MXPA01006022A - Methods and apparatus for producing silver based low emissivity coatings without the use of metal primer layers and articles produced thereby - Google Patents

Abstract

Methods are presented for depositing an infrared reflective, e.g., silver, containing multi-layer coating onto a substrate to form a coated article. One or more ceramic cathodes are used to deposit a protective layer over the silver layer. The use of the ceramic cathodes eliminates the need for the metal primer layers common in the prior art. Both the infrared reflective layer and a ceramic layer can be deposited in the same coating zone, this coating zone containing sufficient oxygen to provide a substantially oxidized ceramic coating layer without adversely impacting upon the properties of the infrared reflective layer.

Description

METHODS AND APPLIANCES FOR THE PRODUCTION OF LOW EMISSIVITY COATINGS BASED ON SILVER WITHOUT THE USE OF METALLIC PRIMER LAYERS AND ARTICLES PRODUCED IN THIS MANNER BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates generally to the field of vacuum deposition by magnetron spray and, more particularly, to the spraying of a stack of multilayer coatings having a reflective infrared metal layer without coating of primer layers. metallic, and also refers to the article manufactured in this way. 2. Description of the Available Technology Currently Sunlight contains luminous energy that generally enters into three broad regions: ultraviolet, visible and infrared. For many commercial applications, such as the windows of buildings or automobile windows, it is desirable to reduce the amount of energy, i.e., heat, transferred through the window in the interior and / or outside the building or the automobile. This reduction in heat can be affected by the reduction of light energy transmitted from any of these three regions. However, it is typically not practical to remove too much visible light energy, since this adversely impacts the ability of people to see through the window. Therefore, it is desirable to block as much of the remaining energy as possible, such as infrared energy, since this will result in the greatest reduction of transmitted energy without adversely impacting. about the transmittance of visible light. To reduce the transmittance of solar infrared energy, it is known to deposit layers of reflective infrared metal, such as silver, gold, aluminum or copper, on a glass substrate. However, if only a reflective infrared metal were applied, this would result in a mirror-like finish that would also reflect visible light. Therefore, an anti-reflective layer is usually provided on one or both sides of the infrared reflective layer to produce a substrate which is highly reflective of infrared energy, but which is also highly transmissive of visible energy. These anti-reflective layers are usually formed of a dielectric material, for example, of metal oxides, such as Zn2Sn04, Tn2Sn04, Ti02, Sn02, ln203, ZnO, Si3N4, or Bi203, to name a few. Reflective and infrared reflective layers are typically formed on the glass substrate in a sputter coating device using a technique known in the art of spraying as vacuum deposition by magnetron sputtering. The anti-reflective layer is normally deposited on the substrate by spraying a cathode of metal or metal alloy in a reactive atmosphere, for example, an oxygen rich atmosphere, to deposit a dielectric coating of metal oxide on the surface of the substrate of glass . A cathode made of an infrared reflective metal, such as silver, is sprayed in an inert, non-reactive atmosphere, for example, free of oxygen, such as argon to deposit an infrared reflective metallic layer on the anti-reflective layer. The oxygen-free atmosphere is used to deposit a metal layer and to prevent oxidation of the reflective infrared metal cathode. To prevent the decomposition of the silver layer by oxidation or agglomeration during the spraying of a subsequent anti-reflective layer, a protective metallic primer layer is deposited, such as copper, niobium, titanium, tantalum, chromium, tungsten, zinc , Indian, of nickel-chromium alloys or similar metal, on the silver layer. An example of the formation of metal primer layers of this type is described in U.S. Patent No. 5,318,685, the disclosure of which is incorporated herein by reference. These metallic primer layers are typically in the order of about 10-30 Angstroms in thickness and are sacrificial. That is to say, that the thickness of the metal primer layers is determined based on the coating parameters of the system, so that most of the metal primer layer is reactive, i.e., that it is oxidized during the spraying of the next anti-corrosion layer. -refle-xiva. The protective metallic primer layer is transparent when it is completely oxidized, so that the oxidized metal primer layer does not adversely impact the transmittance of the light and the reflective qualities of the coated substrate. However, this subsequent oxidation of the metal primer layer is not easily controlled and it is not unusual that this oxidation is incomplete. In addition, metal atoms from some metallic primer layers tend to be alloyed with the metal of the layer Reflective metallic infrared that degrades the interface between the two layers. Although generally acceptable for the production of low emissivity coated substrates, there are drawbacks associated with conventional coating methods. For example, for a coated glass to be used without further processing or thermal conditioning, if the entire metal primer layer is not oxidized during the acation of the next anti-reflective layer, the residual metal primer layer causes a decrease in transmission of visible light. Additionally, the amount and thickness of the residual metal primer layer left after the acation of the following anti-reflective layer has an effect on the physical properties of the coating, such as the hardness of the reflective substrate. Therefore, it is important to a only as much metal primer layer as will be oxidized during the spraying of the next anti-reflective layer. However, by controlling the thickness of the metal primer layer to such a degree of required security, for example, 10-30 A, significant process complexity is obtained. The safe thickness control is difficult, for example, within an atomic layer. In addition, it is difficult to control the oxidation of the metallic primer layer. In addition to the limitations resulting from incomplete oxidation of the primer layer, with conventional coating devices, valuable coating space is wasted due to the need to have metallic, reflective, infrared, oxygen-free, discrete coating zones separated from the areas of anti-reflective coating that contain oxygen. Additionally, if the coated substrate is to be heat treated additionally, such as by bending, thermal consolidation and tempering, the thickness of the metal primer layer must be increased during processing to leave a sufficient layer of residual, non-oxidized metallic primer to protect the coating. Silver layer during a subsequent thermal treatment of this type. This means that for commercial purposes, two inventories of the coated substrate should normally be maintained, one having a relatively thin, oxidized primer layer suitable for immediate use and one having a relatively thicker primer layer with a non-oxidized metal primer layer. for use after additional heat treatment. However, it is not unusual that the coating properties, such as color, transmission and clarity, are adversely influenced by the subsequent thermal treatment of conventional low-emissivity coated substrates, even with thicker primer layers. As can be appreciated by those skilled in the art, it would be advantageous to provide a coating having one or more reflective infrared metallic layers without the need for conventional metal primer layers, and a method of manufacturing them.

COMPENDIUM OF THE INVENTION A coated article, for example, a car transparency, for example, a windshield or architectural window, manufactured in accordance with invention has a substrate with an infrared reflective metallic layer, for example, a layer of silver, deposited on the substrate and a ceramic layer, for example, a layer of zinc oxide bonded with aluminum, preferably deposited from a ceramic cathode on the silver layer. Additional anti-reflective or ceramic layers can be deposited below the reflective infrared metal layer or on the ceramic layer. The invention provides a method of spraying a multilayer coating stack having an infrared reflective metal, eg, silver, onto a substrate by spraying an infrared reflective metal cathode to deposit an infrared reflective layer on the substrate and spraying then a ceramic cathode, such as a zinc oxide cathode bonded with aluminum, to deposit a ceramic, non-sacrificial layer on the silver layer. The silver layer and the ceramic layer can each be sprayed in an inert atmosphere containing a low percentage of oxygen, for example, in the same coating chamber of a coating device with the oxygen content controlled in the manner it is described up to a level to minimize unwanted effects on the silver layer. For example, the oxygen content can be adjusted to about 0-20% by volume to prevent the resistivity of the silver layer from being increased to an undesired level, for example, to be increased by an amount equal to about 75% or more than the resistivity of a silver layer of similar thickness pulverized in a non-reactive, inert atmosphere. Additional ceramic or anti-reflective layers can be deposited below the silver layer or on the ceramic layer. A coating device is also provided for spraying a multi-stack coating having an infrared reflective metal, for example, silver on a substrate. The coating device includes an infrared reflective metal cathode with at least one ceramic cathode located downstream and preferably spaced from and adjacent to the infrared reflective metal cathode. The infrared reflective metal cathode and the ceramic cathode can be located in the same coating area.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a fragmentary side view of a coating device having the side wall removed for clarity purposes and using the principles of the invention. Figure 2 is a side view of a substrate having a multilayer coating incorporating the features of the invention. Figure 3 is a graph of the deposition rate with respect to the oxygen percentage for the experiments described in Table 1. Figure 4 is an absorption chart with respect to the percentage of oxygen for the experiments described in Table 1. Figure 5 is a graph of resistance and emissivity of the sheet with respect to the oxygen percentage for the experiments described in Table 2; and Figure 6 is a graph of transmittance with respect to oxygen percentage for the experiments described in Table 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For the purposes of the following description, the terms "above", "below", "right", "left", "upper", "lower", and similar spatial indicators will refer to the invention as it is oriented in the figures. However, it should be understood that the invention may assume several alternative variations and sequences of steps, except where expressly specified otherwise. It is also understood that the specific coating device and the coating processes illustrated in the accompanying drawings, and described in the following specification are merely exemplary embodiments of the invention. Therefore, the specific dimensions and other physical characteristics related to the embodiments described herein, should not be considered as limitation. The term "ceramic" used herein generally refers to materials comprising metal and non-metallic element compounds and the term "ceramic layer" refers to a layer deposited from a "ceramic" cathode. The term "envelope" means above but not necessarily adjacent to or in contact with. To fully appreciate the coating method and the resulting coated article, it is will first describe a coating device using the features of the invention. The coating device is designated 10 in FIG. 1, and includes a first coating zone 12, a second coating zone 14 and a third coating zone 16. A conveyor 18 is configured to move a substrate 20 to be coated to through zones 12, 14, and 16 at a selected speed. The substrate can be made of any material, for example, but without limiting the invention, of plastic, clear or tinted glass, metal, glass ceramic. The zones 12, 14 are isolated from each other in a normal manner, for example, by structurally separated or interstage steps, having diffusion or turbomolecular pumps to help prevent gases from an area from diffusing into a zone. adjacent zone, as indicated by the dashed lines in Figure 1. The first zone 12 includes one or more cathode supports 24 for receiving a cathode target 26 for spraying. The third zone 16 is similar to the first zone 12 and includes one or more cathode supports 28 for receiving one or more cathode targets 30. In one embodiment of the invention, the second zone 14 has two cathode holders 34 and 36, each supporting a cathode target 38 and 40, respectively. For ease of description, reference will be made to the cathode objectives hereinafter simply as "cathodes". The cathode 38 is a conventional infrared reflective metallic cathode, such as silver, gold, etc. The other cathode 40 is a conductive ceramic cathode that incorporates characteristics of the invention, for example, a metal oxide that is conductive or is bonded to be conductive, for example, a zinc oxide cathode bonded with aluminum available from Cerac Company of Milwaukee, Wisconsin. The ceramic cathode 40 is used in place of the cathode of the metal primer layer of the prior art. The methods of spraying a stack of multilayer coatings according to the features of the invention will now be described. For purposes of the initial description, and without being considered as a limitation of the invention, the cathodes 26 and 30 in the first and third zones 12 and 16 can be conventional metal cathodes, for example, zinc cathodes and / or alloy cathodes zinc and tin of the type described in U.S. Patent No. 4,610,771, the disclosure of which is incorporated herein by reference, or zinc cathodes or silicon cathodes of the type used in the art for depositing an anti-reflective layer, for example, as described in U.S. Patent Application No. 09 / 058,440 entitled "Silicon Oxynitride Protective Coatings" filed on April 9, 1998, the disclosure of which is incorporated herein by reference. In this case, the first and third zones 12 and 16 will contain conventional reactive atmospheres, for example, rich in oxygen. The infrared reflective cathode 38 can be a silver cathode and the ceramic cathode 40 can be a zinc oxide cathode bonded with aluminum. The substrate 20, for example, a glass sheet, is moved by a conveyor 18 within the first coating zone 13 and cathode 26 is activated, for example, a cathode of zinc and tin alloy. A layer of zinc stannate is deposited on the substrate 20 in a conventional manner. The zinc stannate layer preferably has a thickness of about 20-1000 A, preferably 100-400 A, more preferably 200-350 A. The substrate 20 coated with zinc stannate is moved by the conveyor 18 within the second coating zone 14 and under the activated cathode 38. An infrared reflective layer, for example, preferably a silver layer of approximately 80-150A, is deposited on the zinc stannate layer from the zinc cathode 38 in a conventional manner. After the silver layer has been deposited, the ceramic aluminum cathode 40 bonded with aluminum is sprayed to deposit a layer of zinc oxide bonded with aluminum on the silver layer. As can be appreciated, some or all of the cathodes can be continuously activated during the deposition process or the cathodes can be activated before deposition and deactivated after deposition. As described in more detail below, the atomization atmosphere of the ceramic cathode 40 may contain oxygen, for example, 0-20% by volume. When the ceramic cathode 40 is pulverized with the plasma, the zinc, aluminum and oxygen atoms are expelled from the ceramic cathode 40 either separately or as multi-atom species. These atoms recombine on the substrate 20 to form a ceramic layer, for example, of zinc oxide bonded with aluminum on the silver layer. When used as a protective layer, the minimum amount of ceramic material applied should be that which provides uniform coverage over the silver to prevent decomposition when the next anti-reflective layer is sprayed and the maximum amount is generally limited by the economics of the coating process and it can be, for example, of the order of about 20-100 A, preferably about 30-80 A, and more preferably about 40-50 A without adversely impacting the coating properties. The method of the invention reduces or eliminates the problem of the metal-to-metal alloy associated with prior art primer layers, as previously described. Although the above description is focused on the use of aluminum oxide bonded with aluminum as the preferred ceramic material, other conductive ceramic materials can also be used which produce highly transparent layers with fractions of low oxygen content in the working gas. For example, and without being considered as a limitation of the invention, the ceramic cathode material may include tin oxide, indium oxide and / or zinc oxide with enhancers such as indium, zinc, antimony, cadmium and / or fluorine. additives to form the conductive ceramic cathodes, such as zinc stannate, antimony-tinned tin oxide, cadmium stannate, fluoride-enhanced tin oxide, tin-enhanced indium oxide, tin-enhanced indium oxide, and zinc oxide with indian In conventional spray coating processes, the reflective infrared metal layer and the metallic primer layer are deposited in an oxygen-free atmosphere to prevent the decomposition of the silver layer by oxidation. However, it has been determined that spraying a ceramic cathode containing oxygen in an oxygen-free atmosphere can result in the loss of oxygen from the pulverized ceramic material to the gas phase. This oxygen can then be pumped out by interstage diffusion pumps. Additionally, part of the oxygen from the ceramic cathode material can react with the coating material deposited on the walls or other oxygen-free surface areas of the coating device to reduce the total amount of oxygen available to form the ceramic layer. Therefore, the resulting ceramic layer, such as a layer of zinc oxide bonded with aluminum, deposited on the silver in an oxygen-free atmosphere can have a metal ratio, for example zinc and aluminum, with respect to higher oxygen than the stoichiometric. In order to calculate this oxygen loss, a small amount of oxygen can be used, for example, greater than 0 and less than 20% by volume, preferably 3-10% by volume, in the atomization atmosphere in the second zone 14. This small amount of oxygen in the atmosphere of the zone has a negligible effect on the rate of deposition and the properties of silver during spraying; however, this small amount of oxygen substantially gives rise to a completely oxidized ceramic layer, which has, for example, a substantially stoichiometric oxygen-to-metal ratio of the silver layer. The oxygen content should be regulated to prevent an increase in the resistivity of the silver layer in an amount greater than an amount equal to about 75% of the resistivity of a silver layer of similar thickness sprayed in an inert atmosphere, for example, of argon, preferably in an amount of less than about 50%, more preferably in an amount of less than about 30% and more preferably in an amount of less than about 30% and more preferably 0%, i.e., unchanged. As will be appreciated by one of ordinary skill in the art, the resistivity of the silver layer varies with the thickness of the silver layer. A description of the relationship between resistivity and film thickness is provided in the Materials Research Society Bulletin, Volume XXII, Number 9, September 1997, the disclosure of which is incorporated herein by reference. For example, for a silver layer deposited on an amorphous zinc stannate base layer, the resistivity ranges from about 10.75 μO cm to a thickness of about 60 to a resistivity of about 4.5 μO cm at a thickness of approximately 300 Á. Therefore, for example, and without being considered as a limitation of the invention, for a layer of silver 60 A thick deposited on an amorphous zinc stannate layer according to the teachings of the invention, the amount of oxygen added should preferably not lead to an increase in the resistivity of the silver layer in an amount greater than 8.1 μ cm (0.75 x 10.75 μ cm), ie a final resistivity of 18.85 μ O cm, preferably not greater than 5.4 μ cm (0.5 x 10.75 μ cm) and, more preferably not greater than 3.2 μ O cm (0.3 x 10.75 μ O cm), and more preferably without change, i.e., 0 μ O cm in the silver layer. The zinc oxide layer bonded with aluminum over the silver layer protects the silver layer during the subsequent spray deposition of the second dielectric layer in the third zone 16. Additionally, while activated, the ceramic cathode 40 acts as a sequester for the oxygen that can diffuse into the second zone 14 from the first and third zones 12 and 16, ie, that this diffused oxygen can be combined with the pulverized cathode material to help form the ceramic layer. In that respect, another ceramic cathode, the cathode 41 shown in imaginary lines in Figure 1, can be operatively placed upstream of the silver cathode 38 to sequester the oxygen on the upstream side of the silver cathode 38. After has deposited the ceramic layer, the conveyor 18 moves the substrate into the third zone 16, where a layer of zinc stannate is deposited on the ceramic layer in the conventional manner. As shown in Figure 1, additional cathodes 126 and 130 shown in imaginary lines may be present in the first and third zones 12 and 16, respectively. For example, cathodes 126 and 130 may be zinc cathodes to deposit a layer of zinc oxide on the adjacent zinc stannate layer and under the adjacent silver layer of the coating. The substrate 18 can then move into other zones similar to zones 12, 14 and 16 for the application of additional coating layers to produce, for example, a mechanically durable multilayer coated substrate structure 82 of the type shown in Figure 2. The coated substrate structure 82 has a first an i-reflective layer 84, which may include one or more different types of anti-reflective materials or one or more films of different anti-reflective materials, for example, a layer of zinc oxide on a layer of zinc stannate; a first infrared reflective metallic layer 86, for example silver; a first ceramic layer 88, for example, of zinc oxide bonded with aluminum; a second anti-reflective layer 90 which may include one or more different types of anti-re-flexing materials or one or more films of different anti-reflective materials, for example, a layer of zinc oxide on a layer of zinc stannate; a second layer of silver 92; a second layer of zinc oxide 94 bonded with aluminum; a third anti-reflective layer 96 which may include one or more different types of anti-reflective materials or one or more films of different anti-reflective materials, for example, a layer of zinc oxide on a layer of zinc stannate; and a protective overcoat 98 of the type known in the art, for example, a titanium oxide layer or a graduated silicon oxynitride layer. Reference may be made to U.S. Patent No. 5,821,001 for examples of multiple films in an anti-reflective layer and to U.S. Patent Nos. 4,716,086 and 4,786,563 for examples of protective overlays, of which Descriptions are incorporated herein by reference. The layers of zinc oxide aluminum bonded products of the present invention provide improved physical and optical characteristics and eliminate or reduce the problems associated with the metallic primer layers currently used. Since the zinc oxide layer bonded with aluminum is transparent and has a refractive index similar to conventional dielectric materials, such as zinc stannate, the thickness of the zinc oxide layer bonded with aluminum is generally not critical in the formation of transparent coatings, i.e., that the properties of the coated substrate are typically not adversely affected by the thickness of the aluminum oxide-bonded zinc oxide layer. The transmittance and reflectivity components of the coated glass substrate are not adversely affected, as would be the case with the metal protective layer of the prior art. However, the total thickness of the aluminum oxide bonded zinc layer and the adjacent anti-reflective layer must be controlled to maintain a desired optical thickness, for example, if the thickness of the zinc oxide layer is increased. With aluminum, the thickness of the adjacent anti-reflective layer should be decreased to maintain the desired optical thickness for a particular desired color. If the refractive index of the zinc oxide layer bonded with aluminum is substantially different from that of the adjacent dielectric layer, the thicknesses of these layers may need to be adjusted to maintain a desired optical thickness for a desired color. Conventional optical monitors (not shown) may be present in the coating device 10 for allow the thickness of the coating layers to be monitored and controlled. Additionally, the zinc oxide layer bonded with aluminum improves the physical properties of the coated substrate, such as hardness. Additionally, a substrate using an aluminum-bonded zinc oxide layer of the invention in place of a conventional primer layer can be further heat treated, for example, for bending, tempering or heat consolidating the coated glass substrate. Since the transmission of the ceramic primer layer of the present invention does not change significantly after heating, compared to a coating including a thick metal primer layer, a coated substrate can be used for both heated and unheated applications, eliminating the need for separate inventories of coated substrates necessary with prior art systems. As it can be appreciated, in the case that the ceramic primer layer is substoichiometric, it is foreseeable that by heating the ceramic primer layer, the composition becomes more oxidized, changing the transmittance of the ceramic primer layer and, therefore, , changing the transmittance of the coated article. Although in the process described above the cathodes 26 and 30 in the first and third zones 12 and 16, respectively, were cathodes of conventional zinc and tin alloy, one or both of these cathodes 26 and 30 could be a ceramic cathode, example of zinc oxide bonded with aluminum to replace the layers conventional anti-reflective 84, 90, with layers of zinc oxide bonded with aluminum.

Example Samples were made to study the effects of deposition of a zinc oxide layer bonded with aluminum from a ceramic cathode on a glass substrate and also on a multi-stacked coated substrate. All samples described below were performed with a conventional Aireo ILS 1600 deposition system using a system pressure of approximately 4 mTorr and power settings between 0.5-1.5 kW. The deposition parameters and deposition results of the aluminum oxide-bonded zinc layer on a glass substrate and also for the deposition for a low-emissivity coating containing silver with aluminum oxide-bonded zinc oxide primer layers on a glass substrate are shown in Tables 1 and 2, respectively. The samples indicated in Table 1 were prepared by depositing a layer of zinc oxide bonded with aluminum directly on clear floating glass substrates of twelve inches (30.48 cm) in square and 0.09 inches (2.3 mm) thickness , in a conventional manner, that is, by successively passing the substrate below the cathode during the coating. Figure 3 shows a graph of deposition rate with respect to the percentage of oxygen in the Total glass flow for the preparation of these samples. The two data sets correspond to different levels of deposition power for the Aireo ILS 1600 deposition system. Figure 4 shows the absorption of thin films of the same materials with thicknesses of approximately 500-1800 Angstroms. In pure argon, the absorption of the deposited ceramic layer is high, indicating that the layer is a very small material. However, if 5% or more oxygen is added to the spray zone or chamber, the absorption of the layer decreases sharply (Figure 4), while, in comparison, it is decrease in the deposition rate (Figure 3), it is small. What is more interesting, as shown in figures 3 and 4, the higher levels of oxygen that result in even lower deposition rates do not result in lower absorption levels, ie, that at a very high level small oxygen in the gas flow, the deposited film is essentially completely oxidized.

Table 1 Table 2 The data indicated in Table 2 are for multiple stacking coatings deposited on clear floating glass substrates of twelve inches (30.48 cm) in square and 0.09 inches (2.3 mm) in thickness. The coating stack composed of a first layer of zinc stannate deposited directly on the clear floating glass substrate; a first layer of silver deposited on the first layer of zinc stannate; a first layer of zinc oxide bonded with aluminum deposited on a ceramic cathode on the first silver layer; a second layer of zinc stannate deposited on the first layer of zinc oxide bonded with aluminum; a first layer of zinc oxide deposited on the second layer of zinc stannate; a second layer of silver deposited on the first layer of zinc oxide; a second layer of zinc oxide bonded with aluminum deposited from a ceramic cathode on the second silver layer; a second layer of zinc oxide deposited on the second layer of zinc oxide bonded with aluminum; and an overcoat of titanium oxide deposited on the second layer of zinc oxide. The shear strength, tape and clarity tests were performed on the coated substrates in a conventional manner and the results are shown in Table 2. For example, the tape test is carried out by applying a piece of Scotch brand tape. on the coating surface, pressing the tape with the hand against the coating and then pulling the tape out to visually determine if the coating has delaminated. If there is no delamination, a pass grade (P) is recorded and if it exists delamination, a degree of failure is recorded (F). The clarity test was also a visual test to qualitatively determine the amount of clarity of the coating from A + (meaning no haze) to D- (with a lot of haze). The shear strength test was carried out by traversing twenty times the substrate coated with a wet cloth followed by a visual classification of A +, which means high shear strength, at D- which means low shear strength. In Sample No. 14, of Table 2, with 30% oxygen, the coating layer was decomposed and, therefore, the mist result was not recorded. Examples of such tests are described in the aforementioned U.S. Patent No. 5,821,001. From these results, for an Aireo ILS 1600 chamber, which uses a total working gas pressure of 4 mTorr and a cathode power of 0.5-1.5 kW, the preferred region for spraying an oxide cathode of zinc bonded with aluminum, non-absorbent, appears to be between about 3-10% by volume of oxygen, preferably about 3-5% by volume of oxygen. However, as will be appreciated by one of ordinary skill in the art, this range could differ for other coating devices or for other pressures or power adjustments. As shown in Figures 5 and 6, a minimum emissivity of 0.045 can be obtained with about 3-5% by volume of oxygen. This compares favorably with the reproducible emissivity of 0.05 for coatings where the conventional titanium primer layers are used. Similarly, in this partial oxygen flow interval, observe maximum coating conductivity and transmittance. Conversely, the characteristics of the above coating are progressively degraded as the amount of oxygen in the gas increases. The optimum range of oxygen concentration corresponds to the interval where the rate of deposition of the oxidized zinc oxide with highly oxidized aluminum is very high. For the Aireo ILS 1600 system, described above, the optimum oxygen content was found to be between about 3-5% by volume. This optimal range can vary with other model systems. Preferably, as described above, the amount of oxygen should not result in an increase in the resistivity of the silver layer. With reference to Figure 5, in this system, this corresponds to an oxygen presence of 10% by volume or less. However, as also shown in Figure 5, an oxygen presence of up to 20% by volume still results in a coating with an acceptable level of emissivity. However, as described above, the maximum amount of oxygen should not be greater than that which produces an increase of approximately 30% -75% in the resistivity of the silver layer for a given thickness calculated with respect to a silver layer of similar thickness sprayed in an inert atmosphere, for example, of argon. In the case where a stable but absorbent primer layer is desired, for example, for a coated product of low emissivity and / or low matting coefficient, the ceramic cathode can be sprayed in an inert atmosphere or an atmosphere containing less than about 3% reactive gas, per example, oxygen to provide a stoichiometric ceramic primer layer that absorbs optically. As used in the description of the present invention, a stable layer is a layer that does not change chemically during normal use of the coated product having the stable layer and is expected to change when the stable layer is heated during the manufacture of the final product . In an alternative embodiment of the invention, the cathodes 26 and 30 in the first and third zones 12 and 16 can be replaced with ceramic cathodes, for example, zinc oxide bonded with aluminum. The cathode holder 36 and the cathode 40 in the second zone 14 can be removed. The amount of oxygen in the first and third zones 12 and 16 can be controlled as described above, in such a way that the ceramic layers deposited from the cathodes 26 and 30 are substantially completely oxidized. Therefore, a ceramic layer, for example, a layer of zinc oxide bonded with aluminum, can be deposited both under and over the silver layer. The additional ceramic and silver layers can be applied to form a multilayer stack. In this embodiment of the invention, the ceramic, for example zinc oxide bonded with aluminum is used not only as a protective layer for the silver layer, but also comprises all the anti-reflective layers. By reducing the number of cathode positions, the complexity of the coating device can be reduced over that required for the prior art coating devices. Although the embodiments of the Coating devices described above were continuous coating devices, the principles of the invention are applicable to other types of coating devices, such as discontinuous coating devices. Additionally, the infrared reflective and anti-reflective metals can be of any conventional type, such as those described above. Although the above description was concerned with depositing a ceramic layer on an infrared reflective metallic layer, as can be appreciated by one of ordinary skill in the art, the invention can be practiced to prevent oxidation of an underlying layer of various materials, not precisely reflective infrared metallic layers. It will be readily appreciated by those skilled in the art that modifications to the invention can be made without departing from the concepts described in the foregoing description. Such modifications should be considered included within the scope of the following claims, unless the claims, by their language, expressly indicate otherwise. Accordingly, the particular embodiments described in detail above are only illustrative and do not limit the scope of the invention which should comprise the extension of the appended claims and each and every one of its equivalents.

Claims (40)

Claims

1. A method of forming a coated article, comprising the steps of: depositing a metal layer on a substrate; and depositing a ceramic layer by spraying a ceramic cathode onto the layer to form a coated article.

2. The method according to claim 1, wherein the ceramic cathode is conductive.

3. The method according to claim 2, wherein the metallic layer is selected from the group consisting of silver, gold, aluminum and copper.

4. The method according to claim 2, wherein the ceramic layer is selected from the group consisting of tin oxide bonded with indium, zinc stannate, tin oxide bonded with antimony, cadmium stannate, tin oxide with fluoride, tin oxide indium oxide, and indium-enhanced zinc oxide.

5. The method according to claim 2, wherein the ceramic layer is a layer of metal oxide bonded with metal.

6. The method according to claim 2, wherein the ceramic layer is a layer of zinc oxide Bonded with aluminum.

7. The method according to claim 2, which includes heating the coated article to bend, temper or heat bind the coated article.

8. A coated article formed by the method of claim 1.

9. The method according to claim 2, which includes: depositing a first layer of zinc stannate on the substrate, depositing a first layer of zinc oxide on the first layer of zinc stannate, depositing the metal layer on the first layer. zinc oxide layer; depositing a second layer of zinc stannate on the ceramic layer; depositing a second layer of zinc oxide on the second layer of stannate; depositing a second layer of metal on the second layer of zinc oxide; deposit a second ceramic layer on the second metal layer; depositing a third layer of zinc stannate on the second ceramic layer; and depositing a protective overcoat on the third layer of zinc stannate.

10. The method according to claim 2, which includes: depositing a second ceramic layer on the first layer of zinc stannate; deposit the metal layer on the second ceramic layer; depositing a second layer of zinc stannate on the ceramic layer; depositing a third layer of ceramic on the second layer of zinc stannate; deposit a second layer of metal on the third ceramic layer; deposit a fourth ceramic layer on the second metal layer; depositing a third layer of zinc stannate on the fourth ceramic layer; and depositing a protective overcoat on the third layer of zinc stannate.

11. The method according to claim 2, which includes depositing an anti-reflective layer on the ceramic layer.

12. The method according to claim 2, wherein the ceramic layer is a first ceramic layer and the method includes depositing a second ceramic layer on the substrate and depositing the metal layer on the second ceramic layer.

13. The method according to claim 2, which includes depositing an anti-reflective layer on the substrate and depositing the metal layer on the anti-reflective layer. reflective

14. The method according to claim 2, wherein the step of depositing the metal layer includes depositing an infrared reflective metal layer.

15. The method according to claim 2, wherein the steps of depositing the metal layer and the ceramic layer are practiced in the same coating zone and the method further includes the step of adding sufficient oxygen to the coating zone for oxidize substantially the ceramic layer during the practice of at least one of the deposition steps.

16. The method according to claim 13, wherein the anti-reflective layer is selected from the group consisting of zinc stannate, indium tin oxide, titanium oxide, tin oxide, indium oxide, zinc oxide, silicon nitride , and bismuth oxide.

17. The method according to claim 14, wherein the metal layer is an infrared reflective metal layer and the ceramic layer is a first ceramic layer, including the method: depositing a second ceramic layer on the substrate; and depositing the infrared reflective metallic layer and the first ceramic layer on the second ceramic layer.

18. The method according to claim 14, which includes: depositing a first anti-reflective layer on the substrate, - depositing the infrared reflective layer; deposit a ceramic layer on the first anti-reflective layer; and deposit a second anti-reflective layer on the ceramic layer.

19. The method according to claim 15, which includes controlling the oxygen content in the coating zone, such that the oxygen content is approximately 0-20% by volume.

20. The method according to claim 15, wherein the metal layer is a silver layer and the method includes controlling the oxygen in the coating zone, such that the conductivity of the silver layer is not reduced below 50% of the one corresponding to a layer of silver pulverized in an argon atmosphere.

21. The method according to claim 18, wherein the steps of depositing the infrared reflective layer and depositing the ceramic layer are implemented in the same coating zone.

22. A coated article, comprising: a substrate; a metal layer deposited on the substrate; and a ceramic layer deposited by Spraying a ceramic cathode on the metal layer.

23. The coated article according to claim 22, wherein the metal layer is a reflective, infrared metallic layer.

24. The coated article according to claim 22, wherein the metallic layer is selected from the group consisting of silver, gold, aluminum and copper.

25. The coated article according to claim 22, wherein the ceramic layer is substantially completely oxidized.

26. The coated article according to claim 22, wherein the ceramic layer has a thickness of about 30-100.

27. The coated article according to claim 22, wherein the coated article is an architectural window.

28. The coated article according to claim 22, wherein the coated article is an insulating unit.

29. The coated article according to claim 22, wherein the coated article is a car glass.

30. The coated article according to claim 22, wherein the ceramic layer is selected from the group consisting of zinc oxide bonded with aluminum, zinc stannate, aluminum oxide bonded with aluminum, cadmium stannate, tin oxide with fluorine , tin oxide indium oxide and indium-enhanced zinc oxide.

31. The coated article according to claim 22, which includes: a first layer of zinc stannate deposited on the substrate; a second ceramic layer deposited on the first layer of zinc stannate, with the metallic layer deposited on the second ceramic layer; a second layer of zinc stannate deposited on the ceramic layer; a third ceramic layer deposited on the second layer of zinc stannate; a second metallic layer deposited on the third ceramic layer; a fourth ceramic layer deposited on the second metallic layer, - a third layer of zinc stannate deposited on the fourth ceramic layer; and a protective overcoat deposited on the third layer of zinc stannate;

32. The coated article according to claim 22, which includes: a first layer of zinc stannate deposited on the substrate; a first layer of zinc oxide deposited on the first layer of zinc stannate, with the metal layer deposited on the first layer of zinc oxide; a second layer of zinc stannate deposited on the ceramic layer; a second layer of zinc oxide deposited on the second layer of zinc stannate; a second metallic layer deposited on the second layer of zinc oxide - a second ceramic layer deposited on the second metallic layer; a third layer of zinc stannate deposited on the second ceramic layer; and a protective overcoat deposited on the third layer of stannate.

33. The coated article according to claim 29, wherein the automobile glass is a windshield.

34. The coated article according to claim 30, which includes another ceramic layer located between the infrared reflective layer and the substrate.

35. The coated article according to claim 32, wherein each layer of zinc stannate has a thickness of about 40-200 A, each layer of zinc oxide having a thickness of about 20-100. A, each metal layer has a thickness of approximately 80-150 A, each ceramic layer has a thickness of approximately 20-100 A, and the protective overlay has a thickness of approximately 20-50 A.

36. The coated article according to claim 32, wherein the metal layers include silver and the ceramic layers include zinc oxide bonded with aluminum.

37. The coated article according to claim 32, wherein the protective overcoat is selected from the group consisting of titanium oxide and graduated silicon oxynitride.

38. A coating device having an upstream direction and a downstream direction comprising: an infrared reflective metallic cathode; and a ceramic cathode containing oxygen located downstream of said reflective infrared metal cathode.

39. The coating device according to claim 38, including at least one other ceramic cathode located upstream of said infrared reflective metallic cathode.

40. The coating device according to claim 38, wherein said ceramic cathode is selected from the group consisting of bonded zinc oxide. ficado with aluminum, zinc stannate, tin oxide, aluminum-bonded, cadmium stannate, tin oxide with fluoride, indium oxide with tin and zinc oxide with indium.