MXPA96001826A - Article that has a cover of multiple, decorative and protective layers, that simulates the bro - Google Patents

Abstract

The present invention relates to an article that is coated with a multilayer coating comprising a layer of nickel deposited on the surface of the article, a layer of tin-nickel alloy deposited on the nickel layer, a layer that provides adhesion, of refractory metal, preferably of zirconium, deposited on the layer of the tin-nickel alloy, and a refractory metal compound, preferably zirconium nitride, deposited on the layer providing adhesion of the refractory metal. The coating provides the color of the polished bronze to the article and also provides protection against abrasion and corrosion.

Description

Ref. 22455 ARTICLE THAT HAS A COVERING OF MULTIPLE, DECORATIVE AND PROTECTIVE LAYERS / THAT SIMULATES THE BRONZE FIELD OF THE INVENTION The present invention relates to substrates, in particular to bronze substrates, coated with a decorative and multi-layer protective coating.

BACKGROUND OF THE INVENTION It is a very common practice with several bronze items such as lamps, placemats, candlesticks, door knobs, door handles, shields or ornamental door plates and the like, which first smooth and polish the surface of the item until a shine is obtained intense and then apply a protective organic coating, such as one comprised of acrylics, urethanes, epoxies, and the like, on this polished surface. Although this system in general is quite satisfactory, it has the disadvantage that the operation of smoothing and polishing, particularly if the article is of a complex shape, is of an intense work. Also, known organic coatings are not always as durable as desired, particularly in external applications where articles are exposed to the elements and ultraviolet radiation. Therefore, it could be quite advantageous if the brass articles, or indeed other metal articles, could be provided with a coating which gives the article the appearance of highly polished bronze and also provides resistance against wear and corrosion protection . The present invention provides such a coating.

BRIEF DESCRIPTION OF THE INVENTION The present invention is directed to a metallic substratum having a multilayer coating. ples placed or deposited on its surface. More particularly, it is directed to a metallic substrate, particularly bronze, which has deposited on its surface multiple overlapping metallic layers of certain specific types of metals, metal compounds, or metal alloys. The coating is decorative and also provides resistance against corrosion and wear. The coating provides the appearance of highly polished bronze, that is, it has a shade of bronze color. Accordingly, a surface of the article having the coating thereon simulates a highly polished bronze surface. A first layer deposited directly on the surface of the substrate is comprised of nickel. The first layer may be monolithic or preferably the same may consist of two different nickel layers such as a layer of semi-gloss nickel deposited directly on the surface of the substrate and a layer of bright nickel superimposed on the semi-gloss nickel layer. Placed on the nickel layer is a layer comprised of tin-nickel alloy. On the tin-nickel alloy layer, there is a layer comprised of a non-precious refractory metal such as zirconium, titanium, hafnium or tantalum, preferably zirconium or titanium. A top layer comprised of a zirconium compound, a titanium compound, a hafnium compound or a tantalum compound, preferably a titanium compound or a zirconium compound such as zirconium nitride, is placed on the refractory metal layer , preferably the zirconium layer. The layers of nickel and tin-nickel alloy are applied by electroplating. Layers of the refractory metal such as zirconium and refractory metal compound such as the zirconium compound are applied by vapor deposition such as ion spray deposition. .

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a portion of the substrate having a multilayer coating deposited on its surface.

DESCRIPTION OF THE PREFERRED MODALITY The substrate 12 can be any metallic or metal alloy substrate, veneer, such as copper, steel, bronze, tungsten, nickel alloys, and the like. In a preferred embodiment the substrate is bronze. The nickel layer 13 is deposited on the surface of the substrate 12 by conventional and well known electroenvironment 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 a specularly bright nickel layer, at least one class I polish and at least one class II polish is added to the plating solution. Class I brighteners are organic compounds that contain sulfur. Class II brighteners are organic compounds which do not contain sulfur. Class II brighteners can also cause leveling or leveling and, when added to the plating bath without the sulfur-containing class I brighteners, semi-glossy nickel deposits result. These class I brighteners include alkyl naphthalene and benzene sulphonic acids, benzene and naphthalene di- and trisulphonic acids, benzene and naphthalene sulfonamides, and sulfonamides such as saccharin, vmil and allylsulfonamides and sulphonic acids. Class II polishes are generally unsaturated 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 skilled in the art and are commercially available in facilitated form. They are described, inter alia, in U.S. Pat. No. 4,421,611 incorporated herein for reference. The nickel layer may be comprised of semi-bright nickel, bright nickel, or is a double layer containing a layer comprised of semi-gloss nickel and a layer comprised of bright nickel.

The thickness of the nickel layer is generally in the range from at least about 1.27 x 10 cm (50 millionths (0.00005) of an inch), preferably at least about 3.81 x 10 -4 cm (150 millionths (0.000150)). one inch), up to approximately 0.00889 cm (3,500 millionths (0.0035) of an inch). As is well known in the art, before the nickel layer is deposited on the substrate, the substrate is subjected to activation by placing it in a conventional and well known acid bath. In a preferred embodiment, the nickel layer is a monolithic layer preferably comprised of bright nickel. In another preferred embodiment as illustrated in the Figure, the nickel layer 13 is actually comprised of two different layers of nickel 14 and 16. The layer 14 is comprised of semi-glossy nickel while the layer 16 is comprised of a bright nickel. This double nickel deposit provides enhanced protection against corrosion to the underlying substrate. The semi-bright sulfur-free plate 14 is deposited by conventional electroplating processes, directly on the surface of the substrate 12. The substrate 12 containing the layer 14 of semi-gloss nickel is then placed in a bright nickel plating bath and the The bright nickel layer 16 is deposited on the semi-gloss nickel layer 14. The thickness of the semi-glossy nickel layer and the bright nickel layer is of an effective thickness or thickness to provide improved protection against corrosion. In general, the thickness of the semi-gloss nickel layer is at least about 1.27 x 10 -4 cm (50 millon-chasms (0.00005) of an inch), preferably at least about 2.54 x 10"cm (100 millionths ( 0.0001) of one inch), and more preferably at least about 3.81 x 10 -4 cm (150 millionths (0.00015) of an inch).

The upper thickness limit in general is not critical and is governed by secondary considerations such as cost. In general, however, a thickness of approximately 0.00381 cm (1,500 millionths (0.0015) of an inch), preferably almost 2.54 x 10 ~ cm (1,000 millionths) of an inch), and more "preferably in approximately 0.001905 cm (750) form. millionths 0.00075 of an inch), it must not be exceeded. The bright nickel layer 16 in general has a thickness of at least about 1.27 x 10 -4 cm (50 millionths (0.00005) of an inch), preferably at least about 3.175 x 10 -4 cm (125 millionths (0.000125) of one inch), and more preferably at least about 6.35 x 10 -4 cm (250 millionths (0.00025) of an 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 6.35 x 10 ~ cm (2,500 millionths (0.0025) of an inch), preferably about 0.00508 cm (2,000 millionths (0.002) of an inch), and more preferably about 0.00381 cm (1,500 millionths (0.0015) of an inch), should not be exceeded. The bright nickel layer 16 also functions as a leveling or leveling layer which tends to cover or fill the imperfections in the substrate. Placed on the bright nickel layer 16 is a layer 20 comprised of a tin-nickel alloy. More specifically, the layer 20 is comprised of a nickel and tin alloy. The layer 20 is deposited on the layer 16 by conventional tin-nickel electroplating processes. These tin-nickel plating processes and baths are conventional and well known and are described, inter alia, in U.S. Pat. Nos. 4,033,835; 4,049,508; 3,887,444; 3,772,168 and 3,940,319, all of which is incorporated herein by reference. The tin-nickel alloy layer is preferably comprised of about 60-70 weight percent tin and about 30-40 weight percent nickel, more preferably in approximately 65% tin and 35% nickel form, which represents the atomic composition of SnNi. The plating bath contains sufficient amounts of nickel and tin to provide a tin-nickel alloy of the composition described above. A commercially available tin-nickel plating process is the NiColloy process available from ATOTECH, and described in its Technical Information Sheet No: NiColloy, 10/30/94, incorporated herein for reference. The thickness of the layer 20 of the tin-nickel alloy is generally at least about 2.54 x 10"cm (10 millionths (0.00001) of an inch), preferably at least about 5.08 x 10 cm (20 millionths (0.00002) of one inch), and more preferably at least about 1.27 x 10"cm (50 millionths (0.00005) of an inch). The range of the upper thickness is not critical and generally depends on economic considerations. In general, a thickness of approximately 0.00508 cm (2,000 millionths (0.002) of an inch), preferably approximately 0.00254 cm (1,000 millionths) (0.001) of an inch), and more preferably in approximately 0.00127 cm (500 millionths (0.0005) of an inch) form, should not be exceeded. Placed on the layer 20 of the tin-nickel alloy is a layer 22 comprised of a non-precious refractory metal such as hafnium, tantalum, zirconium or titanium, preferably zirconium or titanium, and more preferably zirconium. The layer 20 serves, inter alia, to improve or increase the adhesion of the layer 24 to the layer 20. The layer 22 is deposited on the layer 20 by conventional and well known techniques such as vacuum coating, vapor deposition such as ion spray, and the like. Ion spraying techniques and equipment are described, inter alia, in T. Van Vorous, "Planar Magnetron Sputtering, A New Industrial Coating Technique", Solid State Technology, December 1976, p. 62-66; U. Kapacz and S. Schulz, "Industrial Application of Decorative Coatings Principle and Advantages of the Sputter Ion Plating Process", Soc. Vac. Coat., Proc. 34 / a. Arn. Techn. Conf. , Philadelphia, E.U.A., 1991, 48-61; and U.S. Patents Nos. 4,162,954 and 4,591,418, all of which are incorporated herein by reference. Briefly, in the ion spray deposition process, the refractory metal such as the target or titanium or zirconium target, 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 accelerated to the target or target to dislodge the titanium or zirconium atoms. The target or displaced target material is then typically deposited as a coating film on the substrate. The layer 22 has a thickness which is at least effective for improving the adhesion of the layer 24 to the layer 20. In general, this thickness is at least about 6.35 x 10 -7 cm (0.25 million) • chasms (0.00000025) one inch), preferably at least about 1.27 x 10 cm (0.5 millionths (0.0000005) of an inch), and more preferably at least about 2.54 x 10 -6 cm (one millionth (0.000001) of an inch). The range of the upper thickness is not critical and generally depends on considerations such as cost. In general, however, layer 22 should not be thicker than approximately 1.27 x 10 ~ 4 cm (50 millionths) of an inch), preferably approximately 3.81 x 10 ~ cm (15 millionths (0.000015) of an inch) , and more preferably in approximate form 2.54 x 10"cm (10 millionths (0.000010) of an inch.) In a preferred embodiment of the present invention, the layer 22 is comprised of titanium or zirconium, preferably zirconium, and is deposited by plating By ion spray, reactive ion spray is generally similar to ion spray deposition except that a reactive gas which reacts with target material or displaced target is introduced into the chamber, therefore, in the case where the nitride of zirconium is the upper layer 24, the target or target is comprised of zirconium and the nitrogen gas is the reactive gas introduced into the chamber. In order to react with zirconium, the color of zirconium nitride can be made similar to that of bronze of various shades or shades. The layer 24 is comprised of a hafnium compound, a tantalum compound, a titanium compound or a zirconium compound, preferably a titanium compound or a zirconium compound, and more preferably a zirconium compound. The titanium compound is selected from titanium nitride, titanium carbide, and titanium carbonitride, with titanium nitride being preferred. The zirconium compound is selected from zirconium nitride, zirconium carbonitride, and zirconium carbide, with the zirconium nitride that is preferred. The layer 24 provides resistance against abrasion and wear and the desired color or appearance, such as, for example, polished bronze. The layer 24 is deposited on the layer 22 by any well known and conventional deposition or plating processes, such as vacuum coating, reactive ion plating, and the like. The preferred method is reactive ion spray plating. The layer 24 has a thickness at least effective to provide resistance to abrasion. In general, this thickness is at least 5.08 x 10"cm (2 millionths (0.000002) of an inch), preferably at least 1016 x 10" cm (4 millionths (0.000004) of an inch), and more preferably at least 1.524. x 10"cm (6 millionths (0.000006) of an inch.) The range of the upper thickness is generally not critical and depends on considerations such as cost, generally a thickness of approximately 7.62 x 10" cm (30 millionths) one inch), preferably approximately 6.35x10"cm (25 millionths (0.000025) of an inch), and more preferably approximately 5.08 x 10" cm (20 millionths (0.000020) of an inch), must not be exceeded . Zirconium nitride is the preferred coating material and one that most closely provides the appearance of polished bronze. In order that the invention can be understood more easily, the following example is provided. The example is illustrative and does not limit the invention to it.

EXAMPLE 1 The bronze ornamental plates or plates are placed in a conventional soaking bath, containing standard and well-known soaps, detergents, deflocculants and the like, which is maintained at a pH of 8.9 - 9.2 and a Temperature of 82.2 - 93.3 ° C (180 - 200 ° F) for 30 minutes. The shields or ornamental bronze plates are then placed for six minutes in an alkaline, ultrasonic, conventional cleaning bath. The ultrasonic cleaning bath has a pH of 8.9 - 9.2, is maintained at a temperature of about 71.11 - 82.2 ° C (160 - 180 ° F), and contains conventional and well known soaps, detergents, deflocculants and the like. After the ultrasonic cleaning, the shields or ornamental plates are rinsed and placed in an electrical, alkaline, conventional cleaning bath for approximately two minutes. The electric cleaning bath contains a submerged, insoluble steel anode, is maintained at a temperature of about 60-82.2 ° C (140-180 ° F), a pH of about 10.5-11.5, and contains standard and conventional detergents. The shields or ornamental plates are then rinsed twice and placed in a conventional acidic activator bath for about one minute. The acid activator bath has a pH of about 2.0-3.0, is at an ambient temperature, and contains an acid salt based on sodium fluoride. The shields or ornamental plates are then rinsed twice and placed in a semi-gloss nickel plating bath for about 10 minutes. The semi-gloss nickel bath is a conventional and well-known bath which has a pH of about 4.2-4.6, is maintained at a temperature of about 54.4-65.5 ° C (130-150 ° F), contains NiSO., NiCl_, acid boric, and brighteners. A layer of semi-gloss nickel of an average thickness of approximately 6.35 x 10"cm (250 millionths) of a flea-day (0.00025) is deposited on the surface of the shield or ornamental plate. Semi-gloss nickel are then rinsed twice and placed in a bright nickel plating bath for approximately 24 minutes.The bright nickel bath is generally a conventional bath which is maintained at a temperature of about 54.4-65.5 ° C (130 ° C). -150 ° F), a pH of about 4.0-4.8, contains NiS04, NiCl2, boric acid, and brightener.A bright nickel layer with an average thickness of about 0.001905 cm (750 millionths (0.00075) of an inch) , is deposited on the semi-gloss nickel layer.The bright nickel plated ornamental plates or plates are rinsed twice and placed in a tin-nickel plating bath during approximately 7 1/2 minutes. The bath is maintained at a temperature of approximately 48.88-60 ° C (120 ° -140 ° F) and a pH of about 4.5-5.0. The bath contains stannous chloride, nickel chloride, ammonium bifluoride, and other well known and conventional wetting agents and complexing agents. A layer of tin-nickel of an average thickness or thickness of approximately 5.08 x 10"cm (200 millionths (0.0002) of a flea-day) is deposited on the surface of the bright nickel layer. with a tin-nickel alloy, they are placed in an ion spray plating container.This container is a stainless steel vacuum vessel sold or marketed by Leybold AG of Germany.The container is generally a cylindrical enclosure containing a vacuum, which is adapted to be evacuated by means of pumps.A source of argon gas is connected to the chamber by an adjustable valve to vary the flow velocity of argon in the chamber.In addition, two sources of nitrogen gas are connected to each other. the chamber by an adjustable valve to vary the flow velocity of the nitrogen towards the chamber.

Two pairs of target or magnetron-type mountings are mounted in a spaced-apart relationship in the chamber and connected to the negative outputs of the C. C power supplies. variable. The targets or targets constitute the cathodes and the wall of the chamber is a common anode for the target or target cathodes. Target or target material comprises zirconium. A carrier or conveyor of the substrate, which carries or transports the substrates, i.e. the ornamental plates or shields, is already provided, for example, it can be suspended from the upper part of the chamber, and is rotated by an electric motor. variable speed to carry or transport the substrates between each pair of target or magnetron target mounts. The carrier or conveyor is conductive and electrically connected to the negative output of a power supply of C.C. variable. The veneered ornamental plates or shields are mounted on the carrier or carrier of the substrate in the ion spray plating container. The vacuum chamber is evacuated to a pressure of approximately 5 x 10"millibars and heated to approximately 400 ° C by means of a radiant heating heater.The target or target material is spray-cleaned to remove contaminants. The spray cleaning is carried out for approximately half a minute by applying a sufficient amount of energy to the cathodes to achieve a current flow of about 18 amps and introducing argon gas at the rate of approximately 200 standard cubic centimeters per minute, a pressure of approximately _3 3 x 10 millibars is maintained during spray cleaning. The shields or ornamental plates are then cleaned by an acid attack process at low pressure. The acid attack process at low pressure is carried out for approximately 5 minutes and involves the application of a C.C. negative which is increased over a period of one minute from about 1200 to about 1400 volts to shields or ornamental plates, and applying energy of C.C. to the cathodes to achieve a flow current of approximately 3.6 amps. The argon gas is introduced at a rate which is increased over a period of one minute from about 800 to about 1000 standard cubic centimeters per minute, and the pressure is maintained at about 1.1 x 10 millibars. Ornamental shields or plates are rotated between the target or magnetron mountings at a rate of one revolution per minute. The ornamental boards or plates are then subjected to an acid-attack cleaning process at elevated pressure for approximately 15 minutes. In the high pressure acid attack process, the argon gas is introduced into the vacuum chamber at a rate which is increased over a period of 10 minutes from about 500 to 650 standard cubic centimeters per minute (i.e. at the start the flow rate is 500 sccm and after ten minutes the flow rate is 650 sccm and remains at 650 sccm during the remainder of the process by acid attack at high pressure), the pressure _1 is maintained at approximately 2 x 10 millibars, and a negative potential which increases over a period of ten minutes from about 1400 to 2000 volts is applied to the shields or ornamental plates. The shields or ornamental plates are rotated between the target or magnetron target mounts at about one revolution per minute. The pressure in the container is maintained at approx-? 2 10 millibars. The shields or ornamental plates are then subjected to another cleaning process by acid attack, at low pressure, for about five minutes. During this cleaning process by at.aque with acid under low pressure, a negative potential of approximately 1400 volts is applied to the shields or ornamen-such plates, an energy of C.C. is applied to the cathodes to achieve a current flow of approximately 2.6 amps, and the argon gas is introduced into the vacuum chamber at a rate which increases over a period of five minutes from approximately 800 sccm (standard cubic centimeters per minute) ) to approximately 1000 sccm. The pressure is maintained at _2 at about 1.1 x 10 millibars and the shields or ornamental plates are rotated at about one rpm. The target or target material is again spray cleaned for approximately one minute, applying a sufficient amount of energy to the cathodes to achieve a current flow of approximately 18 amps, introducing the argon gas at a rate of approximately 150 sccm, and maintaining a pressure of approximately 3 x 10"millibars During the cleaning process, protections are interposed between the shields or ornamental plates and the target or magnetron mounts, to prevent the deposition of target or target material on the shields or Ornamental plates The protections are removed and a layer of zirconium having an average thickness of approximately 7.62 x 10 cm (3 millionths (0.000003) of a punagada), is deposited on the layer of the tin-nickel alloy of the shields or ornamental plates during a period of four minutes.This spray deposition process comprises the energy plication of C.C. to the cathodes to achieve a current flow of approximately 18 amps, introducing argon gas into the vessel at approximately 450 sccm, maintaining the pressure in the vessel at approximately 6 x 10 millibars, and rotating the shields or ornamental plates to approximately 0.7 revolutions per minute. After the zirconium layer is deposited, a layer of zirconium nitride having an average thickness or thickness of approximately 3.55 x 10"cm (14 millionths (0.000014) of an inch), is deposited on the zirconium layer by ion spray reactive for a period of 14 minutes A negative potential of approximately 200 volts DC is applied to the shields or ornamental plates while the power or DC power is applied to the cathodes to achieve a current flow of approximately 18 amps. Argon gas is introduced at a flow rate of approximately 500 sccm Nitrogen gas is introduced into the vessel from two sources.A source introduces nitrogen at a flow rate generally in a steady state of about 40 sccm.The other source is variable. The variable source is regulated to maintain a partial ionic current of 6.3 x 10 -11 amperes, with the variable flow of nitrogen that is inc remended or decreased when necessary to maintain the partial ionic current at this predetermined value. The pressure in the container is maintained at _3 approximately 7.5 x 10 mbar. The zirconium nitride shields or plates are then subjected to cooling at low pressure, where the heating is interrupted, the pressure is increased from about 1.1 x -. 10 -2 millibars to approximately 2 x 10-1 millibars, and the argon gas is introduced at a rate of 950 sccm. Although certain embodiments of the invention have been described for purposes of illustration, it is to be understood that there may be various embodiments and modifications 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 it relates.

Having described the invention as above, property is claimed as contained in the following

Claims (21)

R E I V I N D I C A C I O N S

1. An article comprising a metallic substrate having on it at least a portion of its surface a multilayer coating that simulates bronze, characterized in that it comprises: a layer comprised of semi-gloss nickel; a layer comprised of bright nickel; a layer comprised of an alloy of tin-nickel; a layer comprised of zirconium or titanium; and a top layer comprised of a zirconium or titanium compound.

2. The article according to claim 1, characterized in that the layer comprised of zirconium or titanium, is comprised of zirconium.

3. The article according to claim 2, characterized in that the layer comprised of the zirconium compound or the titanium compound is comprised of the zirconium compound.

4. The article according to claim 3, characterized in that the zirconium compound is comprised of zirconium nitride.

5. The article according to claim 1, characterized in that the metallic substrate is comprised of bronze.

6. An article, which contains or comprises a substrate having on at least a portion of its surface a multi-layered coating having a bronze color, characterized in that it comprises: a first layer comprised of semi-glossy nickel; a second layer on at least a portion of the first layer, comprised of bright nickel; a third layer on at least a portion of the second layer, comprised of the tin-nickel alloy; a fourth layer on at least a portion of the third layer comprised of zirconium; and an upper layer on at least a portion of the fourth layer comprised of a zirconium compound.

7. The article according to claim 8, characterized in that the substrate is comprised of bronze.

8. The article according to claim 7, characterized in that the upper layer is comprised of zirconium nitride.

9. An article comprising a metallic substrate having on at least a portion of its surface, a multiple layer coating that simulates bronze, characterized in that it comprises: a layer comprised of nickel; a layer comprised of a tin-nickel alloy; a layer comprised of zirconium or titanium; and a top layer comprised of a zirconium compound or a titanium compound.

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

11. The article according to claim 10, characterized in that the layer comprised of zirconium or titanium, is comprised of. zirconium.

12. The article according to claim 11, characterized in that the layer comprised of the zirconium compound or the titanium compound is comprised of the zirconium compound.

13. The article according to claim 12, characterized in that the zirconium compound is comprised of zirconium nitride.

14. The article according to claim 13, characterized in that the metallic substrate is comprised of bronze.

15. The article according to claim 9, characterized in that the metallic substrate is comprised of bronze.

16. An article comprising a substrate having on at least a portion of its surface a multi-layered coating having the color of bronze, characterized in that it comprises: a first layer comprised of nickel; a second layer on at least a portion of the first layer, comprised of the tin-nickel alloy; a third layer on at least a portion of the second layer, comprised of zirconium; and a top layer on at least a portion of the third layer, comprised of a zirconium compound.

17. The article according to claim 16, characterized in that the first layer is comprised of bright nickel.

18. The article according to claim 16, characterized in that the upper layer is comprised of zirconium nitride.

19. The article according to claim 17, characterized in that the upper layer is comprised of zirconium nitride.

20. The article according to claim 16, characterized in that the substrate is comprised of bronze.

21. The article according to claim 19, characterized in that the substrate is comprised of bronze.