MXPA99011013A - Article having a decorative and protective multi-layer coating - Google Patents

Abstract

An article having deposited on at least a portion of its surface a decorative and protective multi-layer coating comprising at least one nickel layer, a tin-nickel alloy layer, a chrome layer, and sandwich layer comprised of layers comprised of titanium or titanium alloy alternating with layers comprised of titanium compound such as titanium nitride or titanium alloy compound such as titanium nitride. The coating provides abrasion and corrosion protection to the underlying substrate and also protects the substrate from attack by chemicals such as acids and bases while being crack resistant and resistant to galvanic corrosion.

Description

COATING OF MULTIPLE LAYERS FIELD OF THE INVENTION This invention relates to decorative and protective coatings.

BACKGROUND OF THE INVENTION It is currently the practice with various brass items such as lamps, trivets, candlestick bars, spigots, door knobs, door handles, door lock shields and the like, burnishing and polishing first the surface of the article to a high gloss, and then apply a protective organic coating, such as one comprised of acrylics, urethanes, epoxies and the like, on this polished surface. This system has the drawback that the required operation of burnishing and polishing, particularly if the article is of a complex shape, is laborious. Also, known organic coatings are not as durable as desired and wear out.

REF .: 32091 These deficiencies are remedied by a coating having a nickel-based coating and a non-precious refractory metal compound such as zirconium nitride, titanium nitride and zirconium-titanium alloy nitride. However, it has been found that when titanium is present in the coating, for example, as titanium nitride or as zirconium-titanium alloy nitride, in corrosive environments, the coating may undergo galvanic corrosion. This galvanic corrosion makes the coating virtually useless. The presence of a tin-nickel alloy layer between the nickel base layer and the upper titanium compound or the upper titanium alloy layer has been surprisingly discovered, reduces or eliminates galvanic corrosion. A coating containing a layer of tin or nickel alloy between the nickel basecoat and the topcoat of the refractory metal compound is described in US Patent No. 5,667,904. This coating is comprised of a layer of nickel, a layer of tin-nickel alloy and a top layer comprised of the zirconium compound or titanium compound. While it is generally excellent, this type of coating has several shortcomings. This type of coating is not sufficiently resistant to attack by chemicals. This is particularly susceptible to attack by acids and bases. Another problem is that this type of coating sometimes cracks. Another deficiency is that this type of coating is subject to plastic deformation. This is due to the difference in hardness between the top layer of the non-precious refractory metal composite, and the underlying nickel and tin-nickel layers. The upper layer of non-precious refractory metal composite is harder than the underlying tin-nickel and nickel alloy layers. By applying pressure and / or force on the upper layer of the non-precious refractory metal composite, this pressure or force is transmitted through the upper layer towards the underlying tin-nickel and nickel, softer layers. The force or pressure, if large enough, causes the plastic deformation of these softer tin-nickel layers. This results in the entire coating becoming bulged, dented or deformed. The present invention remedies these deficiencies and a coating is provided that exhibits improved resistance against attack by chemicals and resistance to plastic deformation, crack resistance, and resistance to galvanic corrosion.

BRIEF DESCRIPTION OF THE INVENTION The present invention is directed to a decorative protective coating for a substrate, particularly a metallic substrate. More particularly, it is directed to a substrate, particularly a metal substrate such as brass, which has on at least a portion of its surface a coating comprised of multiple superposed layers of certain specific types of metals or metal compounds. The coating is decorative and also provides resistance against corrosion, to wear and chemicals. In one embodiment the coating provides the appearance of polished brass with a golden hue, for example, it has a golden-brass-colored hue. In this way, a surface of the article having the coating on it simulates polished brass with a golden hue. A first layer deposited directly on the surface of the substrate is comprised of nickel. The first layer can be monolithic, for example, a single nickel layer or it can consist of two different layers of nickel such as a nickel layer, bright, deposited directly on the surface of the substrate and a layer of bright nickel superimposed on the layer of semi-bright nickel. Placed on the nickel layer is a layer comprised of a tin-nickel alloy. On the tin alloy and nickel layer is a layer comprised of chromium. On the chromium layer is a sandwich layer comprised of alternating layers of titanium or titanium alloy, of a titanium compound or a titanium alloy compound. The sandwich layer is accommodated such that a layer of titanium or titanium alloy is on the chromium layer, for example, it is the bottom layer, and the layer of the titanium compound or the titanium alloy compound is the top layer or exposed. In another embodiment of the invention, placed on the layer of the titanium compound or the titanium alloy compound is a layer comprised of titanium oxide or titanium alloy oxide, a layer comprised of the reaction products of titanium or titanium. titanium alloy, oxygen and nitrogen.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view, not to scale, of the multilayer coating on a substrate; Figure 2 is a view similar to Figure 1 of a second embodiment of the present invention, having a nickel layer interposed between the nickel-tin alloy layer and the chromium layer; and Figure 3 is a view similar to Figure 1, except that the coating includes a top layer of refractory metal oxide.

DESCRIPTION OF THE PREFERRED MODALITY The substrate 12 can be any plastic, metal or metal alloy. Illustrative of metallic substrates and metallic alloy, are copper, steel, brass, tungsten, nickel alloys and the like. In one embodiment, the substrate is brass. A layer of nickel 13 is deposited on the surface of the substrate 12 by conventional and well-known electroplating processes. These processes include the use of a conventional electroplating bath such as, for example, a Watts bath as the plating solution. Typically, such baths contain nickel sulfate, nickel chloride and boric acid dissolved in water. All chloride, sulphamate and fluoroborate plating solutions can also be used. These baths may optionally include a number of well-known and conventionally used compounds such as leveling agents, brighteners and the like. To produce the specularly bright nickel layer, at least one class II polish is added to the plating solution. Class 1 polishes are organic compounds that contain sulfur. Class II polishes are organic compounds that do not contain sulfur. Class II polishes can also cause leveling, and when added to the plating bath without sulfur-containing class I brighteners, they result in n-bright deposits. These classes of brighteners I include alkyl-naphthalene- and benzenesulfonic acid. Benzene- and naphthalene-di- and tri-sulphonic acids, benzene and naphthalene-sulphonamides, and sulfonamides such as saccharine, vinyl and allyl sulfonamides and sulphonic acids. It is generally understood that class II polishes are organic materials such as for example acetylenic or ethylenic alcohols, ethoxylated and propoxylated acetylenic alcohols, coumarins and aldehydes. These class I and class II brighteners are well known to those of skill in the art and are readily available commercially. These are described, inter alia, in U.S. Patent No. 4,421,611 incorporated by reference herein.

The nickel layer 13 may be comprised of a simple nickel layer such as, for example, bright nickel, or may be comprised of two different layers of nickel, such as the semi-glossy nickel layer, and a bright nickel layer . In the figures, layer 14 is comprised of semi-glossy nickel, while layer 16 is comprised of bright nickel. This double nickel deposit provides enhanced protection against corrosion to the underlying substrate. The semi-glossy sulfur-free plate 14 is deposited by conventional electroplating processes directly onto the surface of the substrate 12. The substrate 12 containing the semi-glossy nickel layer 14 is then placed in a plating bath with bright nickel , and the bright nickel layer 16 is deposited on the semi-glossy nickel layer 14, also by conventional electroplating processes. The thickness of the nickel layer 13 is generally in the range of about 2.54 micrometers ((0.0001) (100 millionths of an inch)), preferably about 3.81 micrometers (150 millionths of an inch) to about 88.9 micrometers (3,500 millionths of an inch) ). In the modality where a double nickel layer is used, the thickness of the semi-glossy nickel layer and the bright nickel layer is an effective thickness to provide enhanced protection against corrosion. In general, the thickness of the semi-glossy nickel layer 14 is at least about 1.25 micrometers (50 millionths of an inch), preferably at least about 2.54 micrometers (10.0 millionths of an inch) and more preferably at least about 3.81 micrometers ( 150 millionths of an inch). The upper thickness limit is not generally critical and is governed by secondary considerations such as cost and appearance. In general, however, a thickness of about 38.1 micrometers (1,500 millionths of an inch), preferably about 25.4 micrometers, should not be exceeded. (1,000 millionths of an inch) and still more preferably approximately 19.05 microns (750 millionths of an inch). The shiny nigth layer 16 generally has a thickness of at least about 1.25 micrometers (50 millionths of an inch), preferably at least about 3.17 micrometers (125 millionths of an inch) and more preferably at least about 6.35 micrometers (250 millionths of an inch). inch). The upper thickness range of the bright nickel layer is not critical, and is generally controlled by considerations such as cost. In general, however, a thickness of about 63.5 micrometers (2,500 millionths of an inch), preferably at least about 50.8 micrometers (2,000 millionths of an inch) and more preferably at least about 38.1 micrometers (1,500) millionths of an inch, should not be exceeded. ). The bright nickel layer 16 also functions as a leveling layer which tends to cover or fill imperfections in the substrate. Deposited on the nickel layer 16 is a layer 20 comprised of tin-nickel alloy. More specifically, the layer 20 is comprised of a nickel-tin alloy. It has surprisingly been found that the tin-nickel alloy layer reduces or eliminates galvanic corrosion when titanium is present in the vapor deposited layers. The layer 20 is deposited on the layer 16 by conventional and well known nickel-tin alloy electroplating processes. These plating processes and baths are conventional and well known, and are described, inter alia, in US Pat. Nos. 4,033,835; 4,049,508; 3,887,444; 3,772,168 and 3,940,319, all of which are incorporated by reference herein. The tin-nickel alloy layer is preferably comprised of about 50-80 weight percent tin and about 20-50 weight percent nickel, more preferably about 65% tin and 35% nickel, which represent the composition atomic of SnNi. The plating bath contains sufficient amounts of nickel and tin to provide a tin and nickel alloy of the composition described above. A commercially available tin-nickel plating process is the Ni-ColloyRM process available from ATOTECH, and described in its Technical Information Sheet No. Nicolloy, October 30, 1994, incorporated by reference herein.

The thickness of the tin-nickel alloy layer 20 is an effective thickness to reduce or eliminate galvanic corrosion. This thickness is generally at least about 0.25 micrometers (10 millionths of an inch), preferably at least about 0.50 micrometers (20 millionths of an inch) and more preferably at least about 1.27 micrometers (50 millionths of an inch). The upper thickness range is not critical and is generally dependent on economic considerations. In general, a thickness of about 50.8 micrometers (2,000 millionths of an inch), preferably at least about 25.4 micrometers (1,000 millionths of an inch), and more preferably at least about 12.7 micrometers (500 millionths of an inch), should not be exceeded. Placed on the tin-nickel alloy layer 20 is a layer 22 comprised of chromium. The chromium layer 22 can be deposited on the layer 20 by conventional and well-known chromium electroplating techniques. These techniques, together with the various chromium plating baths are described in Brassard, "Decorative Electroplating - A Process in Transition", Metal Finishing, p. 105-108, June 1988; Zaki, "Chromium Plating", PF Directory, pp. 146-160; and in U.S. Patent Nos. 4,460,438, 4,234,396 and 4,093,522, all of which are incorporated by reference herein. Chromium plated baths are well known and commercially available. A typical chromium-plated bath contains chromic acid and its salts, and catalyst ion such as sulfate or fluoride. The catalyst ions can be provided by the sulfuric acid and its salts, and the fluorosilicic acid. The baths can be operated at a temperature of approximately 44-47 ° C (112-116 ° F). Typically, a current density of approximately 1614 amps per square meter (150 amps per square foot) to about 5 to 9 volts is used in the chromium plating. The chromium layer 22 functions as a chemical barrier layer between the non-precious refractory metal and the metal alloy layer 23, and the layer 24 of non-precious refractory metal and metal alloy compound, and the alloy layer 20 tin-nickel. The chromium layer 22 improves the chemical resistance of the coating and retards or reduces the attack on the tin-nickel alloy layer 20 by chemicals such as acids, for example, HCl, H2SO4, HN03 etc., and bases, by example, NaOH, KOH, etc. The chromium layer 22 also serves to provide structural integrity to the sandwich layer 26 or reduce or eliminate the plastic deformation of the coating. The nickel layer 13 and the tin-nickel alloy layer 20 are relatively smooth in comparison to the sandwich layer 26. Thus, an object that hits, hits or presses the layer 26 will not penetrate this relatively hard layer, but that this force will be transferred to the underlying layer 20 of relatively soft tin-nickel alloy, and to the nickel layer 13, causing the plastic deformation of these layers. The chrome layer 22 which is relatively harder than the tin-nickel layer and the nickel layer, will in general resist the plastic deformation suffered by the nickel layer 13 and the tin-nickel layer 20. The chromium layer 22 has a thickness of at least effective to provide structural integrity and reduce the plastic deformation of the coating. This thickness is at least about 5.08 x 10"micrometers (2 millionths of an inch), preferably at least about 0.127 micrometers (5 millionths of an inch), and more preferably at least about 0.203 micrometers (8 millionths of an inch). The upper thickness range is not critical and is determined by secondary considerations such as cost, however, the thickness of the chromium layer should not generally exceed approximately 1,524 microns (60 millionths of an inch), preferably at least about 1.27 microns (50 millionths of an inch) and more preferably at least about 1016 micrometers (40 millionths of an inch) In yet another embodiment, as illustrated in Figure 2, a layer of nickel 21, preferably a layer of bright nickel is deposited on the tin-nickel layer 20. This nickel layer 21 serves to improve the adhesion of the chromium layer 22 to the tin-nickel layer 20. The thickness of this nickel layer 21 is an effective thickness to improve the adhesion of the chromium layer 22 to the tin-nickel layer. In general, this thickness is at least about 6.35 x 10 ~ 3 microns (0.25 millionths of an inch), preferably at least about 1.27 x 10 ~ 2 microns (0.5 millionths of an inch) and more preferably at least about 2.54 x 10"2 micrometers (1 millionths of an inch) In general, the upper thickness range is not critical and is determined by secondary considerations such as cost, appearance, and the like, however, the thickness of the niguel layer 21 must not exceed generally about 1.27 micrometers (50 millionths of an inch), preferably at least about 0.381 micrometers (15 millionths of an inch) Placed over the chromium layer 22 is a layer of sandwich 26 comprised of layers 30 comprised of titanium or titanium alloy which is alternate with the layers 28 comprised of the titanium compound or titanium alloy compound.Such structure is illustrated in the figures, wherein the number 26 represents the sandwich layer, 28 represents a layer comprised of a titanium compound or a titanium alloy compound, and represents a layer comprised of titanium or titanium alloy. The metals that are alloyed with titanium to form the titanium alloy or the titanium alloy compound, are the non-precious refractory metals. These include zirconium, hafnium, tantalum, and tungsten. The titanium alloys generally comprise from about 10 to about 90 weight percent titanium, and from about 90 to about 10 weight percent of another non-precious refractory metal, preferably from about 20 to about 80 weight percent of titanium and from about 80 to about 20 weight percent of another refractory metal. Titanium compounds or titanium alloy compounds include oxides, nitrides, carbides and carbonitrides. In one embodiment the layers 28 are comprised of titanium-zirconium alloy nitrides and the layers 30 are comprised of titanium-zirconium alloy. In this embodiment, the titanium-zirconium alloy nitride layer has a brass-colored color with a golden hue.

The sandwich layer 26 has an effective thickness to provide resistance against abrasion, scratches and wear, and to provide the required color, for example, a brass color with a golden hue. Layer 26 generally has an average thickness of about 5.08 x 10-2 micrometers (2 millionths of an inch) to about 1016 micrometers (40 millionths of an inch), preferably of about 0.01 micrometers (4 millionths of an inch) to about 0.89 micrometers ( 35 millionths of an inch) and more preferably about 0.152 microns (6 millionths of an inch) to about 0.762 microns (30 millionths of an inch). Each of layers 28 and 30 generally has a thickness of at least about 2.54 micrometers (0.01 millionths of an inch), preferably at least about 6.35 x 10 ~ 3 micrometers (0.25 millionths of an inch), and more preferably at least about 1.27. x 2 micrometers (0.5 millionths of an inch! In general, layers 28 and 30 should not be thicker than about 0.381 micrometers (15 millionths of an inch), preferably at least about 0.254 micrometers (10 millionths of an inch), and more preferably at less about 0.127 micrometers (5 millionths of an inch) In the sandwich layer, the lower layer is layer 30, for example, the layer comprised of titanium or titanium alloy The lower layer 30 is placed on the alloy layer tin-nickel layer The upper layer of the sandwich layer is layer 28 'layer 28' is comprised of titanium compound or titanium alloy compound layer 28 'is the color layer. the color to the coating.In the case of titanium-zirconium alloy nitride, this is a brass color with a golden hue.The layer 28 'has a thickness that is at least effective to provide the required color. For example, the color brass with a golden hue. In general, the layer 28 'may have a thickness that is approximately the same as the thickness of the remainder of the sandwich layer. The layer 28 'is the thickest of the layers 28, 30 comprising the sandwich layer. In general, the layer 28 'has a thickness of at least about 5.08 x 10 ~ 2 micrometers (2 millionths of an inch), preferably at least about 0.127 micrometers (5 millionths of an inch). In general, a thickness of about 1.27 micrometers (50 millionths of an inch), preferably about 0.762 micrometers (30 millionths of an inch), should not be exceeded. One method for the formation of the sandwich layer 26 is by the use of conventional and well-known vapor deposition techniques / such as technical vapor deposition or chemical vapor deposition. Physical vapor deposition processes include cathodic deposition or sputtering and cathodic arc evaporation. In a process of the present invention, cathodic deposition or cathodic arc evaporation is used to deposit a layer 30 of titanium or titanium alloy followed by reactive cathodic deposition or reactive cathodic arc evaporation, to deposit a layer 28. of titanium alloy compound such as nitride or titanium compound such as nitride.

To form the sandwich layer 26 wherein the titanium compound and the titanium alloy compound are the nitrides, the flow velocity of the nitrogen gas is varied (pulsed) during the vapor deposition such as reactive cathodic deposition or evaporation by reactive cathodic arc, between zero (without nitrogen gas or a reduced value is introduced) to the introduction of nitrogen to a desired value to form multiple alternating layers of metal 30 and metal nitride 28 in the sandwich layer 26. The number of alternating layers of metal 30 and layers 28 of refractory metal composite in the sandwich layer 26, is an effective number to reduce or eliminate cracking. This number is generally at least about 4, preferably at least about 6, and more preferably at least about 8. In general, the number of alternating layers of refractory metal 30 and refractory metal compound 28 in the sandwich layer 26 it should not exceed about 50, preferably about 40, and more preferably about 30.

In one embodiment of the invention a layer 34 comprised of the reaction products of titanium or titanium alloy, an oxygen-containing gas such as oxygen, and nitrogen, is deposited on the sandwich layer 26. The reaction products of the metal or the metal alloy, the Oxygen and nitrogen are generally comprised of metal oxide or oxide of metal alloy and metal nitride or metal alloy nitride. Thus, for example, the reaction products of titanium, oxygen and nitrogen comprise titanium oxide and titanium nitride. These metal oxides and metal nitrides and their preparation and deposition are conventional and well known, and are described, inter alia, in U.S. Patent No. 5,367,285, the disclosure of which is incorporated by reference herein. The layer 34 can be deposited by conventional and well-known vapor deposition techniques, including reactive cathodic deposition and reactive cathodic arc evaporation. AND? Yet another embodiment of the invention instead of layer 34 which is comprised of the reaction products of a refractory metal or refractory metal alloy, oxygen and nitrogen, this is comprised of titanium oxide or titanium alloy oxide. These oxides and their preparation are conventional and well known. Layer 34 containing (i) the reaction products of the non-precious refractory metal or non-precious refractory metal alloy, oxygen and nitrogen, or (ii) non-precious refractory metal oxide or non-precious refractory metal alloy oxide , is generally very thin. This has a thickness that makes the layer 34 non-opaque, translucent or transparent, so that the layer 28 is visible through it. It has a thickness that is at least effective to provide improved resistance against chemicals. In general, this thickness is at least about 1.27 x 10 ~ 3 microns (0.05 millionths of an inch), preferably at least about 2.54 x 10"3 microns (0.1 millionths of an inch), and more preferably at least about 3.81 x 10" 3 micrometers (0.15 millionths of an inch) In general, layer 34 should not be thicker than about 0.127 micrometers (5 millionths of an inch), preferably at least about 5.08 x 10-2 micrometers (0.000002) (2 millionths of an inch, and more preferably at least about 2.54 x 10"2 micrometers (0.000001) (1 millionths of an inch) Layer 34 can be deposited by well-known and conventional vapor deposition techniques, including physical vapor deposition and chemical vapor deposition, such Such as, for example, reactive cathodic deposition and reactive cathodic arc evaporation, cathodic deposition techniques and equipment for they are described, among others, in J. Vossen and W. Kern "Thin Film Processes II", Academic Press, 1991; R. Boxman et al., "Handbook of Vacuum Are Science and Technology", Noyes Pub., 1995; and U.S. Patent Nos. 4,162,954 and 4,591,418, all of which are incorporated by reference herein. In summary, in the process of cathodic deposition, a target of refractory metal (such as titanium or zirconium) which is the cathode, and the substrate are placed in a vacuum chamber. The air in the chamber is evacuated to produce vacuum conditions in the chamber. An inert gas such as Argon is introduced into the chamber. The gas particles are ionized and are accelerated towards the target to dislodge the titanium or zirconium atoms as a coating film on the substrate. In cathodic arc evaporation, an electric arc typically of several hundred amperes is struck on the surface of a metallic cathode such as zirconium or titanium. The arc vaporizes the cathode material, which is then condensed on the substrates forming a coating. Reactive cathodic arc evaporation and reactive cathodic deposition are generally similar to ordinary cathodic deposition and cathodic arc evaporation, except that it introduces a gas into the chamber, which reacts with the target material dislodged. Thus, in the case where the titanium oxide is layer 34, the cathode is comprised of titanium, and oxygen is the reactive gas introduced into the chamber. In order that the invention can be easily understood, the following example is provided. The example is illustrative and does not limit the invention to it.

EXAMPLE 1 Brass spouts are placed in a conventional soaker bath containing standard, well-known soaps, detergents, deflocculators, and the like, which is maintained at a pH of 8.9-2.2 and at a temperature of about 63-93 °. C (145-200 ° F) for 10 minutes. The brass spouts are then placed in an ultrasonic, conventional alkaline cleaner bath. The ultrasonic cleaning bath has a pH of 8.9 -9.2, is maintained at a temperature of about 71-82 ° C (160-180 ° F), and contains conventional and well-known soaps, detergents, deflocculators and the like. After the ultrasonic cleaning, the spouts are rinsed and placed in a conventional, alkaline, electro-cleaning bath for approximately 50 seconds. The electro-cleaning bath is maintained at a temperature of about 60-82 ° C (140-180 ° F), at a pH of about 10.5-11.5, and contains standard and conventional detergents. The spouts are then rinsed and placed in a conventional acid activator bath, for approximately 20 seconds. The acid activator bath has a pH of about 2.0-3.0, is at room temperature, and contains an acid salt based on sodium fluoride. The spouts are then rinsed and placed in a plating bath with bright nickel for approximately 12 minutes. The bright nickel bath is generally a conventional bath that is maintained at a temperature of about 54-66 ° C (130-150 ° F), at a pH of about 4.0-4.8, contains NIOSH4, NiCl2, boric acid and brighteners . A bright nickel layer of an average thickness of approximately 10.16 micrometers (400 millionths of an inch) is deposited on the spouts. The bright nickel plated spouts are rinsed twice, and placed in a tin-nickel plating bath for approximately 7 minutes. The bath is maintained at a temperature of about 49-60 ° C (120-140 ° F) and at a pH of about 4.5 -5.0. The bath contains stannous chloride, nickel chloride, ammonium bifluoride, and other complex, well known and conventional wetting agents. The tin-nickel layer of an average thickness of approximately 5.08 micrometers (200 millionths of an inch) is deposited on the surface of the bright nickel layer. The spouts plated with bright nickel and tin-nickel alloy are rinsed three times and then placed in a commercially available, conventional hexavalent chromium plating bath using conventional chrome plating equipment for approximately seven minutes. The hexavalent chromium bath is a conventional and well-known bath containing approximately 242.6 g / l (32 oz / gal) of chromic acid. The bath also contains conventional and well known chrome plating additives. The bath is maintained at a temperature of about 44-47 ° C (112-116 ° F), and utilizes a mixed sulfate / fluoride catalyst. The ratio of chromic acid to sulfate of approximately 200: 1. A chrome layer of approximately 0.254 micrometers (10 millionths of an inch) is deposited on the surface of the tin-nickel and bright nickel layer.

The spouts are perfectly rinsed in deionized water and then dried. The electroplated spouts are placed in a plating vessel by cathodic arc evaporation. The container is generally a cylindrical housing containing a vacuum chamber, which is adapted to be evacuated by means of pumps. A source of argon gas is connected to the chamber, by means of an adjustable chamber, by varying the speed of the gas flow. A cylindrical cathode of zirconium-titanium alloy is mounted in the center of the chamber and connected to the negative outputs of a variable direct current power supply. The positive side of the power supply is connected to the wall of the chamber. The cathode material comprises zirconium alloy and titanium. The plated spigots are mounted on spindles, 16 of which are mounted on a ring around the outer side of the cathode. The complete ring rotates around the cathode, while each spindle also rotates around its own axis, resulting in a so-called planetary motion which provides uniform exposure to the cathode for the multiple spouts mounted around each spindle. The ring typically rotates at several rpm, while each spindle performs several revolutions per revolution of the ring. The spindles are electrically isolated from the chamber and provided with rotating contacts, so that a polarization voltage can be applied to the substrate within the coating. The vacuum chamber is evacuated to a pressure of approximately 5 x 10"3 millibars and heated to approximately 150 ° C. The electroplated spouts are then subjected to a high polarization arc plasma cleaning, in which a voltage of polarization (negative) of approximately 500 volts to the electroplated spigots, while striking an arc of approximately 500 amps and holding onto the cathode.The duration of cleaning is approximately five minutes.Argon gas is introduced at a rate sufficient to maintain a pressure of 3 x 10 ~ 2 millibars A zirconium-titanium alloy layer having an average thickness of approximately 0.1 micrometers (4 millionths of an inch) is deposited on the chromium-plated spigots for a period of three minutes. The process of cathodic arc deposition involves the application of direct current energy to the cathode to form an approximate current flow. 500 amps, introducing argon gas into the vessel to maintain the pressure in the vessel at approximately 1 x 10 ~ 2 millibars, and rotating the spouts in a planetary manner described above. After the zirconium-titanium alloy layer is deposited, the sandwich layer is applied onto the zirconium-titanium alloy layer. The nitrogen flow is introduced into the vacuum chamber periodically, while the arc discharge continues at approximately 500 amps. The flow rate of nitrogen is pulsed, for example, periodically changed from a maximum flow rate, sufficient to fully react the zirconium and titanium atoms, which reach the substrate to form the zirconium-titanium alloy nitride compound , and a minimum flow velocity equal to zero or some lower value, not sufficient to fully react with the entire zirconium-titanium alloy. The period of pulsing of the nitrogen flow is one to three minutes (30 seconds to one minute, on and then off). The total time for pulsed deposition is approximately 15 minutes, resulting in a sandwich stack with 10 layers, thickness from approximately 2.54 x 10"2 to 3.81 x 10 ~ 2 micrometers (approximately one to 1.5 millionths of an inch). material deposited in the sandwich layer is alternated between the fully reacted zirconium-titanium alloy nitride compound, and the zirconium-titanium metal alloy (or substoichiometric ZrTiN with much lower nitrogen content). sandwich layer, the nitrogen flow rate is left at its maximum value (enough to form the zirconium-titanium alloy nitride compound that it reacts completely) for a time of five to ten minutes to form a "color layer" over the top of the last sandwich. After this layer of zirconium-titanium alloy nitride is deposited, an additional flow of oxygen is introduced. x 0.1 standard liters per minute, for a time of thirty seconds to one minute, while maintaining the flow rates of nitrogen and argon at their previous values. A thin layer of mixed reaction products is formed (zirconium-titanium alloy oxynitride), with a final thickness of approximately 5.08 x 10-3 to 1.27 x 10 ~ 2 micrometers (approximately 0.2 to 0.5 millionths of an inch). Finally, the arch is extinguished at the end of this last deposition period, the vacuum chamber is ventilated and the coated substrates are removed. While certain embodiments of the invention have been described for purposes of illustration, it should be understood that various embodiments and modifications may exist within the general scope of the invention.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which the same refers.

Claims (10)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. An article comprising a substrate having on at least a portion of its surface a multilayer coating, characterized in that it comprises: at least one layer comprised of nickel; a layer comprised of alloy comprised of tin and nickel; a layer comprised of chromium; a layer comprised of titanium or titanium alloy; a sandwich layer comprised of layers comprised of a titanium compound or a titanium alloy compound, alternated with layers comprised of titanium or titanium alloy; and a layer comprised of titanium compound or titanium alloy compound.

2. The article according to claim 1, characterized in that the titanium compound is titanium nitride and the titanium alloy compound is titanium-zirconium alloy nitride.

3. The article according to claim 2, characterized in that the titanium alloy is the titanium-zirconium alloy.

4. The article according to claim 1, characterized in that a layer comprised of nickel is interposed between the layer comprised of an alloy comprised of tin and nickel, and the layer comprised of chromium.

5. The article according to claim 4, characterized in that the layer comprised of nickel is comprised of bright nickel.

6. An article comprising a substrate having on at least a portion of its surface a multilayer coating, characterized in that it comprises: a layer comprised of semi-glossy nickel; a layer comprised of bright nickel; a layer comprised of alloy comprised of tin and nickel; a layer comprised of chromium; a layer comprised of titanium or titanium alloy; a sandwich layer comprised of layers comprised of a titanium compound or a titanium alloy compound, alternated with layers comprised of titanium or titanium alloy; a layer comprised of titanium compound or titanium alloy compound.

7. The article according to claim 6, characterized in that the titanium compound is titanium nitride and the titanium alloy compound is titanium-zirconium alloy nitride.

8. The article according to claim 7, characterized in that the titanium alloy is titanium-zirconium alloy.

9. The article according to claim 6, characterized in that a layer comprised of nickel is interposed between the layer comprised of an alloy comprised of tin, and nickel, and the layer is comprised of chromium.

10. The article according to claim 9, characterized in that the layer comprised of nickel is comprised of bright nickel.