Carbon film coated glass

Abstract: Carbon film coated glass is disclosed which includes a glass substrate, an intermediate layer formed on a surface of the glass substrate in a thickness of 50 angstroms or more and including metallic oxide in an amount of 5% or more by mole and balance of carbon at least, and a carbon film formed on a surface of the intermediate layer in a thickness of 10 angstroms or more. The intermediate layer closely binds the glass substrate and the carbon film together, and thereby it inhibits the carbon film from coming off. The carbon film coated glass is thus improved in the durability. Additionally, the carbon film can include fluorine which is combined with its surface at least, and thereby it improves the repellency of the carbon film coated glass as well as the transparency thereof.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to carbon film coated glass which is applicable, for instance, to repellent glass, a reactor, such as a reactor pipe and so on, or the like. Description of the Related Art As disclosed in Japanese Unexamined Patent Publication (Kokai) No. 188,447/1990, carbon film coated glass, which is utilized, for example, as a reactor pipe, has been known. This conventional carbon film coated glass comprises quartz glass and a carbon film which is formed on a surface of the quartz glass. The carbon film coated glass is produced by supplying a carrier gas which includes a raw material adapted for forming a carbon film onto the surface of the quartz glass. The quartz glass has been reduced with a hydrogen gas in advance. The conventional carbon film coated glass, however, has drawbacks in that the adhesion between the carbon film and the quartz glass is insufficient, and in that the carbon film is likely to come off accordingly. Hence, the conventional carbon film coated glass has been lacking durability. In addition, the conventional carbon film coated glass sometimes suffers from insufficient repellency in certain applications. In DE-A-3 316 693 a method for the production of a glass coated with a carbon film in which adhesion of the carbon film to the glass substrate shall be improved by depositing an intermediate layer of a siloxane or silazane polymer. A first aspect of the present invention has been developed in view of the drawbacks of the conventional carbon film coated glass. It is an object of the first aspect of the present invention to provide carbon film coated glass whose carbon film is less likely to come off. Further, a second aspect of the present invention has been developed also in view of the drawbacks of the conventional carbon film coated glass. It is an object of the second aspect of the present invention to provide carbon film coated glass whose repellency is held to a sufficient extent and at the same time whose carbon film is less likely to come off. The first aspect of carbon film coated glass according to the present invention comprises: a glass substrate; an intermediate layer formed on a surface of the glass substrate in a thickness of 5 nm (50 angstroms) or more and consisting of metallic oxide, carbon and optionally reaction products thereof, and optionally fluorine wherein the metal content defined as oxide equivalent is 5 mole % or more, and a carbon film formed on the surface of the intermediate layer in a thickness of 1 nm (10 angstroms) or more. Further, according to the second aspect of carbon film coated glass according to the present invention said carbon film further contains fluorine at least in a film portion thereof extending from a film surface, or contains fluorine through the entire film thickness. As the glass substrate, it is possible to employ a glass substrate which includes oxide glass such as silicate glass, borosilicate glass, soda-lime glass, flint glass, or the like. This glass substrate can be in a variety of shapes such as a plate-like shape, a pipe-like shape, and so on. As the metallic oxide of the intermediate layer, it is possible to employ one or more of the following metallic oxides: SiO₂, TiO₂, ZrO₂, Y₂O₃, Al₂O₃, PbO, CaO, MgO, B₂O₃, Fe₂O₃, Na₂O, K₂O, Li₂O, and so on. This intermediate layer includes the metallic oxide in an amount of 5 mole % or more. When the intermediate layer includes the metallic oxide in an amount of less than 5 mole %, the adhesion between the glass substrate and the intermediate layer, and the adhesion between the intermediate layer and the carbon film or the fluorine-including carbon film are insufficient. Here, the amount can be derived from the mole fraction which expresses a composition of a material mixture. Namely, the mole fraction is the ratio of the number of moles of a component in a material mixture to the total number moles of all the components in the material mixture, and accordingly the sum of the moles fractions of all the components in the material mixture is 1 (i.e., 100% by mole). This mole fraction can be calculated as follows. For instance, let the present intermediate layer which includes the carbon and the metallic oxide be a material mixture. When the atomic percentage (or atomic %) of either one of the carbon and the metallic oxide is known, the mole fraction of the other component can be derived therefrom. Further, let the present fluorine-including carbon film be a material mixture. When the atomic % of either one of the carbon and the fluorine is known, the mole fraction of the other component can be derived therefrom. As the intermediate layer, an intermediate layer is employed consisting of metallic oxide, carbon and optionally reaction products thereof, and optionally fluorine. It is preferred to employ an intermediate layer which includes fluorine, since such a construction further gives repellency which results from the fluorine even after the carbon film or the fluorine-including carbon film is worn out. Furthermore, in order to further improve the adhesion between the intermediate layer and the carbon film or the fluorine-including carbon film, it is preferred to employ an intermediate layer in which the atomic % of the carbon increases with respect to that of the metallic oxide as the intermediate layer approaches the outermost surface. This intermediate layer is formed on a surface of the glass substrate in a thickness of 5 nm (50 angstroms) or more. When the thickness of the intermediate layer is less than 5 nm (50 angstroms), the adhesion between the glass substrate and the intermediate layer, and the adhesion between the intermediate layer and the carbon film or the fluorine-including carbon film is insufficient, and accordingly such a thickness adversely affects the repellency, for instance. This intermediate layer can be formed by physical vacuum deposition (hereinafter abbreviated to PVD), chemical vacuum deposition (hereinafter abbreviated to CVD), or the like. In particular, it is preferred to form the intermediate layer by PVD in view of the adhesion improvement. In the first aspect of the carbon film coated glass according to the present invention, the carbon film includes carbon at least. In the second aspect of the carbon film coated glass according to the present invention, the fluorine-including carbon film is a carbon film which is combined with fluorine in its surface at least, that is, wherein the carbon film contains fluorine at least in a film portion thereof extending from the film surface or through the entire film thickness. The carbon film and the fluorine-including carbon film are formed on a surface of the intermediate layer in a thickness of 1 nm (10 angstroms) or more. When the thickness of the carbon film and the fluorine-including carbon film is less than 1 nm (10 angstroms), the carbon included in the carbon film and the fluorine-including carbon film is less likely to effect its functions such as the wear resistance or the like. The carbon film and the fluorine-including carbon film can be formed by PVD, CVD, or the like. In particular, it is preferred to form the carbon film and the fluorine-including carbon film by PVD in view of the adhesion improvement. The fluorine-including carbon film can be formed by PVD in which a gas containing fluorine, such as a CF₄ gas or the like, is employed. In this way, a surface fluorination treatment can be carried out during PVD. In the case that PVD is employed, the intermediate layer and the carbon film or the fluorine-including carbon film can be formed continuously by adapting the metallic oxide and the carbon to be targets or evaporation sources and by varying sputtering electric power or the like as time elapses. When the intermediate layer and the carbon film or the fluorine-including carbon film are formed continuously by radio frequency (hereinafter abbreviated to RF) sputtering, RF electric power is varied. Further, when the intermediate layer and the carbon film or the fluorine-including carbon film are formed continuously by PVD, electron beam (hereinafter abbreviated to EB) current or resistance heating current is varied. Furthermore, when the intermediate layer and the carbon film or the fluorine-including carbon film are formed continuously by direct current (hereinafter abbreviated to DC) sputtering, DC current is varied. In the carbon film coated glass according to the present invention, micro-fine convexes and concaves which result from the carbon particles deposited on the surface shed water or the like which is present on the surface, and thereby the water or the like is made into droplets because of the surface tension. Thus, the present carbon film coated glass repels the water or the like. Accordingly, the present carbon film coated glass can be adapted to be repellent glass which is applicable to automobile windshield glass or the like. If such an application is desired, the carbon film coated glass is adapted to be transparent repellent glass by employing the following construction. Namely, if such is the case, a transparent glass substrate is employed, the kind of the metallic oxide to be employed is selected, the mole percentages of the metallic oxide and the carbon in the intermediate layer and the carbon film or the fluorine-including carbon film are adjusted, and the thicknesses of the intermediate layer and the carbon film or the fluorine-including carbon film are adjusted so that the present carbon film coated glass exhibits a predetermined transparency. Moreover, the present carbon film coated glass can be adapted to be a reactor pipe or the like into which a gas or the like is introduced and the gas or the like is reacted with carbon or the like. In the first aspect of the carbon film coated glass according to the present invention, since there is provided the intermediate layer between the glass substrate and the carbon film and since the intermediate layer adheres closely to the glass substrate and the carbon film, the intermediate layer works as a binder layer which binds the glass substrate and the carbon film together. Therefore, it is believed that the intermediate layer inhibits the carbon film from coming off. Further, in the second aspect of the carbon film coated glass according to the present invention, since the fluorine-including carbon film is employed which is combined with fluorine in its surface at least, the repellency can be improved. Likewise, in the second aspect of the carbon film coated glass, since there is provided the intermediate layer between the glass substrate and the fluorine-including carbon film and since the intermediate layer adheres closely to the glass substrate and the fluorine-including carbon film, not only the intermediate layer keeps the improved water repellency, but also it inhibits the fluorine-including carbon film from coming off, as described above. In particular, when the intermediate layer is formed by PVD or CVD, the metal atoms and the carbon atoms are activated during the vapor deposition process so that metal-carbon (M-C) bonds are more likely to form between the metal atoms and the carbon atoms. As a result, a firmer intermediate layer can be formed. As having been described so far, in the first and second aspects of the carbon film coated glass according to the present invention, since there is provided the intermediate layer between the glass substrate and the carbon film or the fluorine-including carbon film, the carbon film or the fluorine-including carbon film is less likely to come off. Especially, in the second aspect of the carbon film coated glass according to the present invention, the fluorine-including carbon film is employed which is combined with fluorine in its surface at least, the carbon film coated glass can be improved in the repellency. Since the present carbon film coated glass has an excellent durability as described above, repellent glass, a reactor pipe, or the like, to which the present carbon film coated glass is applied, can be used for a long period of time. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the present invention and many of its advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings and detailed specification, all of which forms a part of the disclosure: Figure 1 is a schematic cross sectional view of First through Seventh Preferred Embodiments of carbon film coated glass according to the present invention; Figure 2 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the First Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 3 is a graphic representation of results of the Auger electron spectroscopy (hereinafter abbreviated to AES) carried out onto the First Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 4 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Second Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 5 is a graphic representation of results of the AES carried out onto the Second Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 6 is a graphic representation of results of the AES carried out onto Comparative Example of carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 7 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Third Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 8 is a graphic representation of results of a test specimens evaluation, and shows a relationship between intermediate layer thickness and contact angle; Figure 9 is a graphic representation of another results of the test specimens evaluation, and shows a relationship between SiO₂ mole percentage in intermediate layer and contact angle after a wear test; Figure 10 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Fourth Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 11 is a graphic representation of results of the AES carried out onto the Fourth Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 12 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Fifth Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 13 is a graphic representation of results of the AES carried out onto the Fifth Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 14 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Sixth Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 15 is a graphic representation of results of the AES carried out onto the Sixth Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 16 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Seventh Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 17 is a graphic representation of results of the AES carried out onto the Seventh Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 18 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Eighth Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 19 is a graphic representation of results of the AES carried out onto the Eighth Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 20 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Ninth Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 21 is a graphic representation of results of the AES carried out onto the Ninth Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 22 is a graph which illustrates a relationship between time and RF electric powers applied to targets when producing the Tenth Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 23 is a graphic representation of results of the AES carried out onto the Tenth Preferred Embodiment of the carbon film coated glass, and shows a relationship between etching time and atomic percentages; Figure 24 is an enlarged schematic cross sectional view of the First through Third Preferred Embodiments of the carbon film coated glass according to the present invention; Figure 25 is an enlarged schematic cross sectional view of the Fourth through Seventh Preferred Embodiments of the carbon film coated glass according to the present invention; Figure 26 is a schematic cross sectional view of the Eighth Preferred Embodiment of the carbon film coated glass according to the present invention; Figure 27 is an enlarged schematic cross sectional view of the Eighth Preferred Embodiment of the carbon film coated glass; Figure 28 is a schematic cross sectional view of the Ninth and Tenth Preferred Embodiments of the carbon film coated glass according to the present invention; and Figure 29 is an enlarged schematic cross sectional view of the Ninth and Tenth Embodiments of the carbon film coated glass. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Having generally described the present invention, a further understanding can be obtained by reference to the specific preferred embodiments which are provided herein for purposes of illustration only and are not intended to limit the scope of the appended claims. As illustrated in Figure 1, the First through Eighth Preferred Embodiments of the carbon film coated glass according to the present invention comprise a glass substrate 1, an intermediate layer 2 formed on a surface of the glass substrate 1, and a carbon film 3 formed on a surface of the intermediate layer 2. First Preferred Embodiment The First Preferred Embodiment of the carbon film coated glass according to the present invention was produced as described below. First, two targets, namely a C (carbon) target and an SiO₂ target, were provided in a vacuum chamber of a bipolar RF magnetron sputtering apparatus. The glass substrate 1 was also provided in the vacuum chamber of the sputtering apparatus. The vacuum chamber was evacuated to 2 x 10⁻³ Pa or less, and the glass substrate 1 was heated to 300 °C. Then, an Ar (argon) gas was introduced into the vacuum chamber until a pressure therein became 1 x 10⁻¹ Pa, and RF electric powers (in watt) applied to the C target and the SiO₂ target were varied as time elapsed as illustrated in Figure 2, thereby carrying out film forming by sputtering. Thus, the carbon film coated glass was obtained which had the intermediate layer 2 formed on the glass substrate 1 and the carbon film 3 formed on the intermediate layer 2. This carbon film coated glass was analyzed quantitatively with an AES apparatus for its C, Si and O atomic percentages from its outermost surface in a depthwise direction, and results of this quantitative analysis are shown in Figure 3. Figure 3 illustrates the relationship between etching time (in minute) required for etching the C, Si and O from the surface of the carbon film coated glass and atomic percentages (in atomic %) of the elements. As can be seen from Figure 3, it is understood that the intermediate layer 2 was formed on the glass substrate 1 in a thickness of approximately 40 nm (400 angstroms), and that the carbon film 3 was formed on this intermediate layer 2 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 24, the intermediate layer 2 was formed so that it included an SiO₂ layer 21 which included SiO₂ only was formed on the glass substrate 1 in a thickness of approximately 10 nm (100 angstroms), and a mixture layer 22 which included SiO₂ and C and in which the mole percentage of the C became higher as the outermost surface approached was formed on the SiO₂ layer 21 in a thickness of approximately 30 nm (300 angstroms). Onto this carbon film coated glass, a water droplet was dropped in order to evaluate a contact angle between the carbon film coated glass and the water droplet. The contact angle was found to be approximately 90°. Thus, it is apparent that this carbon film coated glass is applicable to water repellent glass. Further, this carbon film coated glass was worn with a dry flannel cloth under frictional conditions of a load of 2.94 N (300 gf) and 3,000 times of a "to and fro" movement. No change was appreciable on the carbon film 3. Hence, it is understood that this carbon film coated glass was superior in the adhesion of the carbon film 3 and in the durability. Second Preferred Embodiment The Second Preferred Embodiment of the carbon film coated glass according to the present invention was produced in a manner similar to that of the First Preferred Embodiment, however, the RF electric powers are varied as time elapsed in a manner different from that of the First Preferred Embodiment. The other production arrangements were the same as those of the First Preferred Embodiment. Namely, the RF electric powers (in watt) applied to the C target and the SiO₂ target were varied as time elapsed as illustrated in Figure 4, thereby carrying out film forming by sputtering. The thus obtained carbon film coated glass was analyzed quantitatively with the AES apparatus for its C, Si and O atomic percentages from its outermost surface in a depthwise direction. As can be seen from Figure 5, the intermediate layer 2 was formed on the glass substrate 1 in a thickness of approximately 20 nm (200 angstroms), and the carbon film 3 was formed on this intermediate layer 2 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 24, the intermediate layer 2 was formed so that it included an SiO₂ layer 21 which included SiO₂ only was formed on the glass substrate 1 in a thickness of approximately 10 nm (100 angstroms), and a mixture layer 22 which included SiO₂ and C was formed on the SiO₂ layer 21 in a thickness of approximately 10 nm (100 angstroms). Also in this carbon film coated glass, the contact angle was found to be approximately 90°. Likewise, this carbon film coated glass was worn under the same frictional conditions as those described in the First Preferred Embodiment. No change was appreciable also on the carbon film 3. Comparative Example In comparison, a comparative carbon film coated glass was prepared by using a C target only and by carrying out film forming by sputtering at a constant RF electric power of 400 watts. The other production arrangements were the same as those of the First Preferred Embodiment. The thus obtained comparative carbon film coated glass was analyzed quantitatively with the AES apparatus for its C, Si and O atomic percentages from its outermost surface in a depthwise direction. As can be seen from Figure 6, a carbon film was formed substantially directly on a glass substrate in a thickness of approximately 20 nm (200 angstroms). In this comparative carbon film coated glass, the contact angle was found to be approximately 90°, and its water repellency was favorable. However, in this comparative carbon film coated glass, the entire carbon film was come off when the "to and fro" movement was carried out only 50 times, and the contact angle deteriorated to 50°. Third Preferred Embodiment The Third Preferred Embodiment of the carbon film coated glass according to the present invention was produced with an ion plating apparatus which had two evaporation sources, i.e., a C evaporation source and an SiO₂ evaporation source, as described below. First, the C evaporation source and the SiO₂ evaporation source were provided in a vacuum chamber of the ion plating apparatus. The glass substrate 1 was also provided in the vacuum chamber of the ion plating apparatus. The vacuum chamber was evacuated to 2 x 10⁻³ Pa or less, and the glass substrate 1 was heated to 300 °C. Then, an Ar gas was introduced into the vacuum chamber until a pressure therein became 2 x 10⁻² Pa, and an acceleration voltage of - 5 kV was applied to the C evaporation source and the SiO₂ electron beam evaporation source. At the same time, - 50 kV was applied to a DC bias voltage application electrode which was placed above the glass substrate 1. Further, an emission current was varied as time elapsed in order to vary the film forming speeds (in 0,1 nm (angstroms)/second) of C and SiO₂ as illustrated in Figure 7. As a result, plasma discharges were generated, and accordingly film forming was carried out by ion plating. The Third Preferred Embodiment of the carbon film coated glass was thus obtained. Also in this carbon film coated glass, the contact angle was found to be approximately 90°. Likewise, this carbon film coated glass was worn under the same frictional conditions as those described in the First Preferred Embodiment. No change was appreciable also on the carbon film 3. Test Specimens Evaluation A variety of carbon film coated glass test specimens were prepared by varying the RF electric powers (in watt) applied to the C target and SiO₂ target as time elapsed in a manner similar to the Second Preferred Embodiment, however, the film forming was interrupted at various times or prolonged to various times in order to vary the thickness of their intermediate layers 2. The other production arrangements were the same as those of the Second Preferred Embodiment. These carbon film coated glass test specimens were worn under the same frictional conditions as those described in the First Preferred Embodiment, and thereafter their contact angles (in degree) were evaluated. The results of this evaluation are shown in Figure 8. As can be seen from Figure 8, it is understood that the carbon film coated glass exhibited the contact angle which exceeded approximately 70° with respect to water, and that it was superior in the durability when the intermediate layer had a thickness of 5 nm (50 angstroms) or more. Further, a variety of carbon film coated glass test specimens were prepared by varying the RF electric powers (in watt) applied to the C target and SiO₂ target as time elapsed in a manner similar to the Second Preferred Embodiment, however, the film forming was interrupted at various times or prolonged to various times in order to vary the mole percentage of the SiO₂ (in %) in their intermediate layers 2. The other production arrangements were the same as those of the Second Preferred Embodiment. These carbon film coated glass test specimens were worn under the same frictional conditions as those described in the First Preferred Embodiment, and thereafter their contact angles (in degree) were evaluated. The results of this evaluation are shown in Figure 9. As can be seen from Figure 9, it is understood that the carbon film coated glass exhibited the contact angle which exceeded approximately 70° with respect to water, and that it was superior in the durability when the intermediate layer 2 had the SiO₂ mole percentage of 5% or more. In addition, it was found that the carbon film coated glass was superior in the durability even when the intermediate layer included the SiO₂ only. Fourth Preferred Embodiment The Fourth Preferred Embodiment of the carbon film coated glass according to the present invention was produced in a manner similar to that of the First Preferred Embodiment, however, a C target and a TiO₂ target were provided in the vacuum chamber of the sputtering apparatus and the RF electric powers applied to the targets were varied as time elapsed in a manner different from that of the First Preferred Embodiment. The other production arrangements were the same as those of the First Preferred Embodiment. Namely, the RF electric powers (in watt) applied to the C target and the TiO₂ target were varied as time elapsed as illustrated in Figure 10, thereby carrying out film forming by sputtering. The thus obtained carbon film coated glass was analyzed quantitatively with the AES apparatus for its C, Ti, Si and O atomic percentages from its outermost surface in a depthwise direction. As can be seen from Figure 11, the intermediate layer 2 was formed on the glass substrate 1 in a thickness of approximately 30 nm (300 angstroms), and the carbon film 3 was formed on this intermediate layer 2 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 25, the intermediate layer 2 was formed so that it included a first mixture layer 23 which included SiO₂, TiO₂ and C was formed on the glass substrate 1 in a thickness of approximately 6 nm (60 angstroms), and a second mixture layer 24 which included TiO₂ and C was formed on the first mixture layer 23 in a thickness of approximately 24 nm (240 angstroms). In the first and second mixture layers 23 and 24, the mole percentages of the C became higher as outermost surfaces of the first and second mixture layers 23 and 24 approached. It is believed that the SiO₂ included in the first mixture layer 23 because the SiO₂ contained in the glass substrate 1 migrated from the glass substrate 1 to the intermediate layer 2 during the film forming by sputtering. In this carbon film coated glass, the TiO₂ was likely to exhibit an affinity for the SiO₂ in the glass substrate 1. The contact angle of this carbon film coated glass was found to be maintained at approximately 90° even after it was worn under the same frictional conditions as those described in the First Preferred Embodiment. No change was appreciable on the carbon film 3. Fifth Preferred Embodiment The Fifth Preferred Embodiment of the carbon film coated glass according to the present invention was produced in a manner similar to that of the First Preferred Embodiment, however, a C target and a ZrO₂ target were provided in the vacuum chamber of the sputtering apparatus and the RF electric powers applied to the targets were varied as time elapsed in a manner different from that of the First Preferred Embodiment. The other production arrangements were the same as those of the First Preferred Embodiment. Namely, the RF electric powers (in watt) applied to the C target and the ZrO₂ target were varied as time elapsed as illustrated in Figure 12, thereby carrying out film forming by sputtering. The thus obtained carbon film coated glass was analyzed quantitatively with the AES apparatus for its C, Zr, Si and O atomic percentages from its outermost surface in a depthwise direction. As can be seen from Figure 13, the intermediate layer 2 was formed on the glass substrate 1 in a thickness of approximately 30 nm (300 angstroms), and the carbon film 3 was formed on this intermediate layer 2 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 25, the intermediate layer 2 was formed so that it included a first mixture layer 23 which included SiO₂, ZrO₂ and C was formed on the glass substrate 1 in a thickness of approximately 6 nm (60 angstroms), and a second mixture layer 24 which included ZrO₂ and C was formed on the first mixture layer 23 in a thickness of approximately 24 nm (240 angstroms). In the first and second mixture layers 23 and 24, the mole percentages of the C became higher as outermost surfaces of the first and second mixture layers 23 and 24 approached. Also in this carbon film coated glass, the ZrO₂ was likely to exhibit an affinity for the SiO₂ in the glass substrate 1. The contact angle of this carbon film coated glass was found to be maintained at approximately 90° even after it was worn under the same frictional conditions as those described in the First Preferred Embodiment. No change was appreciable on the carbon film 3. Sixth Preferred Embodiment The Sixth Preferred Embodiment of the carbon film coated glass according to the present invention was produced in a manner similar to that of the First Preferred Embodiment, however, a C target and a Y₂O₃ target were provided in the vacuum chamber of the sputtering apparatus and the RF electric powers applied to the targets were varied as time elapsed in a manner different from that of the First Preferred Embodiment. The other production arrangements were the same as those of the First Preferred Embodiment. Namely, the RF electric powers (in watt) applied to the C target and the Y₂O₃ target were varied as time elapsed as illustrated in Figure 14, thereby carrying out film forming by sputtering. The thus obtained carbon film coated glass was analyzed quantitatively with the AES apparatus for its C, Y, Si and O atomic percentages from its outermost surface in a depthwise direction. As can be seen from Figure 15, the intermediate layer 2 was formed on the glass substrate 1 in a thickness of approximately 30 nm (300 angstroms), and the carbon film 3 was formed on this intermediate layer 2 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 25, the intermediate layer 2 was formed so that it included a first mixture layer 23 which included SiO₂, Y₂O₃ and C was formed on the glass substrate 1 in a thickness of approximately 6 nm (60 angstroms), and a second mixture layer 24 which included Y₂O₃ and C was formed on the first mixture layer 23 in a thickness of approximately 24 nm (240 angstroms). In the first and second mixture layers 23 and 24, the mole percentages of the C became higher as outermost surfaces of the first and second mixture layers 23 and 24 approached. Also in this carbon film coated glass, the Y₂O₃ was likely to exhibit an affinity for the SiO₂ in the glass substrate 1. The contact angle of this carbon film coated glass was found to be maintained at approximately 90° even after it was worn under the same frictional conditions as those described in the First Preferred Embodiment. No change was appreciable on the carbon film 3. Seventh Preferred Embodiment The Seventh Preferred Embodiment of the carbon film coated glass according to the present invention was produced in a manner similar to that of the First Preferred Embodiment, however, a C target and an Al₂O₃ target were provided in the vacuum chamber of the sputtering apparatus and the RF electric powers applied to the targets were varied as time elapsed in a manner different from that of the First Preferred Embodiment. The other production arrangements were the same as those of the First Preferred Embodiment. Namely, the RF electric powers (in watt) applied to the C target and the Al₂O₃ target were varied as time elapsed as illustrated in Figure 16, thereby carrying out film forming by sputtering. The thus obtained carbon film coated glass was analyzed quantitatively with the AES apparatus for its C, Al, Si and O atomic percentages from its outermost surface in a depthwise direction. As can be seen from Figure 17, the intermediate layer 2 was formed on the glass substrate 1 in a thickness of approximately 30 nm (300 angstroms), and the carbon film 3 was formed on this intermediate layer 2 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 25, the intermediate layer 2 was formed so that it included a first mixture layer 23 which included SiO₂, Al₂O₃ and C was formed on the glass substrate 1 in a thickness of approximately 3 nm (30 angstroms), and a second mixture layer 24 which included Al₂O₃ and C was formed on the first mixture layer 23 in a thickness of approximately 27 nm (270 angstroms). In the first and second mixture layers 23 and 24, the mole percentages of the C became higher as outermost surfaces of the first and second mixture layers 23 and 24 approached. Also in this carbon film coated glass, the Al₂O₃ was likely to exhibit an affinity for the SiO₂ in the glass substrate 1. The contact angle of this carbon film coated glass was found to be maintained at approximately 90° even after it was worn under the same frictional conditions as those described in the First Preferred Embodiment. No change was appreciable on the carbon film 3. Modified Version In the First through Seventh Preferred Embodiments of the carbon film coated glass according to the present invention, SiO₂, TiO₂, ZrO₂, Y₂O₃, Al₂O₃ targets or evaporation sources were used to produce the intermediate layers 2. However, even when a Na₂O-CaO-SiO₂ target was used to form an intermediate layer 2, the resulting carbon film coated glass operated and effected advantages similarly to those of the First through Seventh Preferred Embodiments. Eighth Preferred Embodiment The Eighth Preferred Embodiment of the carbon film coated glass according to the present invention is adapted to be glass which has a further enhanced water repellency. As illustrated in Figure 26, this water repellent glass comprises a glass substrate 1, an intermediate layer 2 formed on the glass substrate 1, and a fluorine-including carbon film 3 in which fluorine is combined with its surface. The fluorine-including carbon film 3 includes a carbon film layer 30 formed on the intermediate layer 2, and a fluorine-including carbon film layer 31 formed on the carbon film layer 30. The other arrangements of this water repellent glass are identical with those of the First Preferred Embodiment. This water repellent glass was produced as described below. First, two targets, namely a C target and an SiO₂ target, were provided in a vacuum chamber of a bipolar RF magnetron sputtering apparatus. The glass substrate 1 was also provided in the vacuum chamber of the sputtering apparatus. The vacuum chamber was evacuated to 2 x 10⁻³ Pa or less, and the glass substrate 1 was heated to 300 °C. Then, an Ar gas was introduced into the vacuum chamber until a pressure therein became 1 x 10⁻¹ Pa, and RF electric powers (in watt) applied to the C target and the SiO₂ target were varied as time elapsed as illustrated in Figure 18, thereby carrying out film forming by sputtering. Thus, the carbon film coated glass was obtained which had the intermediate layer 2 formed on the glass substrate 1 and the carbon film layer 30 formed on the intermediate layer 2 and having a good adhesion therewith. Thereafter, a CF₄ gas was mixed in the Ar gas in an amount of 10% by volume, and a flow of the mixture gas was adjusted so that a pressure in the vacuum chamber was 1 x 10⁻¹ Pa. Then, an RF electric power of 200 W was applied to a metallic substrate holder, thereby generating a plasma adjacent to the above-described carbon film coated glass. A surface fluorination treatment was thus carried out in 10 minutes, thereby obtaining the water repellent glass illustrated in Figure 26. This water repellent glass was analyzed quantitatively with the AES apparatus for its C, Si, O and F atomic percentages from its outermost surface in a depthwise direction, and results of this quantitative analysis are shown in Figure 19. Figure 19 illustrates the relationship between etching time (in minutes) required for etching the C, Si, O and F from the surface of the water repellent glass and atomic percentages (in atomic %) of the elements. The relationship can be converted to a thickness (in nm (angstrom)) of the films and the layers. As can be seen from Figure 19, it is understood that the intermediate layer 2 was formed on the glass substrate 1 in a thickness of approximately 40 nm (400 angstroms), and that the fluorine-including carbon film 3 which included the carbon film layer 30 and the fluorine-including carbon film layer 31 was formed on this intermediate layer 2 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 27, the intermediate layer 2 was formed so that it included an SiO₂ layer 25 which included SiO₂ only was formed on the glass substrate 1 in a thickness of approximately 10 nm (100 angstroms), and a mixture layer 26 which included SiO₂ and C and in which the mole percentage of the C became higher as the outermost surface approached was formed on the SiO₂ layer 25 in a thickness of approximately 30 nm (300 angstroms). The fluorine-including carbon film layer 31 was formed by combining F with the carbon film layer 30 which included C only as described above. Accordingly, as can be seen from Figure 19, the mole percentage of the F became higher as the outermost surface approached in the fluorine-including carbon film layer 31. The contact angle of this water repellent glass was found to be 120° with respect to the water droplet. It is apparent that this water repellent glass exhibited a water repellency which is enhanced more than those of the First through Seventh Preferred Embodiments of the present carbon film coated glass. Further, a weather resistance of this water repellent glass was evaluated with a sun-shine weatherometer under a predetermined moisture condition at 63 °C. Even after the water repellent glass is exposed to the weathering conditions for 2,000 hours, it still exhibited a contact angle of approximately 100°. Thus, this water repellent glass was found to have an extremely favorable weather resistance. As for the carbon film coated glass which differed from this water repellent glass only in that it was not subjected to the previously described surface fluorination treatment, it exhibited a deteriorated contact angle of approximately 60°, after it was exposed to the weathering conditions for 1,000 hours. Furthermore, a surface of this water repellent glass was worn under the same frictional conditions as those described in the First Preferred Embodiment. It was found that the adhesion of the fluorine-including carbon film 3 which included the carbon film layer 30 and the fluorine-including carbon film layer 31 formed thereon was as excellent as those of the First through Seventh Preferred Embodiments. In addition, it is believed that this water repellent glass absorbs less light in the visible light range than the carbon film 3 of the First through Seventh Preferred Embodiments including carbon only does. This is because carbon is combined with fluorine in the fluorine-including carbon film 3 of this water repellent glass which included the carbon film layer 30 and the fluorine-including carbon film layer 31 formed thereon. Accordingly, this water repellent glass can raise the transmittance of the visible light. Hence, this water repellent glass could provide not only the superb water repellency but also the favorable weather resistance and adhesion. Moreover, it could provide a satisfactory transparency as well. Ninth Preferred Embodiment The Ninth Preferred Embodiment of the carbon film coated glass according to the present invention is also adapted to be glass which has a further enhanced water repellency. As illustrated in Figure 28, this water repellent glass includes a fluorine-including intermediate layer 27 which includes SiO₂, F and balance of C, and a fluorine-including carbon film 32. The other arrangements of this water repellent glass are identical with those of the Eighth Preferred Embodiment. This water repellent glass was produced as described below. First, in a manner similar to the Eighth Preferred Embodiment, two targets, namely a C target and an SiO₂ target, were provided in the vacuum chamber of the bipolar RF magnetron sputtering apparatus. The glass substrate 1 was also provided in the vacuum chamber of the sputtering apparatus. The vacuum chamber was evacuated to 2 x 10⁻³ Pa or less, and the glass substrate 1 was heated to 300 °C. Then, a mixture gas which included a CF₄ gas in an amount of 20% by volume and balance of an Ar gas was introduced into the vacuum chamber until a pressure therein became 1 x 10⁻¹ Pa, and RF electric powers (in watt) applied to the C target and the SiO₂ target were varied as time elapsed as illustrated in Figure 20, thereby carrying out film forming by sputtering. Thus, as illustrated in Figure 28, the water repellent glass was obtained which included the fluorine-including intermediate layer 27 formed on the glass substrate 1 and the fluorine-including carbon film 32 formed on the fluorine-including intermediate layer 27 and having a good adhesion therewith. This water repellent glass was analyzed quantitatively with the AES apparatus for its C, Si, O and F atomic percentages from its outermost surface in a depthwise direction, and results of this quantitative analysis are shown in Figure 21. As can be seen from Figure 21, it is understood that the fluorine-including intermediate layer 27 was formed on the glass substrate 1 in a thickness of approximately 40 nm (400 angstroms), and that the fluorine-including carbon film 32 was formed on this fluorine-including intermediate layer 27 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 29, the fluorine-including intermediate layer 27 was formed so that it included a fluorine-including SiO₂ layer 28 which included SiO₂ and F was formed on the glass substrate 1 in a thickness of approximately 10 nm (100 angstroms), and a mixture layer 29 which included SiO₂, F and C and in which the mole percentage of the C became higher as the outermost surface approached was formed on the fluorine-including SiO₂ layer 28 in a thickness of approximately 30 nm (300 angstroms). The fluorine-including carbon film 32 included C and F, and it had a higher mole percentage of F adjacent to the outermost surface thereof. The contact angle of this water repellent glass was also found to be 120° with respect to the water droplet. It is apparent that this water repellent glass also exhibited an excellent water repellency. Further, weather resistance of this water repellent glass was evaluated in a manner similar to that of the Eighth Preferred Embodiment. Even after the water repellent glass is exposed to the weathering conditions for 2,000 hours, it still exhibited a contact angle of approximately 100°. Thus, it was found to have an extremely favorable weather resistance. Furthermore, in this water repellent glass, the adhesion of the fluorine-including carbon film 32 was as excellent as that of the Eighth Preferred Embodiment. In addition, since this water repellent glass had the fluorine-including intermediate layer 21, it maintained to have a water repellency which resulted from the fluorine-including intermediate layer 27 even after the outermost fluorine-including carbon film 32 was caused not to be present by an excessive wear. Moreover, C is combined with F in the fluorine-including carbon film 32 and the fluorine-including intermediate layer 27. Accordingly, this water repellent glass can further raise the transmittance of the visible light when compared with that of the Eighth Preferred Embodiment. Hence, this water repellent glass could provide not only the advantageous effects similar to those of the Eighth Preferred Embodiment, but also it could keep sufficient weather resistance for a long period time and provide a further satisfactory transparency as well. Tenth Preferred Embodiment The Tenth Preferred Embodiment of the carbon film coated glass according to the present invention is also adapted to be glass which has a further enhanced water repellency. This water repellent glass was produced in a manner similar to that of the Ninth Preferred Embodiment, however, a C target and an Al₂O₃ target were provided in the vacuum chamber of the sputtering apparatus and the RF electric powers applied to the targets were varied as time elapsed in a manner different from that of the Ninth Preferred Embodiment. The other production arrangements were the same as those of the Ninth Preferred Embodiment. This water repellent glass was produced as described below. First, in a manner similar to the Ninth Preferred Embodiment, two targets, namely a C target and an Al₂O₃ target, were provided in the vacuum chamber of the bipolar RF magnetron sputtering apparatus. The glass substrate 1 was also provided in the vacuum chamber of the sputtering apparatus. The vacuum chamber was evacuated to 2 x 10⁻³ Pa or less, and the glass substrate 1 was heated to 300 °C. Then, a mixture gas which included a CF₄ gas in an amount of 20% by volume and balance of an Ar gas was introduced into the vacuum chamber until a pressure therein became 1 x 10⁻¹ Pa, and RF electric powers (in watt) applied to the C target and the Al₂O₃ target were varied as time elapsed as illustrated in Figure 22, thereby carrying out film forming by sputtering. Thus, as illustrated in Figure 28, the water repellent glass was obtained which included the fluorine-including intermediate layer 27 formed on the glass substrate 1 and the fluorine-including carbon film 32 formed on the fluorine-including intermediate layer 27 and having a good adhesion therewith. This water repellent glass was analyzed quantitatively with the AES apparatus for its C, Al, O and F atomic percentages from its outermost surface in a depthwise direction, and results of this quantitative analysis are shown in Figure 24. As can be seen from Figure 24, it is understood that the fluorine-including intermediate layer 27 was formed on the glass substrate 1 in a thickness of approximately 40 nm (400 angstroms), and that the fluorine-including carbon film 32 was formed on this fluorine-including intermediate layer 27 in a thickness of approximately 10 nm (100 angstroms). In addition, as illustrated in Figure 29, the fluorine-including intermediate layer 27 was formed so that it included a fluorine-including Al₂O₃ layer 28 which included Al₂O₃ and F was formed on the glass substrate 1 in a thickness of approximately 10 nm (100 angstroms), and a mixture layer 29 which included Al₂O₃, F and C and in which the mole percentage of the C became higher as the outermost surface approached was formed on the fluorine-including Al₂O₃ layer 28 in a thickness of approximately 30 nm (300 angstroms). The fluorine-including carbon film 32 included C and F, and it had a higher mole percentage of F adjacent to the outermost surface thereof. This water repellent glass operated and effected advantages similarly to that of the Ninth Preferred Embodiment. Hence, the operation and the advantageous effects of this water repellent glass will not be described herein. Carbon film coated glass is disclosed which includes a glass substrate, an intermediate layer formed on a surface of the glass substrate in a thickness of 5 nm (50 angstroms) or more and consisting of metallic oxide, carbon and optionally reaction products thereof, and optionally fluorine wherein the metal content defined as oxide equivalent is 5 mole % or more, and a carbon film formed on the surface of the intermediate layer in a thickness of 1 nm (10 angstroms) or more. The intermediate layer closely binds the glass substrate and the carbon film together, and thereby it inhibits the carbon film from coming off. The carbon film coated glass is thus improved in the durability. Additionally, the carbon film can include fluorine which is combined with its surface at least, and thereby it improves the repellency of the carbon film coated glass as well as the transparency thereof.

Claims: Carbon film coated glass, comprising: a glass substrate; an intermediate layer formed on a surface of said glass substrate in a thickness of 5 nm (50 angstroms) or more and consisting of metallic oxide, carbon and optionally reaction products thereof, and optionally fluorine wherein the metal content defined as oxide equivalent is 5 mole % or more; and a carbon film formed on the surface of said intermediate layer in a thickness of 1 nm (10 angstroms) or more. The carbon film coated glass according to claim 1, wherein a mole percentage of carbon increases in said intermediate layer as an outermost surface thereof approaches. The carbon film coated glass according to claim 1, wherein said intermediate layer includes a metallic oxide layer containing at least said metallic oxide, and a mixture layer formed on the metallic oxide layer and containing said metallic oxide and carbon. The carbon film coated glass according to claim 3, wherein a mole percentage of said carbon in said mixture layer increases as an outermost surface thereof approaches. The carbon film coated glass according to claim 1, wherein said intermediate layer includes a first mixture layer containing said metallic oxide, another metallic oxide and carbon, and a second mixture layer formed on the first mixture layer and containing said metallic oxide and carbon. The carbon film coated glass according to claim 5, wherein mole percentages of said carbon in said first and second mixture layers increase as outermost surfaces thereof approach. The carbon film coated glass according to Claim 1, wherein said carbon film further contains fluorine at least in a film portion thereof extending from a film surface. The carbon film coated glass according to claim 7, wherein a mole percentage of said fluorine increases in said carbon film as an outermost surface thereof approaches. The carbon film coated glass according to Claim 1, wherein said carbon film further contains fluorine through the entire film thickness. The carbon film coated glass according to claim 9, wherein a mole percentage of said fluorine increases in said carbon film as an outermost surface thereof approaches. The carbon film coated glass according to claim 1, wherein said intermediate layer further contains fluorine. The carbon film coated glass according to claim 1, wherein said glass substrate includes at least one oxide glass selected from the group consisting of silicate glass, borosilicate glass, soda-lime glass and flint glass. The carbon film coated glass according to claim 1, wherein said metallic oxide includes at least one oxide selected from the group consisting of SiO₂, TiO₂, ZrO₂, Y₂O₃, Al₂O₃, PbO, CaO, MgO, B₂O₃, Fe₂O₃, Na₂O, K₂O and Li₂O. The carbon film coated glass according to claim 7, wherein a mole percentage of carbon increases in said intermediate layer as an outermost surface thereof approaches. The carbon film coated glass according to claim 7, wherein said intermediate layer further contains fluorine. The carbon film coated glass according to claim 7, wherein said intermediate layer includes a metallic oxide layer containing at least said metallic oxide, and a mixture layer formed on the metallic oxide layer and containing said metallic oxide and carbon. The carbon film coated glass according to claim 16, wherein a mole percentage of said carbon in said mixture layer increases as an outermost surface thereof approaches. The carbon film coated glass according to claim 16, wherein said metallic oxide layer and said mixture layer further contain fluorine. The carbon film coated glass according to claim 7, wherein said intermediate layer includes a first mixture layer containing said metallic oxide, another metallic oxide and carbon, and a second mixture layer formed on the first mixture layer and containing said metallic oxide and carbon. The carbon film coated glass according to claim 19, wherein mole percentages of said carbon in said first and second mixture layers increase as outermost surfaces thereof approach. The carbon film coated glass according to claim 19, wherein said first mixture layer and said second mixture layer further contain fluorine. The carbon film coated glass according to claim 7, wherein said glass substrate includes at least one oxide glass selected from the group consisting of silicate glass, borosilicate glass, soda-lime glass and flint glass. The carbon film coated glass according to claim 7, wherein said metallic oxide includes at least one selected from the group consisting of SiO₂, TiO₂, ZrO₂, Y₂O₃, Al₂O₃, PbO, CaO, MgO, B₂O₃, Fe₂O₃, Na₂O, K₂O and Li₂O.

Inventors: NAKANISHI MASATSUGU C O TOYOTA, TSUTSUKI MISAO C O TOYOTA JIDO, YOKOISHI SHOUJI C O TOYOTA JID, NAKANISHI, MASATSUGU, C/O TOYOTA JIDOSHA K.K., TSUTSUKI, MISAO, C/O TOYOTA JIDOSHA K.K., YOKOISHI, SHOUJI, C/O TOYOTA JIDOSHA K.K.
Applicants: TOYOTA MOTOR CO LTD, TOYOTA JIDOSHA KABUSHIKI KAISHA
Application year: 1992
Main classification: C03C17
IPC codes: C03C17