Heat treatable coated article with diamond-like carbon (DLC) and/or zirconium in coating

0001This invention relates to a method of making a coated article to be used in a window unit or any other suitable application such as furniture glass or picture frame glass. For example, certain embodiments of this invention relate to a method of making a window unit (e.g., vehicle window such as vehicle windshield, backlite, sunroof, or sidelite, or IG window unit, or shower door window) including a step of heat treating a glass substrate coated with at least a layer comprising zirconium nitride. In certain example embodiments, the glass substrate may be coated with only a layer of or including zirconium nitride, and the be heat treated where the zirconium nitride inclusive layer transforms into a layer comprising zirconium oxide due to the heat treatment.

0002Certain other example embodiments of this invention relate to such a coated article, heat treated or not, which may be used in window applications, or any other suitable application such as furniture glass or the like.

BACKGROUND OF THE INVENTION

0003Vehicle windows (e.g., windshields, backlites, sunroofs, and sidelites) are known in the art. For purposes of example, vehicle windshields typically include a pair of bent glass substrates laminated together via a polymer interlayer such as polyvinyl butyral (PVB). It is known that one of the two glass substrates may have a coating (e.g., low-E coating) thereon for solar control purposes such as reflecting IR and/or UV radiation, so that the vehicle interior can be more comfortable in certain weather conditions. Conventional vehicle windshields are made as follows. First and second flat glass substrates are provided, one of them optionally having a low-E coating sputtered thereon. The pair of glass substrates are washed and booked together (i.e., stacked on one another), and then while booked are heat bent together into the desired windshield shape at a high temperature(s) (e.g., 8 minutes at about 600-625 degrees C). The two bent glass substrates are then laminated together via the polymer interlayer to form the vehicle windshield.

0004Insulating glass (IG) window units are also known in the art. Conventional IG window units include at least first and second glass substrates (one of which may have a solar control coating on an interior surface thereof) that are coupled to one another via at least one seal(s) or spacer(s). The resulting space or gap between the glass substrates may or may not be filled with gas and/or evacuated to a low pressure in different instances. However, many IG units are required to be tempered. Thermal tempering of the glass substrates for such IG units typically requires heating the glass substrates to temperature(s) of at least about 600 degrees C for a sufficient period of time to enable thermal tempering.

0005Other types of coated articles also require heat treatment (HT) (e.g., tempering, heat bending, and/or heat strengthening) in certain applications. For example and without limitation, glass shower doors, glass table tops, and the like require HT in certain instances.

0006Diamond-like carbon (DLC) is sometimes known for its scratch resistant properties. For example, different types of DLC are discussed in the following <patcit id="pcit0001" dnum="US6303226B"><text>U.S. Patents: 6,303,226</text></patcit>; <patcit id="pcit0002" dnum="US6303225B"><text>6,303,225</text></patcit>; <patcit id="pcit0003" dnum="US6261693B"><text>6,261,693</text></patcit>; <patcit id="pcit0004" dnum="US6338901B"><text>6,338,901</text></patcit>; <patcit id="pcit0005" dnum="US6312808B"><text>6,312,808</text></patcit>; <patcit id="pcit0006" dnum="US6280834B"><text>6,280,834</text></patcit>; <patcit id="pcit0007" dnum="US6284377B"><text>6,284,377</text></patcit>; <patcit id="pcit0008" dnum="US6335086B"><text>6,335,086</text></patcit>; <patcit id="pcit0009" dnum="US5858477A"><text>5,858,477</text></patcit>; <patcit id="pcit0010" dnum="US5635245A"><text>5,635,245</text></patcit>; <patcit id="pcit0011" dnum="US5888593A"><text>5,888,593</text></patcit>; <patcit id="pcit0012" dnum="US5135808A"><text>5,135,808</text></patcit>; <patcit id="pcit0013" dnum="US5900342A"><text>5,900,342</text></patcit>; and <patcit id="pcit0014" dnum="US5470661A"><text>5,470,661</text></patcit>, all of which are hereby incorporated herein by reference.

0007Document <patcit id="pcit0015" dnum="WO2005021456A1"><text>WO 2005/021456 A1</text></patcit> describes a method for making a heat treated coated article, wherein a layer comprising diamond like carbon (DLC) is provided next to a layer of zirconium nitride on a substrate. During a heat treatment step the DLC layer burns at least partially off, thereby creating enough energy to transform the zirconium nitride to zirconium oxide after heat treatment.

0008Document <patcit id="pcit0016" dnum="WO2005021454A1"><text>WO 2005/021454 A1</text></patcit> describes a method for making a heat treated coated article, wherein a layer comprising diamond like carbon (DLC) is provided on a substrate and a protective layer of zirconium nitride is provided over the DLC layer. The layer of zirconium nitride serves to protects the DLC layer during a heat treatment step.

0009It would sometimes be desirable to provide a window unit or other glass article with a protective coating including DLC in order to protect it from scratches and the like. Unfortunately, DLC tends to oxidize and burn off at temperatures of from approximately 380 to 400 degrees C or higher, as the heat treatment is typically conducted in an atmosphere including oxygen. Thus, it will be appreciated that DLC as a protective overcoat cannot withstand heat treatments (HT) at the extremely high temperatures described above which are often required in the manufacture of vehicle windows, IG window units, glass table tops, and/or the like. Accordingly, DLC cannot be used alone as a coating to be heat treated, because it will oxidize during the heat treatment and substantially disappear as a result of the same (i.e., it will burn off).

0010Certain other types of scratch resistant materials also are not capable of withstanding heat treatment sufficient for tempering, heat strengthening and/or bending of an underlying glass substrate.

0011Accordingly, those skilled in the art will appreciate that a need in the art exists for a method of making a scratch resistant coated article that is capable of being heat treated (HT) so that after heat treatment the coated article is still scratch resistant. A need for corresponding coated articles, both heat treated and pre-HT, also exists.

BRIEF SUMMARY OF EXAMPLES OF INVENTION

0012In certain example embodiments of this invention, there is provided a method of making a coated article (e.g., window unit such as for a vehicle, building, or the like) that is capable of being heat treated so that after being heat treated (HT) the coated article is scratch resistant to an extent more than uncoated glass.

0013In certain example embodiments of this invention, prior to heat treatment a coated article includes a layer of or including zirconium nitride on a glass substrate. This may be the only layer on the glass substrate in certain example embodiments, or alternatively other layers may be present. Heat treatment (e.g., thermal tempering) of the coated article causes the zirconium nitride inclusive layer to transform either partially or entirely into a layer of or including zirconium oxide that can be used for scratch resistant purposes.

0014In certain example instances, that are not limiting, the zirconium oxide inclusive layer following heat treatment may be buffed or surface treated in order to improve scratch resistance thereof. Moreover, the zirconium nitride inclusive layer, and thus the zirconium nitride inclusive layer, may be doped with other materials such as F in certain example non-limiting instances.

0015In certain example embodiments, at least prior to heat treatment, the layer(s) comprising zirconium nitride may be doped with fluorine (F) and/or carbon (C). Surprisingly, it has been found that this tends to increase the visible transmission of the heat treated coated article.

0016The new post-HT layer comprising zirconium oxide is surprisingly scratch resistant. Thus, it can be seen that a technique has been provided which allows for a heat treatable scratch resistant product; and the coated article may also have good transmission properties. In certain example embodiments, the scratch resistance of the post-HT coated article may even be better than that of non-HT DLC.

0017In certain example embodiments, there is provided a method of making a heat treated coated article, the method comprising: providing a coating supported by a glass substrate, the coating comprising a zirconium nitride based layer; and thermally tempering the glass substrate with the zirconium nitride based layer thereon, so that the tempering causes the zirconium nitride based layer to transform into a layer comprising zirconium oxide (Zr_xO_y) where y/x is from about 1.2 to 2.5. A layer(s) comprising diamond-like carbon may optionally be provide over and/or under the layer comprising zirconium nitride in certain example embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

0018<figref idref="f0001 f0002 f0003 f0004 f0005 f0006">Figures 1-7</figref> are illustrations of reference examples for the present invention only.

0019<figref idref="f0001">FIGURE 1</figref> is a schematic diagram illustrating coated articles before and after heat treatment.

0020<figref idref="f0002">FIGURE 2</figref> is a schematic diagram illustrating coated articles before and after heat treatment.

0021<figref idref="f0003">FIGURE 3</figref> is an XPS graph illustrating chemical elements in a pre-HT coated article.

0022<figref idref="f0003">FIGURE 4</figref> is an XPS graph illustrating chemical elements in the coated article of <figref idref="f0003">Fig. 3</figref>, after the coated article of <figref idref="f0003">Fig. 3</figref> has been subjected to HT.

0023<figref idref="f0004">FIGURE 5</figref> is a schematic diagram illustrating coated articles before and after heat treatment.

0024<figref idref="f0005">FIGURE 6</figref> is a schematic diagram illustrating coated articles before and after heat treatment.

0025<figref idref="f0006">FIGURE 7</figref> is a schematic diagram illustrating coated articles before and after heat treatment.

0026<figref idref="f0007">FIGURE 8</figref> is a schematic diagram illustrating coated articles according to an embodiment of this invention before and after heat treatment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

0027Referring now more particularly to the accompanying drawings in which like reference numerals indicate like parts or layers throughout the several views.

0028In certain example embodiments of this invention, prior to heat treatment (HT) a coated article includes a layer of or including zirconium nitride on a glass substrate. This may be the only layer on the glass substrate in certain example embodiments, or alternatively other layers may be present. Heat treatment (e.g., thermal tempering) of the coated article causes the zirconium nitride inclusive layer to transform either partially or entirely into a layer of or including zirconium oxide that can be used for scratch resistant purposes.

0029Because the layer(s) comprising zirconium nitride is heated to such a high temperature due to the HT and/or DLC combustion during HT, at least the layer(s) comprising zirconium nitride is transformed due to the high temperature(s) into a new post-HT layer(s) comprising zirconium oxide. The new post-HT layer(s) comprising zirconium oxide may also include nitrogen in certain example embodiments of this invention (e.g., ZrO:N; ZrO₂:N, ZrO_x:N (where x is from 1 to 3, more preferably from 1.5 to 2.5), and/or any other suitable stoichiometry). The new post-HT layer(s) comprising zirconium oxide (optionally with nitrogen) is surprisingly scratch resistant. Thus, it can be seen that a technique has been provided which allows for a heat treatable scratch resistant product to be made; and the coated article may also have good transmission properties. In certain example embodiments, the scratch resistance of the post-HT coated article may even be better than that of non-HT DLC.

0030In certain example embodiments of this invention, the post-HT layer(s) comprising zirconium oxide includes a nanocrystalline cubic lattice structure. The entire layer(s) may be of a nanocrystalline cubic lattice structure type, or alternatively only part of the layer(s) may include nanocrystalline cubic lattice structure. Zirconium nitride typically does not grow in cubic phase unless at a temperature of at least about 2,000 degrees C. The ZrN pre-HT is typically not in cubic lattice form. Since the HT is only at a temperature of no greater than about 900 degrees C (more preferably no greater than about 800 degrees C), one would expect that the pre-HT non-cubic zirconium nitride would not grow in cubic phase during HT. However, it has surprisingly been found that the HT causes at least part of the layer comprising zirconium nitride to be heated sufficiently to cause it to transform into a post-HT layer(s) comprising zirconium oxide which includes a nanocrystalline cubic lattice structure (with or without nitrogen) which is scratch resistant.

0031Thus, it can be seen that in certain example embodiments of this invention the pre-HT zirconium nitride inclusive layer is transformed during HT into a new post-HT layer comprising zirconium oxide including a nanocrystalline cubic lattice structure, even though the temperatures used by the furnace during HT may be less than those required for typically allowing the cubic growth.

0032As a result of the HT, the amount of oxygen in the post-HT zirconium inclusive layer(s) is much higher than the amount of oxygen in the pre-HT zirconium inclusive layer(s). For example, in certain example embodiments of this invention, the post-HT layer(s) comprising zirconium oxide includes at least 5 times as much oxygen as the pre-HT layer(s) comprising zirconium nitride, more preferably at least 10 times as much, and most preferably at least 20 times as much oxygen as the pre-HT layer(s). In certain example embodiments of this invention, the pre-HT layer(s) comprising zirconium nitride includes from about 0-10% oxygen, more preferably from about 0-5% oxygen, and most preferably from about 0-2 % (atomic %) oxygen.

0033In certain example embodiments, at least prior to heat treatment, one or more of the layers comprising zirconium nitride may be doped with fluorine (F) and/or carbon (C). This may be done, for example, by using a gas such as C₂F₆ during sputter-deposition of the layer(s) comprising zirconium nitride. Surprisingly, it has been found that doping the zirconium nitride with F and/or C prior to heat treatment tends to increase the visible transmission of the heat treated coated article. Of course, following heat treatment the layer comprising zirconium oxide may also be doped with F and/or C in a corresponding manner since it was present before HT. This doping of zirconium nitride (and/or zirconium oxide) with F and/or C may be used in conjunction with any embodiment discussed herein.

0034In certain example embodiments of this invention, zirconium nitride inclusive layer 7 (and 7' to be discussed below) may have a density of at least 6 gm/cm³, more preferably at least 7 gm/cm³. Additionally, in certain example embodiments, zirconium nitride layer 7 (and 7') may have an average hardness of at least 650 kgf/mm, more preferably of at least 700 kgf/mm, and/or may have a bond overlap population of at least 0.25 (more preferably at least about 0.30) for strength purposes. In certain example instances, many of the Zr - N bonds in layer 7 (and 7') may be of the covalent type, which are stronger than ionic bonds, for strength purposes. It is also noted that in certain example embodiments of this invention, the ZrN of layer 7 (and 7') may have a melting point of at least 2,500 degrees C, and it may be about 2,980 degrees C in certain example instances. In certain example embodiments of this invention, the zirconium nitride of layer 7 (and 7') may be represented by Zr_xN_y, where the ratio x:y is from 0.8 to 1.2, and is preferably about 1.0 in certain example embodiments.

0035For purposes of example only, certain example thicknesses for the pre-HT layers shown on the left side of <figref idref="f0001">Fig. 1</figref> are set forth below, with the layers being listed in order from the glass substrate outwardly. <tables id="tabl0001" num="0001"><table frame="none"><title>Example Coating (Fig. 1) - Layer Thicknesses (Pre-HT)</title><tgroup cols="4" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="29mm" /><colspec colnum="2" colname="col2" colwidth="19mm" /><colspec colnum="3" colname="col3" colwidth="26mm" /><colspec colnum="4" colname="col4" colwidth="26mm" /><thead><row><entry valign="top">Layer</entry><entry valign="top">General</entry><entry valign="top">More Preferred</entry><entry valign="top">Most Preferred</entry></row></thead><tbody><row><entry>Dielectric (layer 3)</entry><entry>50-500 Å</entry><entry>100-300 Å</entry><entry>180-220 Å</entry></row><row><entry>DLC (layer 5)</entry><entry>10-300 Å</entry><entry>15-100 Å</entry><entry>20-45 Å</entry></row><row><entry>ZrN (layer 7)</entry><entry>40-500 Å</entry><entry>50-400 Å</entry><entry>90-220 Å</entry></row><row><entry>DLC (layer 9)</entry><entry>20-300 Å</entry><entry>30-100 Å</entry><entry>40-65 Å</entry></row></tbody></tgroup></table></tables>

0036Once the pre-HT coated article shown on the left side of <figref idref="f0001">Fig. 1</figref> is formed, it may or may not be subjected to heat treatment sufficient for at least one of heat bending, thermal bending, and/or heat strengthening.

0037Referring to <figref idref="f0001">Fig. 1</figref>, when subjected to HT (e.g., in a furnace using temperature(s) of from 550 to 800 degrees C, more preferably from 580 to 800 degrees C), the upper or outer DLC inclusive layer 9 bums off due to combustion because of the high temperatures used during HT. In particular, at least hydrogenated DLC layer 9 acts as a fuel which upon combustion with oxygen from the atmosphere during HT produces carbon dioxide and water. This exothermic reaction, caused by combustion of hydrogenated carbon from at least DLC layer 9, causes spontaneous propagation of a combustion wave through the initial reactants. The high temperature developed during this combustion heats the layer 7 comprising zirconium nitride to a temperature(s) well above the heat treating temperature used by the furnace. For example, the combustion of the DLC 9 may heat part of all of the layer 7 comprising zirconium nitride to a temperature of at least about 1200 degrees C, more preferably at least about 1500 degrees C, and most preferably at least about 2,000 degrees C.

0038Because the layer comprising zirconium nitride 7 is heated to such a high temperature due to the DLC combustion during HT, the layer comprising zirconium nitride 7 is transformed during the HT into a new post-HT layer comprising zirconium oxide 11. The new post-HT layer comprising zirconium oxide 11 may also include nitrogen (and/or other dopants) in certain example embodiments of this invention (e.g., ZrO:N; ZrO₂:N; or any other suitable stoichiometry). The new post-HT layer comprising zirconium oxide 11 (optionally with nitrogen) is surprisingly scratch resistant thereby providing a heat treated scratch resistant coated article. It is noted that the phrase "zirconium oxide" as used herein includes ZrO₂ and/or any other stoichiometry where Zr is at least partially oxided. Herein, any description of layer I 1 also may apply to layer 11'; and likewise any description of layer 7 may apply to layer 7'.

0039The post-HT layer comprising zirconium oxide 11 may include from 0-30% nitrogen in certain example embodiments of this invention, more preferably from 0-20% nitrogen, even more preferably from 0-10% nitrogen, and most preferably from about 1-5% nitrogen in certain example embodiments of this invention. The post-HT layer comprising zirconium oxide 11 may include from about 10-70% Zr, more preferably from about 20-60% Zr, even more preferably from about 30-55% Zr, and most preferably from about 30-45% Zr in terms of atomic %. Moreover, the post-HT layer(s) comprising zirconium oxide 11 in certain example embodiments of this invention may include from about 10-85% oxygen, more preferably from about 30-80% oxygen, even more preferably from about 40-70% oxygen, and most preferably from about 50 to 70% oxygen.

0040In certain example embodiments of this invention, the post-HT layer comprising zirconium oxide 11 includes a nanocrystalline cubic lattice structure (although the pre-HT layer comprising zirconium nitride did not in certain instances). As explained above, zirconium nitride typically does not grow in cubic phase unless at a temperature of at least about 2,000 degrees C. It has surprisingly been found that the combustion generated by the DLC during HT causes at least part of the pre-HT layer comprising zirconium nitride 7 to be heated sufficiently to cause it to grow in the cubic phase and become a post-HT layer 11 comprising a nanocrystalline cubic lattice structure including zirconium oxide (with or without nitrogen) which is very scratch resistant in certain example embodiments of this invention.

0041It has surprisingly been found that the use of zirconium nitride (e.g., ZrN) in the pre-HT layer 7 is especially beneficial with respect to allowing a post-HT phase-transformed layer 11 including Zr to be formed which is very scratch resistant.

0042The final HT (or even the non-HT) coated article of <figref idref="f0001">Fig. 1</figref> is scratch resistant and may be used in various applications, including but not limited to IG window units, laminated vehicle windshields, other types of vehicle windows, furniture applications, and/or the like.

0043For purposes of example only, certain example thicknesses for the post-HT coated article shown on the right side of <figref idref="f0001">Fig. 1</figref> are set forth below, with the layers being listed in order from the glass substrate outwardly. <tables id="tabl0002" num="0002"><table frame="none"><title>Example Coating (Fig. 1) - Layer Thicknesses (Post-HT)</title><tgroup cols="4" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="30mm" /><colspec colnum="2" colname="col2" colwidth="19mm" /><colspec colnum="3" colname="col3" colwidth="27mm" /><colspec colnum="4" colname="col4" colwidth="27mm" /><thead><row><entry valign="top">Layer</entry><entry valign="top">General</entry><entry valign="top">More Preferred</entry><entry valign="top">Most Preferred</entry></row></thead><tbody><row><entry>Dielectric (layer 3)</entry><entry>50-500 Å</entry><entry>100-300 Å</entry><entry>180-220 Å</entry></row><row><entry>DLC (layer 5)</entry><entry>0-300 Å</entry><entry>15-100 Å</entry><entry>20-45 Å</entry></row><row><entry>ZrO:N (layer 11)</entry><entry>50-800 Å</entry><entry>70-600 Å</entry><entry>100-350 Å</entry></row></tbody></tgroup></table></tables>

0044It can be seen from the above that post-HT Zr inclusive layer 11 is typically thicker than is pre-HT Zr inclusive layer 7. In other words, the thickness of the Zr inclusive layer increases during HT. In certain example embodiments of this invention, the thickness of the Zr inclusive layer (e.g., from layer 7 to layer 11) may increase at least about 5% during or due to HT, more preferably at least about 10%, and most preferably at least about 40%. This increase in thickness is caused by the transformation of layer 7 into layer 11, where oxygen migrates into the post-HT layer 11 (i.e., more oxygen migrates into the post-HT layer 11 than nitrogen leaves in terms of atomic % and/or size).

0045<figref idref="f0007">Fig. 8</figref> is a cross sectional view of another example embodiment of this invention. The <figref idref="f0007">Fig. 8</figref> embodiment is similar to the <figref idref="f0005">Fig. 6</figref> and <figref idref="f0006">Fig. 7</figref> embodiments, except for the omission of the DLC layers 5, 9. Thus, in the <figref idref="f0007">Fig. 8</figref> embodiment, the layer 7 comprising zirconium nitride may be located directly on the glass substrate 1 before HT. As with the other embodiments discussed herein, the zirconium nitride 7 may be doped with F and/or C in certain example embodiments of this invention, and thus the heat treated zirconium oxide 11 may be doped with F and/or C in a similar manner. In the <figref idref="f0007">Fig. 8</figref> embodiment, it has been found that it has been surprisingly helpful to make the zirconium nitride inclusive layer 7 somewhat thicker. In particular, in the <figref idref="f0007">Fig. 8</figref> embodiment for example layer 7 may be from about 150-400 Å thick, more preferably from about 200-320 Å thick. If the layer 7 is thicker than this, then visible transmission may suffer, whereas if the thickness is lower than this then stain resistance (i.e., resistance to corrosion of the coated article) may suffer following HT. Zirconium nitride inclusive layer 7 may be deposited on substrate 1 by sputtering a Zr or Zr inclusive target in certain example embodiments of this invention.

0046The <figref idref="f0007">Fig. 8</figref> embodiment has been found to be advantageous in that a wider process window for tempering may be possible since samples that have been over-cooked during HT have not shown streaks or haze in contrast with DLC inclusive embodiments discussed herein. Thus, the <figref idref="f0007">Fig. 8</figref> embodiment may ease tolerance requirements in the manufacturing process. Moreover, in the <figref idref="f0007">Fig. 8</figref> embodiment, it has been found that surface treatment (e.g., mechanical buffing) improves the scratch resistance of post-HT zirconium oxide based layer 11.

0047As an alternative of the <figref idref="f0007">Fig. 8</figref> embodiment, an underlayer (not shown in <figref idref="f0007">Fig. 8</figref>) may be provided between the zirconium nitride layer 7 and the substrate 1. This underlayer may be of, or include, a material such as silicon oxide (e.g., SiO₂) or silicon nitride. This underlayer is similar to dielectric layer 3 shown in <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">2</figref> and <figref idref="f0004">5</figref> for example.

0048In any of the example embodiments discussed above, one or more of the layers comprising zirconium nitride (7 and/or 7') may be doped with fluorine (F) and/or carbon (C). This may be done, for example, by using a gas such as C₂F₆ during sputter-deposition of the layer(s) comprising zirconium nitride. For instance, a layer of ZrN:F (7 and/or 7') may be formed by sputtering a Zr inclusive target(s) in an atmosphere including a mixture of N₂ and C₂F₆ gases (Ar gas may also be used in certain example instances in addition to N₂ and C₂F₆ gases). When C₂F₆ gas is used in the sputtering atmosphere, the resulting layer comprising ZrN is typically doped with both F and C since both are present in the gas. Other gases could instead be used.

0049Surprisingly, it has been found that doping the zirconium nitride (7 and/or 7') with F and/or C prior to heat treatment tends to increase the visible transmission of the heat treated coated article. Doping with F and C unexpectedly results in a film with lower absorption compared to undoped films. Moreover, it has been found that the addition of F and/or C to these layers does not significantly change the optics of the coated article, or the biaxial film stress of the films prior to HT. Furthermore, when F and/or C are provided in layer 7 and/or 7', both scratch resistance and environmental stability (e.g., measured via salt fog test) of the HT product are substantially unaffected by the presence of F and/or C. Of course, following heat treatment the layer comprising zirconium oxide (11 and/or 11') may also be doped with F and/or C in a corresponding manner since it was present before HT. This doping of zirconium nitride (and/or zirconium oxide) with F and/or C may be used in conjunction with any embodiment discussed herein.

0050In certain example embodiments of this invention, one or more of layers 7, 7', 11 and 11' may be doped with from about 0.01 to 10.0% F, more preferably from about 0.1 to 8.0% F, even more preferably from about 0.3 to 5.0% F, still more preferably from about 0.4 to 2% F, and most preferably from about 0.5 to 1.0% F (in terms of atomic percent). Moreover, in certain example embodiments of this invention, one or more of layers 7, 7', 11 and 11' may be doped with from about 0.01 to 10.0% C, more preferably from about 0.1 to 8.0% C, even more preferably from about 0.3 to 5.0% C, still more preferably from about 0.4 to 2% C, and most preferably from about 0.5 to 1.0% C (in terms of atomic percent). The doping with F and C may be used together so that one or more of layers 7, 7', 11 and 11' is/are doped with both F and C in these amounts. Alternatively, only one of the dopants F and C may be used for a layer. Thus, in such alternative embodiments, one or more of layers 7, 7', 11 and 11' may be doped with F in the aforesaid amount(s), but not doped with C. As yet another alternative, one or more of layers 7, 7', 11 and 11' may be doped with C in the aforesaid amount(s), but not doped with F.

0051Each of the aforesaid embodiments provides for a heat treatable coated article that is very scratch resistant following HT. For example, post-HT coated articles according to certain embodiments of this invention may have a critical scratch load using an alumina sphere of at least about (15 lbs.) 6.8 kg, more preferably at least (18 lbs.) 8.2 kg, even more preferably at least (20 lbs.)9.1 , still most preferably at least (22.5 lbs.) 10.2 kg, and most preferably at least (30 lbs) 13.6. Additionally, coated articles according to certain example embodiments of this invention are UV stable, and do not significantly degrade upon UV exposure. In certain example embodiments, coated articles herein may have a post-HT contact angle θ with a sessile drop of water of from about 25 to 60 degrees; and sometimes the contact angle is less than 35 degrees.

0052Moreover, in certain example embodiments, good optics are provided in that no significant yellow tint is present post-HT even though yellowish DLC may have been present at least in the pre-HT version of the product. The resulting heat treated coated article is surprisingly transmissive to visible light. For example, the heat treated coated article may have a visible transmission of at least 50%, more preferably of at least 60%, even more preferably of at least 70%, more preferably at least 75%, and sometimes at least 80% according to certain example embodiments of this invention. According to certain example embodiments of this invention, post-HT coated articles have a transmissive a* value of from -5 to +2, more preferably from -4 to 0, and most preferably from -3.5 to -1; and a transmissive b* value of from -8 to +8, more preferably from -3 to +3, and most preferably from -2 to +2. In other words, heat treated coated articles according to certain example embodiments of this invention visually appear very similar to clear uncoated glass, even though the numerous layers for durability purposes are provided thereon.

0053Another unique aspect of certain example embodiments of this invention is the extreme increase in visible transmission caused by heat treatment. In certain example embodiments, visible transmission increases by at least about 20 visible transmission % due to HT, more preferably at least 30%, and most preferably at least 40%. For example, in certain examples of this invention that have been made, the pre-HT visible transmission has been about 36-37%. Following heat treatment for about 400 seconds at about 640 degrees C, the post-HT visible transmission was about 77-81%. In each case, the visible transmission increased by about 40-45% due to HT. For purposes of example and understanding, if a pre-HT coated article had a visible transmission of 36% and following HT the post-HT coated article had a visible transmission of 80%, then the visible transmission increased 44% (i.e., 80% - 36% = 44%) due to HT. The apparent reason for this significant increase in visible transmission due to HT is the vanishing of at least some DLC due to HT because of the aforesaid combustion thereof. DLC blocks visible transmission to some extent, and its combustion and disappearance during HT allows visible transmission of the resulting HT coated article to significantly increase as shown above. Thus, not only does the DLC combustion act as a fuel which allows transformation of the Zr inclusive layer, but it also allows visible transmission to significantly increase.

0054Any suitable type of glass substrate 1 may be used in different embodiments of this invention. For example, various types of soda lime silica glass or borosilicate glass may be used for substrate 1. However, in certain example embodiments of this invention, the coating of any of the aforesaid embodiments may be supported by a special type of glass substrate that has a very high visible transmission and a very clear color. In particular, in such certain example embodiments of this invention, the glass substrate 1 may be any of the glasses described in commonly owned <patcit id="pcit0017" dnum="US2004121826A"><text>US 2004/121826</text></patcit>. In certain preferred embodiments, the resulting glass has visible transmission of at least 85%, more preferably at least 88%, and most preferably at least 90% (e.g., at a reference thickness of about 0.219 inches or 5.56 mm). The advantage of using such a glass substrate 1 is that the resulting HT product is caused to have a visual appearance similar to that of uncoated clear glass - even though the coating is provided thereon. In addition to the base glass, examples of the glass batch and/or final glass are set forth below (in terms of weight percentage of the total glass composition, unless otherwise listed as ppm): <tables id="tabl0003" num="0003"><table frame="none"><title>Example Colorants and Oxidizer Cerium in Glass Substrate</title><tgroup cols="5" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="30mm" /><colspec colnum="2" colname="col2" colwidth="25mm" /><colspec colnum="3" colname="col3" colwidth="25mm" /><colspec colnum="4" colname="col4" colwidth="27mm" /><colspec colnum="5" colname="col5" colwidth="25mm" /><thead><row><entry valign="top">Ingredient</entry><entry valign="top">General</entry><entry valign="top">Preferred</entry><entry valign="top">More Preferred</entry><entry valign="top">Best</entry></row></thead><tbody><row><entry>total iron (Fe₂O₃):</entry><entry>0.01 - 0.20 %</entry><entry>0.01 - 0. 15 %</entry><entry>0.02-0.12%</entry><entry>0.03 to 0.10 %</entry></row><row><entry>cobalt oxide:</entry><entry>0 to 15 ppm</entry><entry>0.1 to 10 ppm</entry><entry>0.5 to 5 ppm</entry><entry>0.5 to 3 ppm</entry></row><row><entry>cerium oxide:</entry><entry>0.005 - 1.0 %</entry><entry>0.01 - 1.0 %</entry><entry>0.01 - 0.5 %</entry><entry>0.05 to 0.2 %</entry></row><row><entry>erbium oxide:</entry><entry>0 to 1.0 %</entry><entry>0.01 - 0.30 %</entry><entry>0.02-0.20%</entry><entry>0.02 to 0.15 <i>%</i></entry></row><row><entry>titanium oxide:</entry><entry>0 to 0.5%</entry><entry>0 to 0.2%</entry><entry>0.001 to 0.05%</entry><entry>0.01 to 0.02%</entry></row><row><entry>chromium oxide:</entry><entry>0 to 10 ppm</entry><entry>0 to 8 ppm</entry><entry>0 to 5 ppm</entry><entry>1 to 5 ppm</entry></row><row><entry>glass redox:</entry><entry>&lt;= 0.20</entry><entry>&lt;= 0.12</entry><entry>&lt;= 0.10</entry><entry>&lt;= 0.08</entry></row><row><entry>% FeO:</entry><entry>0.0001-0.05%</entry><entry>0.0001-0.01%</entry><entry>0.001-0.008%</entry><entry>0.001-0.003%</entry></row></tbody></tgroup></table></tables>

0055It is noted that in other embodiments of this invention, additional layers (not shown) may be added to the coated articles discussed above, and/or certain layer(s) may be deleted.

REFERENCE EXAMPLE 1

0056This Example 1 is similar to the <figref idref="f0004">Fig. 5</figref> embodiment.

0057The glass substrate 1 was cleaned/washed. It was then ion beam etched using argon gas to clean the surface thereof. Then, a silicon nitride barrier layer 3 (doped with Al) about 100 Å thick, a DLC (ta-C:H type) layer 5 about 70 Å thick, a zirconium nitride layer 7' about 100 Å thick, another DLC (ta-C:H type) layer 5' about 70 Å thick, another zirconium nitride layer 7 about 100 Å thick, and a sacrificial outer DLC (ta-C:H type) layer 9 about 70 Å thick were formed on a glass substrate (see <figref idref="f0004">Fig. 5</figref>). The ZrN layers 7 and 7' were formed via sputtering a Zr target in an atmosphere including N and Ar, and the DLC layers were formed via ion-beam deposition using an anode-cathode voltage of about 3,000 V and acetylene feedstock gas.

0058<figref idref="f0003">Fig. 3</figref> is an XPS graph illustrating the pre-HT chemical make-up of the coated article according to this Example. As can be seen in <figref idref="f0003">Fig. 3</figref>, the carbon (C) spikes indicate the DLC layers 5 and 5', whereas the Zr spikes indicate the ZrN layers 7 and 7'. It is noted that the C content increases on the left edge of the <figref idref="f0003">Fig. 3</figref> graph showing the thin DLC sacrificial layer 9 at the outermost layer of the pre-HT coating. The high oxygen content on the right side of the graph indicates the glass substrate, and the combination of the Si and N spikes in the same area indicates the optional silicon nitride barrier layer 3.

0059The coated article of Example 1 was then subjected to HT at about 625 degrees C for about four minutes.

0060<figref idref="f0003">Fig. 4</figref> is an XPS graph of the coated article of <figref idref="f0003">Fig. 3</figref> (i.e., of this Example 1) after the HT. <figref idref="f0003">Fig. 4</figref> illustrates that the overcoat DLC layer 9 burned off during HT due to combustion, and that pre-HT layers 5, 7', 5' and 7 merged or were transformed into a thick layer consisting essentially of scratch resistant zirconium oxide 11 that was slightly doped with nitrogen (see the right-hand coated article in <figref idref="f0004">Fig. 5</figref> which is the post-HT article). It can be seen in <figref idref="f0003">Fig. 4</figref> that residual carbon is left over in the zirconium oxide layer 11 due to the previous DLC layers which were present prior to heat treatment.

REFERENCE EXAMPLE 2

0061Example 2 was made in accordance with the <figref idref="f0005">Fig. 6</figref> embodiment. On a 10 mm thick clear glass substrate having a composition similar to that discussed above, layers 5, 7 and 9 were formed as shown in <figref idref="f0005">Fig. 6</figref>. DLC layer 5 was 34 Å thick, ZrN layer 7 was 160 Å thick, and DLC layer 9 was 100 Å thick. The two DLC layers were formed via ion beam deposition using acetylene gas, while the zirconium nitride layer 7 was formed via sputtering using a power of about 3 kW. Following heat treatment, the coated article included substrate 1 and zirconium oxide layer 11 that included some nitrogen as shown on the right side of <figref idref="f0005">Fig. 6</figref>.

0062Following HT, based on three different samples of this example, the coated article of this example on average had a visible transmission of about 78.61%, a critical scratch load (CSL) of 31 lbs. and a haze value of 1.6.

REFERENCE EXAMPLE 3

0063Example 3 was made in accordance with the <figref idref="f0006">Fig. 7</figref> embodiment. On a 10 mm thick clear glass substrate 1 having a composition similar to that discussed above, layers 7 and 9 were formed as shown in <figref idref="f0006">Fig. 7</figref>. ZrN layer 7 was 160 Å thick, and DLC layer 9 was from 60-100 Å thick. As with other examples, the zirconium nitride layer was formed by sputtering. Following heat treatment, the coated article included substrate 1 and zirconium oxide layer 11 that included some nitrogen as shown on the right side of <figref idref="f0006">Fig. 7</figref>.

0064Following HT, based on three different samples of this example, the coated article of this example on average had a visible transmission of about 81.35%, a critical scratch load (CSL) of 10.8 lbs. and a haze value of 0.44.

0065In certain example non-limiting embodiments of this invention, coated articles following HT may have a visible transmission of at least 70%, more preferably of at least 75%. In certain example non-limiting embodiments of this invention, coated articles following HT may have a haze value of no greater than 2.5, more preferably no greater than 1.75, and sometimes no greater than 1.0.

EXAMPLE 4

0066In Example 4, a coated article was made in accordance with the <figref idref="f0007">Fig. 8</figref> embodiment. A ZrN layer 7 was sputter deposited directly on a glass substrate using a Zr target in an atmosphere including Ar and N gases, to a thickness of about 326 angstroms. The Ar gas flow per cathode was 190 sccm, the N₂ gas flow per cathode was 79.2 sccm, the operating pressure in the sputtering chamber was (2.4 mTorr) 0.032 Pa, and the N₂/power ratio was about 6.1. The glass substrate was clear glass about 6 mm thick. As coated, prior to heat treatment, the coated article had a visible transmission of about 38%. The coated article was then heat treated in a box oven furnace for about 4-5 minutes, and following heat treatment mechanical buffing using greater than (10 lbs) 4.5 kg of pressure was performed on the outer surface of the zirconium oxide based layer 11. The heat treatment caused the zirconium nitride based layer 7 to transform into a zirconium oxide based layer 11. Following the heat treatment, the coated article had a visible transmission of about 79%. There were no signs of streaks of haze following the heat treatment, and scratch resistance was good.

0067With respect to any embodiment herein, the glass substrate may be ion beam milled prior to deposition of a coating thereon. For example, a step of ion beam milling the glass substrate 1 (e.g., the non-tin surface thereof) may be performed so as to remove at least 2 Å (more preferably at least 5 Å, and most preferably at least 10 Å) of glass from at least a portion (and possibly the entire) glass substrate surface. Then, after the ion beam milling of the glass substrate 1, the base layers 3, 5 and/or 7 and then the other layers are deposited on the ion beam milled surface of the glass substrate 1. For example, glass substrate 1 may be ion beam milled using any technique for ion beam milling described in <patcit id="pcit0018" dnum="US6777030B"><text>U.S. Patent No. 6,777,030</text></patcit> and/or 6,740,211.

0068While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.