive windshield,

residential window, commercial architectural window, automotive side window, vacuum

IG window, automotive backlight or back window, etc.) and other similar environments.

When substrate 1 of any of the aforesaid materials is coated with at least a DLC

and FAS inclusive coating system according to any of the Figs. 1-3 embodiments, the resulting coated article has the following characteristics in certain embodiments: visible

transmittance (111. A) greater than about 60% (preferably greater than about 70%, and

most preferably greater than about 80%), UV (ultraviolet) transmittance less than about

38%, total solar transmittance less than about 45%, and IR (infrared) transmittance less

than about 35% (preferably less than about 25%, and most preferably less than about

21 %). Exemplary visible, "total solar", UV, and IR transmittance measuring techniques

are set forth in Pat. No. 5,800,933, incorporated herein by reference.

Hydrophobic performance of the coating system of any of the Figs. 1-3

embodiments is a function of contact angle θ, surface energy γ, tilt angle β, and/or

wettability or adhesion energy W.

The surface energy γ of a coating system may be calculated by measuring its

contact angle θ (contact angle θ is illustrated in Figs. 4(a) and 4(b)). Fig. 4(a) shows the

contact angle of a drop on a substrate absent this invention, while Fig. 4(b) shows the

contact angle of a drop on a substrate having a coating system thereon according to this

invention. A sessile drop 31 of a liquid such as water is placed on the coating as shown

in Fig. 4(b). A contact angle θ between the drop 31 and underlying coating system 5

appears, defining an angle depending upon the interface tension between the three phases

in the point of contact. Generally, the surface energy γ_c of a coating system can be

determined by the addition of a polar and a dispersive component, as follows: γ_c = γcp +

J_CD, where γ_Cp is the coating's polar component and γ_CD the coating's dispersive component. The polar component of the surface energy represents the interactions of the

surface which is mainly based on dipoles, while the dispersive component represents, for

example, van der Waals forces, based upon electronic interactions. Generally speaking,

the lower the surface energy γ of coating system 5, the more hydrophobic the coating

and the higher the contact angle θ.

Adhesion energy (or wettability) W can be understood as an interaction between

polar with polar, and dispersive with dispersive forces, between the coating system and a

liquid thereon such as water. γ^p is the product of the polar aspects of liquid tension and

coating/substrate tension; while γ^D is the product of the dispersive forces of liquid tension

and coating/substrate tension. In other words, γ^P = γu> * γcp; and γ^D = ji , * γ_CD; where

Y _P is the polar aspect of the liquid (e.g. water), γ_Cp is the polar aspect of coating system

(e.g., coating system 5); y^ is the dispersive aspect of liquid (e.g. water), and γ_CD is the

dispersive aspect of the coating system. It is noted that adhesion energy (or effective

interactive energy) W, using the extended Fowkes equation, may be determined by:

W = [γ_Lp * YC_P]^{1 2 +} [Ϊ_LD * YC_D]^{1/2 =} Yi (1+cosθ), where y_{ is liquid tension and θ is

the contact angle. W of two materials is a measure of wettability indicative of how

hydrophobic the coating system is.

When analyzing the degree of hydrophobicity of outermost layer/portion of the

coating system 5 with regard to water, it is noted that for water Y_LP is 51 mN/m and Y_LD is

22 mN/m. In certain embodiments of this invention, the polar aspect γ_Cp of surface energy of layers 3 and 6 is from about 0 to 0.2 (more preferably variable or tunable

between 0 and 0.1) and the dispersive aspect γ_CD of the surface energy of layers 3 and 6 is

from about 16-22 mN/m (more preferably from about 16-20 mN/m). Using the above-

listed numbers, according to certain embodiments of this invention, the surface energy γ_c

of layer 6 (or 3 in certain embodiments) (and thus coating system 5) is less than or equal

to about 20.2 mN/m, more preferably less than or equal to about 19.5 mN/m, and most

preferably less than or equal to about 18.0 mN/m; and the adhesion energy W between

water and the coating system is less than about 25 mN/m, more preferably less than about

23 mN/m, even more preferably less than about 20 mN/m, and most preferably less than

about 19 mN/m. These low values of adhesion energy W and the coating system's surface

energy y_c, and the high initial contact angles θ achievable, illustrate the improved

hydrophobic nature of the coating systems 5 according to different embodiments of this

invention. While layers 3 and 6 functions to provide much of the hydrophobic nature of

the coating system 5, optional underlying DLC inclusive layer 2 improves the bonding

characteristics of the coating system 5 to the substrate 1 (e.g., glass substrate) and yet still

provides adequate hardness characteristics regarding the coating system 5 as a whole.

The initial contact angle θ of a conventional glass substrate 1 with sessile water

drop 31 thereon is typically from about 22-24 degrees, although it may dip as low as 17 or

so degrees in some circumstances, as illustrated in Figure 4(a). Thus, conventional glass

substrates are not particularly hydrophobic in nature. The provision of coating system 5

on substrate 1 causes the contact angle θ to increase to the angles discussed herein, as

shown in Fig. 4(b) for example, thereby improving the hydrophobic nature of the article.

As discussed in Table 1 of 09/303,548, the contact angle θ of a ta-C DLC layer is

typically less than 50 degrees. However, the makeup of DLC-inclusive coating system 5

described herein enables the initial contact angle θ of the system relative to a water drop

(i.e. sessile drop 31 of water) to be increased in certain embodiments to at least about 80

degrees, more preferably to at least about 100 degrees, even more preferably at least about

110 degrees, and most preferably at least about 125 degrees, thereby improving the

hydrophobic characteristics of the DLC-inclusive coating system. An "initial" contact

angle θ means prior to exposure to environmental conditions such as sun, rain, abrasions,

humidity, etc.

Figures 5-6 illustrate an exemplary linear or direct ion beam source 25 which may

be used to deposit layers 2 and 3 of coating system 5, clean a substrate, or surface plasma

treat a DLC inclusive coating with H and/or F according to different embodiments of this

invention. Ion beam source 25 includes gas/power inlet 26, anode 27, grounded cathode

magnet portion 28, magnet poles 29, and insulators 30. A 3kV DC power supply may be used for source 25 in some embodiments. Linear source ion deposition allows for

substantially uniform deposition of layers 2 and 3 as to thickness and stoichiometry. As

mentioned above, FAS inclusive layer 6 is preferably not applied using ion beam

technology (rubbing/buffing is a preferred deposition technique for layer 6), although it

may be formed in such a manner in certain embodiments of this invention.

Ion beam source 25 is based upon a known gridless ion source design. The linear

source is composed of a linear shell (which is the cathode and grounded) inside of which

lies a concentric anode (which is at a positive potential). This geometry of cathode-anode

and magnetic field 33 gives rise to a close drift condition. The magnetic field

configuration further gives rise to an anode layer that allows the linear ion beam source to

work absent any electron emitter. The anode layer ion source can also work in a reactive

mode (e.g. with oxygen and nitrogen). The source includes a metal housing with a slit in

a shape of a race track as shown in Figures 5-6. The hollow housing is at ground

potential. The anode electrode is situated within the cathode body (though electrically

insulated) and is positioned just below the slit. The anode can be connected to a positive

potential as high was 3,000 or more volts (V). Both electrodes may be water cooled in

certain embodiments. Feedstock/precursor gases, described herein, are fed through the

cavity between the anode and cathode. The gas(es) used determines the make-up of the

resulting layer deposited on an adjacent substrate 1.

The linear ion source also contains a labyrinth system that distributes the precursor gas (e.g., TMS (i.e., (CH₃)₄Si or tetramethylsilane); acetylene (i.e., C₂H₂); 3MS (i.e.,

trimethyldisilane); DMS (i.e., dichloro-dimethylsilane); HMDSO (i.e.,

hexamethyldisiloxane); TEOS (i.e., tetraethoxysilane), etc.) fairly evenly along its length

and which allows it to supersonically expand between the anode-cathode space internally.

The electrical energy then cracks the gas to produce a plasma within the source. The

ions are expelled out at energies in the order of eVc-a/2 when the voltage is Vc-a. The

ion beam emanating from the slit is approximately uniform in the longitudinal direction

and has a Gaussian profile in the transverse direction. Exemplary ions 34 are shown in

Figure 6. A source as long as one meter may be made, although sources of different

lengths are anticipated in different embodiments of this invention. Finally, electron layer

35 is shown in Figure 6 completes the circuit thereby enabling the ion beam source to

function properly.

In alternative embodiments of this invention, an ion beam source device or

apparatus as described and shown in Figs. 1-3 of U.S. Patent No. 6,002,208 (hereby

incorporated herein by reference in its entirety) may be used to deposit/form DLC

inclusive layers 2 and 3 on substrate 1 in accordance with either the Fig. 1, Fig. 2, or Fig.

3 embodiment of this invention. One or multiple such ion beam source devices may be

used.

In certain embodiments, the same ion beam source 25 may be used to deposit both

of layers 2 and 3; one after the other. In other embodiments of this invention two separate ion beam sources may be provided, a first for depositing layer 2 on substrate 1 and the

second for depositing layer 3 over layer 2. In certain embodiments, another ion beam

source may be provided for initially cleaning the surface of substrate 1 prior to deposition

of layers 2, 3. After layers 2 and 3 are deposited, FAS inclusive layer 6 is preferably

applied thereon.

Referring to Fig. 7, tilt angle β characteristics associated with certain embodiments

of this invention will be explained. In a hydrophobic coating, it is often desirable in

certain embodiments to have a high contact angle θ (see Fig. 4(b)) in combination with a

low tilt angle β. As shown in Fig. 7, tilt angle β is the angle relative to the horizontal 43

that the coated article must be tilted before a 30 μL (volume) drop 41 (e.g., of water)

thereon begins to flow down the slant at room temperature without significant trail. A

low tilt angle means that water and/or other liquids may be easily removed from the

coated article upon tilting the same or even in high wind conditions. In certain

embodiments of this invention, coated articles herein (with layers 2, 3 and 6) have an

initial tilt angle β of no greater than about 30 degrees, more preferably no greater than

about 20 degrees, and even more preferably no greater than about 10 degrees. In certain

embodiments, the tilt angle does not significantly increase over time upon exposure to the

environment and the like, while in other embodiments it may increase to some degree

over time.

Referring to Figures 1 and 5-6, an exemplary method of depositing a coating system 5 on substrate 1 will now be described. This method is for purposes of example

only, and is not intended to be limiting.

Prior to coating system 5 being formed on glass substrate 1, the top surface of

substrate 1 may be cleaned by way of a first linear or direct ion beam source. For

example, a glow discharge in argon (Ar) gas or mixtures of Ar/0₂ (alternatively CF

plasma) may be used to remove any impurities on the substrate surface. Such interactions

are physio-chemical in nature. This cleaning creates free radicals on the substrate surface

that subsequently can be reacted with other monomers yielding substrate surfaces with

specialized properties. The power used may be from about 100-300 Watts. Substrate 1

may also be cleaned by, for example, sputter cleaning the substrate prior to actual

deposition of coating system 5; using oxygen and/or carbon atoms at an ion energy of

from about 800 to 1200 eV, most preferably about 1,000 eV.

After cleaning, the deposition process begins using a linear ion beam deposition

technique via second ion beam source as shown in Figs. 5-6, or in Figs. 1-3 of the '208

patent; with a conveyor having moved the cleaned substrate 1 from first source to a

position under the second source. The second ion beam source functions to deposit a

DLC inclusive layer 2 on substrate 1, with at least TMS being used as the precursor or

feedstock gas fed through the source. Because of the Si in the TMS gas used in the

source, the resulting layer 2 formed on substrate includes at least Si as well as DLC. The

Si portion of DLC inclusive layer 2 enables good bonding of layer 2 to substrate 1 (substrate 1 is glass in this example), and thus will also improve the bonding

characteristics of layer 3 to the substrate via layer 2.

After layer 2 has been formed, either the same or another ion beam source is used

to deposit layer 3 over (directly on in preferred embodiments) layer 2. To deposit

overlying DLC inclusive layer 3, another gas such as at least C₂H₂ is fed through the

source so that the source expels the ions necessary to form layer 3 overlying layer 2 on

substrate 1. The C₂H₂ gas may be used alone, or in exemplary alternative embodiments

the gas may be produced by bubbling a carrier gas (e.g. C₂H₂) through a precursor

monomer (e.g. TMS or 3MS) held at about 70 degrees C (well below the flashing point).

Acetylene feedstock gas (C₂H₂) is used in certain embodiments for depositing layer 3 to

prevent or minimize/reduce polymerization (layer 2 may be polymerized in certain

embodiments) and to obtain an appropriate energy to allow the ions to penetrate the

surface on the substrate/layer 2 and subimplant therein, thereby causing layer 3 to

intermix with layer 2 in at least an interface portion between the layers. The actual gas

flow may be controlled by a mass flow controller (MFC) which may be heated to about

70 degrees C. In certain optional embodiments, oxygen (0₂) gas may be independently

flowed through an MFC. The temperature of substrate 1 may be room temperature; an

arc power of about 1000 W may be used; precursor gas flow may be about 25 seem; the

base pressure may be about 10^"6 Torr. The optimal ion energy window for the majority

of layers 2, 3 is from about 100-1,000 eV (preferably from about 100-400 eV) per carbon ion. At these energies, the carbon in the resulting layers 2, 3 emulates diamond, and sp³

C-C bonds form. However, compressive stresses can develop in ta-C when being

deposited at 100-150 eV. Such stress can reach as high as 10 GPa and can potentially

cause delamination from many substrates. It has been found that these stresses can be

controlled and decreased by using an ion energy during the deposition process in a range

of from about 200-1,000 eV.

As stated above, layers 2 and 3 intermix with one another at the interface between

the two layers, thereby improving the bonding between the layers. At particle energies

(carbon energies) of several hundred eV, a considerable material transport can take place

over several atomic distances. This is caused by the penetration of fast ions and neutrals

as well as by the recoil displacement of struck atoms. At sufficiently high particle

energies and impact rates, there is an enhanced diffusion of the thermally agitated atoms

near the film surface that occurs via the continuously produced vacancies. In the

formation of ta-C:H, these effects can help improve film adhesion by broadening the

interface (i.e., making it thicker, or making an interfacial layer between the two layers 2

and 3 (or between layer 2 and glass 1) due to atom mixing). After layer 2 is deposited,

the carbon from layer 3 implants into layer 2 (i.e., subimplantation) so as to make the

bond better of layer 3 to the substrate. Thus, layers 2 and 3 are contiguous due to this

intermixing, and this "smearing" between the layers enhances the adhesion of layer 3 to

both layer 2 and thus the substrate 1. High stress is undesirable in the thin interfacing portion of layer 2 that directly

contacts the surface of a glass substrate 1 in the Figure 1 embodiment. Thus, for

example, the first 1-40% thickness (preferably the first 1-20% and most preferably the

first 5-10% thickness) of layer 2 may optionally be deposited on substrate 1 using high

anti-stress energy levels of from about 200-1,000 eV, preferably from about 400-500 eV.

Then, after this initial interfacing layer portion of layer 2 has been grown, the ion energy

in the ion deposition process may be decreased (either quickly or gradually while

deposition continues) to about 100-200 eV, preferably from about 100-150 eV, to grow

the remainder of layer(s) 2 and/or layer 3. Thus, in certain embodiments, because of the

adjustment in ion energy and/or gases during the deposition process, DLC inclusive layers

2, 3 may optionally have different densities and different percentages of sp³ C-C bonds at

different layer portions thereof (the lower the ion energy, the more sp C-C bonds and the

higher the density).

While direct ion beam deposition techniques are preferred in certain embodiments,

other methods of deposition may also be used in different embodiments. For example,

filtered cathodic vacuum arc ion beam techniques may be used to deposit layers 2, 3.

Also, in certain embodiments, CH₄ may be used as a feedstock gas during the deposition

process instead of or in combination with the aforesaid C₂H₂ gas.

Optionally, the outer surface of layer 3 may be treated using a plasma treatment by

another source or grafting procedure (prior to formation of FAS layer 6). This technique using an ion beam source may remove certain polar functional groups at the outermost

surface of layer 3, thereby altering the surface chemical reactivity (i.e. lowering surface

energy) of layer 3. In such optional embodiments, after a conveyor has moved the DLC-

coated substrate from the second source station to a position under this another source,

the plasma treatment by this source may introduce, e.g., hydrogen (H) atoms into the

outermost surface of layer 3, thereby making layer 3's surface substantially non-polar and

less dense than the rest of layer 3. These H atoms are introduced, because H₂ and/or ArH₂

feedstock gas is used by this source in certain embodiments. Thus, this source does not

deposit any significant amounts of C atoms or Si atoms; but instead treats the outermost

surface of layer 3 by adding H atoms thereto in order to improve its hydrophobic

characteristics. This plasma treatment may also function to roughen the otherwise smooth

surface. It is noted that H₂ feedstock gas is preferred in the ion beam source when it is

not desired to roughen the surface of coating system 5, while ArH₂ feedstock gas is

preferred in surface roughing embodiments. In other optional embodiments, this source

may be used to implant F ions/atoms in to the outermost surface of layer 3.

After DLC inclusive layers 2 and 3 have been formed on substrate 1, FAS

inclusive layer 6 is applied thereto as shown in Fig. 1 (e.g., by rubbing or otherwise

applying this layer 6 in any other suitable manner).

Optionally, after layer 6 has been formed on the substrate 1, the coated article may

be heated (e.g., up to about 100 degrees C in certain embodiments, or up to about 300 degrees C in other embodiments). Surprisingly, it has been found that heating the coated

article in such a manner improves the durability of FAS inclusive layer 6, and thus of the

overall coating system. It is thought that such hearing may "cure" layer 6 or otherwise

cause it to more completely bond to itself and/or layer 3.

Coating system 5 according to different embodiments of this invention may have

the following characteristics: coefficient of friction of from about 0.02 to 0.15; good

abrasion resistance; an average density of from about 2.0 to 3.0 g/cm²; permeability

barrier to gases and ions; surface roughness less than about 0.5 nm; inert reactivity to

acids, alkalis, solvents, salts and water; corrosion resistance; variable or tunable surface

tension; tunable optical bandgap of from about 2.0 to 3.7 eV; IR transmission @ 10 μm of

at least about 85%; UV transmission @ 350 nm of no greater than about 30%; tunable

refractive index @ 550 nm [n=1.6 to 2.3; k=0.0001 to 0.1], permittivity @ GHz 4.5; an

undoped electrical resistivity of at least about 10¹⁰ Ω/cm dielectric constant of about 11

@ 10 kHz and 4 @ 100 MHz; an electrical breakdown strength (V cm^"1) of about 10⁶;

thermal coefficient of expansion of about 9 x 10^"6/C; and thermal conductivity of about

O.l Wcm K.

Three examples of optional TMS-formed DLC inclusive anchor layers 2 are as

follows. Each such layer 2 was deposited on substrate 1 using tetramethylsilane (TMS)

and 0₂ gas introduced within the linear ion beam source apparatus of Figs. 5-6. All

samples were of approximately the same thickness of about 750 A. A low energy electron flood gun was used to sharpen the spectral analysis conducted by x-ray photo

electron spectroscopy (XPS) for chemical analysis. In XPS analysis of a layer 2, high

energy x-ray photons (monochromatic) impinge on the surface of the layer. Electrons

from the surface are ejected and their energy and number (count) measured. With these

measurements, one can deduce the electron binding energy. From the binding energy,

one can determine three things: elemental fingerprinting, relative quantity of elements,

and the chemical state of the elements (i.e. how they are bonding). Components used in

the XPS analysis include the monochromatic x-ray source, an electron energy analyzer,

and electron flood gun to prevent samples from charging up, and an ion source used to

clean and depth profile. Photoelectrons are collected from the entire XPS field

simultaneously, and using a combination of lenses before and after the energy analyzer

are energy filtered and brought to a channel plate. The result is parallel imaging in real

time images. Sample Nos. 1-3 of DLC inclusive layer 2 were made and analyzed using

XPS, which indicated that the samples included the following chemical elements by

atomic percentage (H was excluded from the chart below).

CHART 3

Sample No. C O Si F

1 54.6% 23.7% 20.5% 1.2%

2 45.7% 21.7% 32.7% 0% 3 59.5% 22.7% 17.8% 0%

H was excluded from the XPS analysis because of its difficulty to measure. Thus,

H atoms present in the coating Sample Nos. 1-3 of Chart 3 were not taken into

consideration for these results. For example, if Sample No. 1 in Chart 3 included 9% H

by atomic percentage, then the atomic percentages of each of the above-Usted elements C,

O, Si and F would be reduced by an amount so that all five atomic percentages totaled

100%. As can be seen, F is optional and need not be provided. Oxygen is also optional.

While TMS is described above as a primary precursor or feedstock gas utilized in

the ion beam deposition source for depositing the optional underlying DLC inclusive

layer 2, other gases may in addition or instead be used. For example, other gases such as

the following may be used either alone, or in combination with TMS, to form layer 2:

silane compounds such as TMS, diethylsilane, TEOS, dichlorodimethylsilane,

trimethyldisilane, hexamethyldisiloxane, organosilane compounds; organosilazane

compounds such as hexamethyldisilazane and tetramethyldisilazane; and/or organo-

oxysilicon compounds such as tetramethyldisiloxane, ethoxytrimethylsilane, and organo-

oxysilicon compounds. Each of these gases includes Si; and each of these gases may be

used either alone to form layer 2, or in combination with one or more of the other listed

gases. In certain embodiments, the precursor gas may also further include N, F and/or O

in optional embodiments, for layer 2 and/or layer 3.

With regard to layer 3, a hydrocarbon gas such as acetylene is preferred for forming the layer. However, other gases such as ethane, methane, butane, cyclohexane,

and/or mixtures thereof may also (or instead) be used in the ion beam source to form layer

In certain embodiments of this invention (e.g., see Figs. 1-3), coating system 5 has

a contact angle of at least about 70°, more preferably at least about 80°, and even more

preferably at least about 100° after a taber abrasion resistance test has been performed

pursuant to ANSI Z26.1. The test utilizes 1,000 rubbing cycles of coating system 5, with

a load a specified in Z26.1 on the wheel(s). Another purpose of this abrasion resistance

test is to determine whether the coated article is resistive to abrasion (e.g. whether hazing

is less than 4% afterwards). ANSI Z26.1 is hereby incorporated into this application by

reference.

Figures 8-10 illustrate the makeup of a coating system 5 including layers 2, 3 and 6

according to an embodiment of this invention. However, Figs. 8 and 9 must be looked at

together to span the entire coating system of layers 2, 3 and 6. Figure 8 shows the make-

up with regard to C, O and Si for layers 2 and 3, while Figure 9 shows the make-up with

regard to C, O and Si for layer 6, throughout the respective thicknesses of these layers.

X-ray Photoelectron Spectroscopy (XPS)/Electron Spectroscopy for Chemical Analysis

(ESCA) was used to develop these graphs from sample products. This is used to

characterize inorganic and organic solid materials. In order to perform such

measurements on sample products as was done with regard to Figs. 8-10, surfaces of the coating system were excited with Al monochromatic x-rays (1486.6 eV) and the

photoelectrons ejected from the surface were energy analyzed. Low resolution analysis,

i.e., a survey scan, can be used to identify elements (note that H, He, and F were not

included in the analysis of Figs. 8-10 even though at least H and/or F were present in the

coating system 5) and establish the illustrated concentration table in units of atomic

percentage (%). Detection limits were from about 0.1 to 0.05 atom %. High resolution

analysis of individual photoelectron signals, i.e., C Is, can be used to identify chemical

bonding and/or oxidation state. Information on the surface is obtained from a lateral

dimension as large as 1 mm diameter and from a depth of 0-10 μm. To acquire

information from slightly greater depths, angle resolved measurements can be made.

Fig. 8 illustrates the makeup with regard to C, O and Si throughout the thicknesses

of DLC inclusive layers 2 and 3 of coating system 5 of the Fig. 1 embodiment (i.e., no

FAS layer was on layers 2 and 3 when this data was measured). Cycle number 1 is at the

outer surface of layer 3, while cycle number 19 is believed to be within the underlying

glass substrate 1. Thus, it is believed that the interface between glass substrate 1 and

underlying DLC inclusive layer 2 is at about cycle number 15 where the C % begins to

significantly decrease. The "time" and "depth" columns refers to depth into layers 3, 2

from the exterior surface of layer 3 as compared to the depth into a conventional Si0₂ that

would be achieved over the same time period. Thus, the angstrom depth illustrated in

Fig. 8 is not the actual depth into layers 3, 2, but instead is how deep into a Si0₂ layer the sputtering would reach over the corresponding time. In Fig. 8, cycle number 1 may be

affected from contamination of the outer surface of layer 3 and may be disregarded in

effect. At least cycle numbers 2-6 refer or correspond to DLC inclusive layer 3 as

evidenced by the high carbon amounts (i.e., greater than 94% C in layer 3 according to

Fig. 8). Meanwhile, at least cycle numbers 9-13 refer or correspond to underlying DLC

inclusive layer 2, as evidence by the lower C amounts shown in Fig. 8. Thus, it can be

seen that layer 2 includes less C than layer 3, and is therefor less dense and less hard.

Moreover, it can be seen that layer 2 includes more Si than layer 3 (and optionally more

oxygen (O)). Cycle numbers 7-8 refer or correspond to the interface or intermixing layer

portion between layers 2 and 3; as the coating system 5 at these thickness portions

includes C and Si amounts between the amounts in respective layers 2 and 3. Thus, these

cycle numbers 7-8 illustrate the intermixing (i.e., subimplantation of atoms from layer 3

in layer 2) or smearing between layers 2, 3 discussed herein. Meanwhile, cycle numbers

14-15 refer or correspond to the interfacial layer between layer 2 and the glass substrate 1,

while cycle numbers 16-19 refer or correspond to the glass itself with its high Si0₂

content.

Figure 9 illustrates a similar make-up, but of FAS layer 6 (i.e., with regard to only

C, O and Si throughout the thickness of layer 6). The layer 6 analyzed in Figs. 9-10 was

of the CF₃(CH₂)₂Si(OCH₃)₃ type of FAS. Cycle number 1 is at the exterior surface of

layer 6 where layer 6 meets the surrounding atmosphere, while cycle number 11 is believed to be in layer 6 near where the layer 6 meets the exterior surface of DLC

inclusive layer 3. As can be seen by comparing Figures 8 and 9, the FAS inclusive layer

6 has much less carbon than does layer 3. Figure 10 is a graph illustrating the results of

Fig. 9 (absent the make-up of layers 2 and 3).

As will be appreciated by those skilled in the art, coated articles according to

different embodiments of this invention may be utilized in the context of automotive

windshields, automotive side windows, automotive backlites (i.e., rear windows),

architectural windows, residential windows, ceramic tiles, shower doors, and the like.

Once given the above disclosure, many other features, modifications, and

improvements will become apparent to the skilled artisan. Such other features,

modifications, and improvements are, therefore, considered to be a part of this invention,

the scope of which is to be determined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A coated article comprising: a substrate;

a hydrophobic coating system provided on said substrate, said hydrophobic coating

system including at least one diamond-like carbon (DLC) inclusive layer and at least one

fluoro-alkyl silane (FAS) compound inclusive layer; and

wherein said hydrophobic coating system has an initial contact angle θ of at least

about 80 degrees, and an average hardness of at least about 10 GPa.

2. The coated article of claim 1, wherein the substrate is a glass substrate

comprising, on a weight basis:

Si0₂ from about 60-80%,

Na₂0 from about 10-20%),

CaO from about 0-16%,

K₂0 from about 0-10%,

MgO from about 0-10%,

A1₂0₃ from about 0-5%; and

wherein said DLC inclusive layer includes sp³ carbon-carbon bonds.

3. The coated article of claim 1, wherein said hydrophobic coating system

includes first and second DLC inclusive layers, said first DLC inclusive layer including

silicon (Si) and being provided between said DLC inclusive second layer and said

substrate; and

wherein said second DLC inclusive layer is deposited in a manner so that at least a

portion of said second DLC inclusive layer has a greater hardness and higher density than

said first DLC inclusive layer.

4. The coated article of claim 3, wherein said hydrophobic coating system

further includes said FAS inclusive layer provided on said second DLC inclusive layer, so

that said second DLC inclusive layer is located between said first DLCinclusive layer

and said FAS inclusive layer.

5. The coated article of claim 1, wherein said initial contact angle is at least

about 100 degrees.

6. The coated article of claim 5, wherein said initial contact angle is at least

about 110 degrees.

7. The coated article of claim 6, wherein said initial contact ang ol*e is at least

about 125 de agr¹-ees

8. The coated article of claim 1, wherein said coating system has a surface

energy γ_c of less than or equal to about 20.2 mN/m.

9. The coated article of claim 1, wherein said coating system has a surface

energy γ_c of less than or equal to about 19.5 mN/m.

10. The coated article of claim 1, wherein said coating system has a surface

energy γ_c of less than or equal to about 18.0 mN/m, and wherein a refractive index "n" of

a DLC inclusive layer is from about 1.5 to 1.7.

11. The coated article of claim 1, wherein said FAS compound includes at least

one of: CF₃(CH₂)₂Si(0CH₃)₃; CF₃(CF₂)₅(CH₂)₂Si(0CH₂CH₃)₃; CF₃(CH₂)₂SiCl₃;

CF₃(CF₂)₅(CH₂)₂SiCl₃; CF₃(CF₂)₇(CH₂)₂Si(OCH₃)₃; CF₃(CF₂)5(CH2)2Si(OCH₃)₃;

CF₃(CF₂)₇(CH₂)₂SiCl₃; CF₃(CF₂)₇(CH₂)₂SiCH₃Cl₂; and CF₃(CF₂)₇(CH₂)₂SiCH₃(0CH₃)₂.

12. The coated article of claim 1, further comprising at least one intermediate

layer disposed between said coating system and said substrate, and wherein said substrate

is one of glass, plastic and ceramic.

13. The coated article of claim 1, further comprising a low-E or IR-reflective

layer system disposed between said coating system and said substrate.

14. The coated article of claim 1, wherein said FAS inclusive layer is heated

after its formation on the substrate to an extent sufficient to increase durability of said

FAS inclusive layer.

15. The coated article of claim 1, wherein said hydrophobic coating system has

an average hardness of at least about 20 GPa.

16. The coated article of claim 1, wherein said coating system comprises first

and second DLC inclusive layers, and wherein said first DLC inclusive layer is deposited

using a first gas including silicon (Si) in an ion beam source and said second DLC

inclusive layer is deposited using a second gas different than said first gas.

17. The coated article of claim 16, wherein said first DLC inclusive layer

comprises more silicon (Si) than said second DLC inclusive layer.

18. The coated article of claim 1, wherein the coated article comprises the

following characteristics:

visible transmittance (111. A): > 60%

UV transmittance: < 38%

IR transmittance: < 35%.

19. The coated article of claim 17, wherein each of said first and second DLC

inclusive layers include sp carbon-carbon bonds.

20. The coated article of claim 19, wherein at least about 50% of carbon-carbon

bonds in said second DLC inclusive layer are sp³ carbon-carbon bonds, and where said

first DLC inclusive layer is located between said substrate and said second DLC inclusive

layer.

21. A coated article comprising:

a substrate;

a coating system including diamond-like carbon (DLC) and at least one fluoro-

alkyl silane (FAS) compound; and

wherein said coating system has an initial contact angle θ with a drop of water of

at least about 80 degrees.

22. The article of claim 21, wherein said coating system has an average hardness

of at least about 10 GPa.

23. The article of claim 21, wherein said coating system includes first and second

DLC inclusive layers of different hardnesses and a first FAS. inclusive layer, wherein said

second DLC inclusive layer is harder than said first DLC inclusive layer and said second

DLC inclusive layer is located between said FAS inclusive layer and said first DLC

inclusive layer.

24. The article of claim 23, wherein said first DLC inclusive layer includes more

Si than said second DLC inclusive layer.

25. The article of claim 21, wherein said initial contact angle is at least about

100 degrees.

26. The article of claim 21, wherein said substrate comprises at least one of

glass, ceramic, and plastic; and wherein said FAS compound includes at least one of: CF₃(CH₂)₂Si(0CH₃)₃;

CF₃(CF₂)₅(CH₂)₂Si(0CH₂CH₃)₃; CF₃(CH₂)₂SiCl₃; CF₃(CF₂)₅(CH₂)₂SiCl₃;

CF₃(CF₂)₇(CH₂)₂Si(OCH₃)₃; CF₃(CF₂)₅(CH₂)₂Si(OCH₃)₃; CF₃(CF₂)₇(CH₂)₂SiCl₃;

CF₃(CF₂)₇(CH₂)₂SiCH₃Cl₂; and CF₃(CF₂)₇(CH₂)₂SiCH₃(0CH₃)₂.

27. The article of claim 21, wherein said coating system has an average

hardness of from about 20-80 GPa.

28. A method of making a coated article, the method comprising the steps of:

providing a substrate;

depositing a first DLC inclusive layer on the substrate using a first gas including

silicon (Si);

depositing a second DLC inclusive layer on the substrate over the first DLC

inclusive layer using a second gas different than the first gas; and

applying a FAS inclusive layer over said second DLC inclusive layer.

29. The method of claim 28, further comprising depositing the second DLC

inclusive layer in a manner so as to include ta-C, and applying the FAS inclusive layer in

a manner so that the resulting article has an initial contact angle θ of at least about 80

30. The method of claim 28, wherein said first gas includes a silane compound

and said second gas includes a hydrocarbon.

31. The method of claim 28, wherein said first gas comprises at least one of

tetramethylsilane, trimethyldisilane, tetraethoxysilane, hexamethyldisiloxane, and

dichlorodimethylsilane.

32. The method of claim 28, wherein the second gas comprises C₂H₂.

33. The method of claim 28, wherein the first layer is deposited in direct

contact with the substrate using at least plasma ion beam deposition, and wherein said

FAS inclusive layer is applied so as to be in direct or indirect contact with said second

DLC inclusive layer.

34. The method of claim 28, further comprising the step of depositing an

intermediate layer in a manner such that the intermediate layer is located between a) the

substrate, and b) the first and second DLC inclusive layers.

35. The method of claim 28, further comprising the step of depositing the first

and second DLC inclusive layers in a manner such that the first DLC inclusive layer

includes substantially more Si than the second DLC inclusive layer.

36. A method of making a coated article comprising the steps of:

providing a substrate; and

forming a coating system on said substrate in a manner such that the coating

system includes each of diamond-like carbon (DLC) and at least one fluoro-alkyl silane

(FAS) compound.

37. The method of claim 36, wherein the coating system includes at least one DLC

inclusive layer and at least one FAS inclusive layer.

38. The method of claim 37, wherein the FAS inclusive layer is applied on a

surface of the DLC inclusive layer within about 60 minutes after formation of the DLC

inclusive layer on the substrate.

39. The method of claim 37, further comprising the step of heating the FAS

inclusive layer after its formation on the substrate in order to increase its durability.