MXPA97000185A - Substrate with a protective coating on elmi - 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 palladium deposited on the nickel layer, a layer of ruthenium deposited on the palladium layer , a layer of refractory metal, preferably zirconium, deposited on the ruthenium layer, and a refractory metal compound, preferably of zirconium nitride, deposited on the refractory metal layer. The coating provides the color of the polished bronze to the article and also provides protection against abrasion and corrosion.

Description

SUBSTRATE WITH A PROTECTIVE COVERAGE ON THE SAME Field of the Invention The present invention relates to metal substrates such as bronze or brass coated with a multi-layer, protective metal coating.

Background of the Invention It is a common practice with various brass or brass items such as lamps, table mats, candle holders, knobs and door handles and the like, first burnishing and polishing the surface of the item until an intense shine is obtained and then applying 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 completely satisfactory, it has the disadvantage that the burnishing and polishing operation, particularly if the article is of a complex shape, is intense in terms of the work performed. 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.

Ref. 23836 Therefore, it could be completely advantageous if brass or brass articles, or indeed other metal articles, could be provided with a coating which gives the article the appearance of highly polished brass or brass and also provides it with resistance to wear and protection against corrosion. The present invention provides such a coating.

Brief Description of the Invention The present invention is directed to a metal substrate having a multilayer coating placed or deposited on its surface. More particularly, it is directed to a metallic substrate, particularly bronze or brass, which has deposited on its surface multiple overlapping metallic layers of certain specific types of metals or metal compounds. The coating is decorative and also provides resistance against corrosion and wear. The coating simulates the appearance of highly polished brass or brass, that is, it has a color tone of bronze or brass. Accordingly, a surface of the article having the coating thereon simulates a highly polished brass or brass surface. A first layer deposited directly on the surface of the substrate is comprised of nickel. Placed on the nickel layer is a layer comprised of palladium. This layer of palladium is thinner than the nickel layer. On the palladium layer is a layer comprised of ruthenium. On the ruthenium layer 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 or titanium nitride, is placed on the refractory metal layer, preferably the zirconium layer. The nickel, palladium and ruthenium layers are applied by electroplating. The refractory metal layer such as the zirconium layer and the refractory metal composite layer such as the zirconium compound layer 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 the multilayer coating deposited on its surface.

Description of the Preferred Modality The substrate 12 can be any metal or metal alloy substrate such as copper, steel, bronze, tungsten, nickel alloys, and the like. In a preferred embodiment, the substrate is brass or brass. The nickel layer 13 is deposited on the surface of the substrate 12 by conventional and well-known plating processes. These processes include electroplating processes using conventional and well-known electroplating baths 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 or to obtain homogeneous and uniform deposition, 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 which contain sulfur. Class II brighteners are organic compounds which do not contain sulfur. Class II brighteners can also cause homogeneous and uniform deposition and, when added to the plating bath without sulfur-containing class I brighteners, lead to semi-glossy nickel deposits. 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 saccharine, vinyl and allyl sulfonamides 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 readily available in the trade. They are described, inter alia, in U.S. Pat. No. 4,421,611 incorporated herein for reference. The nickel layer is preferably comprised of semi-bright nickel or bright nickel, more preferably bright nickel. The thickness of the nickel layer is of a thickness which is effective to provide improved corrosion protection to the underlying substrate. In general, this average thickness is from at least about 0.0001 inches (0.0001 inches), preferably at least about 0.00015 inches (0.00015 inches), and more preferably at least about 0.0002 inches (0.0002 inches). The upper thickness limit in general is not critical and is governed by secondary considerations such as cost, appearance, and the like. In general, however, an average thickness of approximately 0.00889 cm (0.0035 inches), preferably approximately 0.0076 cm (0.003 inches), and more preferably almost 0.00635 cm (0.0025 inches) should not be exceeded. As is well known in the art, before the nickel layer is deposited on the substrate, the substrate is subjected to activation by being placed in a conventional and well known acid bath. In a more preferred embodiment the nickel layer 13 is comprised of two different layers of nickel 14 and 16. The layer 14 is comprised of bright nickel. The bright plate 13 is deposited by conventional electroplating processes directly on the surface of the substrate 12. Placed on the nickel, preferably the bright nickel layer 13 is a relatively thin layer comprised of palladium. The palladium fixing layer 18 can be deposited on the nickel layer 13 by conventional and well-known palladium electroplating techniques. Accordingly, for example, the anode may be an inert platinized titanium while the cathode is the substrate 12 having the nickel layer 13 thereon. Palladium is present in the bath as a palladium salt or complex ion. Some of the complexing agents include the polyamines such as those described in U.S. Pat. No. 4,486,274 incorporated herein for reference. Some other palladium complexes such as the palladium tetra-amine complex used as the source of palladium in a number of palladium electroplating processes are described in U.S. Pat. Nos. 4, 622,110; 4,552,628; and 4,628,165; all of which are incorporated herein for reference. Some palladium electroplating processes are described in U.S. Pat. Nos. 4,487,665; 4,491,507 and 4,545,869, incorporated herein by reference. The palladium layer 18 generally has an average thickness of at least about 0.000000635 cui (0.00000025 inches), preferably at least about 0.00000127 cm (0.0000005 inches), and more preferably at least about 0.00000254 cm (0.000001 inches). In general, the upper thickness range is not critical and is determined by secondary considerations such as cost. However, the thickness of the palladium-binding layer in general should not exceed about 0.0000127 cm (0.00005 inches), preferably 0.0000381 cm (0.000015 inches), and more preferably 0.0000254 cm (0.000010 inches). The ruthenium layer 20 is deposited on the palladium layer 18 in a variety of well-known and conventional ways such as for example plating, ion spraying, vacuum deposition, and depositing the ruthenium metal as a finely divided dispersion in an organic carrier. . The ruthenium is preferably deposited by plating, preferably electroplating. The ruthenium electroplating processes and the plating baths are conventional and well known. They are described, for example, in the Journal of the Chemical Society of London, 1971 edition, page 839, by C.D. Burke and J.0. 0'Meardi and Electrodeposition of Alloys, Vol. II, pp. 4-29, Abner Brenner (1963). Ruthenium electroplating baths can be acidic or non-acidic. Some illustrative examples of non-acid ruthenium electroplating baths are described in U.S. Pat. Nos. 4,297,178 and 4,507,183, both of which are incorporated herein by reference. Some illustrative examples of the acid ruthenium plating baths are described in U.S. Pat. No. 3,793,162, incorporated herein by reference. Some other ruthenium plating baths are described in U.S. Pat. Nos. 3,576,724 and 4,377,448, both of which are incorporated herein by reference. Ruthenium plating baths include baths with a nitrous salt and sulfamate baths. Ruthenium can be electroplated through the use of continuous direct current densities or by the use of impulse current plating, that is, where a current is generated during a first period of time and is absent for a second period of time , the first and the second period of time reoccur cyclically. Ruthenium plating with a pulse current is described, for example, in U.S. Pat. No. 4,082,622, incorporated herein by reference. The average thickness of the ruthenium layer 20 is at least about 0.000005 cm (0.000002 inches), preferably at least about 0.0000127 cm (0.000005 inches), and more preferably at least about 0.0000203 cm (0.000008 inches). The higher thickness inter-val is not critical and generally depends on economic considerations. In general, an average thickness of about 0.000254 cm (0.0001 inches), preferably about 0.0001905 cm (0.000075 inches), and more preferably about 0.000127 cm (0.00005 inches) should not be exceeded. Placed on the ruthenium layer 20 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 increase or improve the adhesion of the layer 24 to the layer 20. The layer 22 is deposited on the ruthenium layer 20 by conventional and well-known techniques such as vacuum coating, physical vapor such as by ionic pulverization, and the like. The techniques and equipment for ion spray deposition are described, inter alia, in T. Van Vorous, "Planar Magnetron Sputtering"; A New Industrial Coating Technique ", Solid State Technology, Dec. 1976, pp. 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, USA, 1991, 48-61; and US Patent 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 are accelerated to the target or target to dislodge the titanium or zirconium atoms. target material or evicted target is then deposited t picamente 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 0.000000635 cm (0.00000025 inches), preferably at least about 0.00000127 cm (0.0000005 inches), and more preferably at least approximately 0.00000254 cm (0.000001 inches). 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 about 0.000127 cm (0.00005 inches), preferably about 0.0000381 cm (0.000015 inches), and more preferably about 0.0000254 cm (0.000010 inches). In a preferred embodiment of the present invention, layer 22 is comprised of titanium or zirconium, preferably zirconium, and is deposited by ion spray plating. 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 carbonate, with the titanium nitride being preferred. The zirconium compound is selected from zirconium nitride, zirconium carbonitride, and zirconium carbide, with the zirconium nitride which is preferred. The layer 24 provides resistance against wear and abrasion and the desired appearance or color, such as, for example, polished bronze. The layer 24 is deposited on the layer 22 by any of the well known and conventional plating or deposition processes such as vacuum coating, reactive ion plating, and the like. The preferred method is reactive ion spray plating. Reactive ion spray is generally similar to ion spray deposition except that a reactive gas which reacts with the target material dislodged is introduced into the chamber. Accordingly, in the case where the zirconium nitride is the top layer 24, the target or target is comprised of zirconium and the nitrogen gas is the reactive gas introduced into the chamber. By controlling the amount of nitrogen available to react with zirconium, the color of zirconium nitride can be made to be similar to that of bronze of various shades or shades. The layer 24 has a thickness at least effective to provide resistance against abrasion. In general, this thickness is at least 0.000005 cm (0.000002 inches), preferably at least 0.000010 cm (0.000004 inches), and more preferably at least 0.0000152 cm (0.000006 inches). The range of the upper thickness in general is not critical and depends on considerations such as cost. In general, a thickness of approximately 0.0000762 cm (0.00003 inches), preferably approximately 0.0000635 cm (0.000025 inch), and more preferably approximately 0.0000508 cm (0.000020 inch) should not be exceeded. Zirconium nitride is the preferred coating material because it is the 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 door plates or shields are placed in a conventional, removable cleaning bath containing the well-known and standard soaps, detergents, deflocculants and the like, which is maintained at a pH of 8.9 - 9.2 and a Temperature of 82.22-93.33 ° C (180-200 ° F) for 30 minutes. The plates or brass shields are then placed for six minutes in a conventional ultrasonic alkaline cleaner bath. The ultrasonic cleaning bath has a pH of 8.9 9.2, is maintained at a temperature of about 71.11-82.22 ° C (160-180 ° F), and contains the well-known and conventional soaps, detergents, deflocculants and the like. After the ultrasonic cleaning the plates or shields are rinsed and placed in a conventional alkaline electrolytic bath for approximately two minutes. The electro-cleaning bath contains an insoluble submerged steel anode, is maintained at a temperature of about 60-82.22 ° C (140-180 ° F), a pH of about 10.5-11.5, and contains standard and conventional detergents. The plates or shields are then rinsed twice and placed in a conventional acid 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 plates or shields are then rinsed twice and placed in a bright nickel plating bath for approximately 24 minutes. The bright nickel bath in general is a conventional bath which is maintained at a temperature of about 54.44-65.55 ° C (130-150 ° F), a pH of about 4.0-4.8, contains NiSO ,, NiCl ~. boric acid, and brighteners. A bright nickel layer with an average thickness of approximately 0.001905 cm (0.00075 inches) is deposited on the semi-gloss nickel layer. Shiny nickel-plated plates or shields are rinsed three times and placed for approximately one and a half minutes in a conventional palladium plating bath. The palladium bath uses an insoluble platinized niobium anode, is maintained at a temperature of about 35-60 ° C (95-140 ° F), a pH of about 3.7-4.5, contains from about 1-5 grams per liter of palladium (as metal), and approximately 50-100 grams per liter of sodium chloride. A layer of palladium of an average thickness of approximately 0.0000076 cm (0.000003 inches) is deposited on the bright nickel layer. The plates or shields plated with palladium are then rinsed twice. The palladium plated plates or shields are then placed in a conventional ruthenium plating bath for about ten minutes. The ruthenium bath uses insoluble platinized titanium anodes, is maintained at a temperature of about 65.55-76.66 ° C (150-170 ° F), a pH of about 1.0-2.0, and contains about 3 grams per liter of ruthenium. A layer of ruthenium with an average thickness of approximately 0.0000254 cm (0.000010 inches) is deposited on the palladium layer. The plates or shields are then rinsed abundantly and dried. Ruthenium-plated plates or shields are placed in a plating container by sputtering. This container is a stainless steel vacuum vessel sold or marketed by Leybold A.G. from Germany. The container is generally a cylindrical enclosure 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 an adjustable valve to vary the flow velocity of the argon towards the chamber. In addition, two sources of nitrogen gas are connected to the chamber by an adjustable valve to vary the flow velocity of nitrogen to the chamber. Two pairs of magnetron target or target mounts are mounted in a spaced relationship far into the chamber and connected to the negative outputs of the C.C. variable. The targets or targets constitute the cathodes and the wall of the chamber is a common anode for the target or target cathodes.

The target or target material comprises zirconium. A carrier of the substrate which carries the substrates, i.e. the plates or shields, is provided, for example, it can be suspended from the top of the chamber, and is rotated by a variable speed motor to carry the substrates between each pair of target mounts or magnetron target. The carrier is conductive and is electrically connected to the negative output of a power supply of C.C. variable. Ruthenium-plated plates or shields are mounted on the substrate carrier in the ion spray plating container. The vacuum chamber -3 is evacuated to a pressure of approximately 5x10 milli-baria and is heated to approximately 204.44 ° C (400 ° C) by means of a radiant electric resistance heater. The target or target material is cleaned by ion spray to remove contaminants from its surface. The ion spray cleaning is carried out for about half a minute by applying enough 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 x 10 millibars is maintained during spray cleaning.

The plates or shields are then cleaned by an acid attack process at low pressure. The acid attack process at low pressure is carried out for approximately five minutes and involves applying a potential of C.C. negative which increases over a period of one minute from about 1200 to about 1400 volts to the plates or shields 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 -2 1.1x10 milliaries. The plates or shields are rotated between the target or magnetron mountings at a rate of one revolution per minute. The plates or shields are then subjected to a cleaning process with acid at high 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 increases over a period of 10 minutes from about 500 to 650 standard cubic centimeters per minute (ie, at the start) the flow rate is 500 sccm and after ten minutes the flow velocity is 650 sccm and remains at 650 sccm for the remainder of the acid attack process at high pressure), the pressure is maintained at approximately 2x10 millibar, and a negative potential which increases over a period of ten minutes from approximately 1400 to 2000 volts is applied to the plates or shields. The plates or shields are rotated between the target or magnetron target mounts at about one revolution per minute. The pressure in the container is maintained at approximately 2x10 millibar. The plates or shields are then subjected to another cleaning process by acid attack at low pressure for approximately five minutes. During this cleaning process by acid attack at low pressure, a negative potential of approximately 1400 volts is applied to the plates or shields, the 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) up to approximately 1000 sccm. The pressure is maintained -2 at about 1.1x10 millibar and the plates or shields are rotated at about one rpm. The target or target material is cleaned by ion spray again for approximately one minute by applying enough energy to the cathodes to achieve a flow of about 18 amps., introducing argon gas at a speed of approximately 150 sccm, and maintaining a pressure of approximately 3 to 10 millibar. During the cleaning process, defenses or protections are interposed between the plates or shields and the target or magnetron mounts to prevent the deposition of target material on the plates or shields. The defenses or protections are removed and a zirconium layer having an average thickness of approximately 0.0000076 cm (0.000003 inches) is deposited on the ruthenium layer of the plates or shields for a period of four minutes. This ion spray deposition process comprises applying the energy of C.C. to the cathodes to achieve a current flow of approximately 18 amps, introduce argon gas into the vessel at approximately 450 sccm, maintain the pressure in the receiver at approximately 6x10 millibar, and spin plates or shields at approximately 0.7. revolutions per minute. After the zirconium layer is deposited, a layer of zirconium nitride having an average thickness of about 0.0000355 cm (0.000014 inches) is deposited on the zirconium layer by reactive ion spray for a period of 14 minutes. A negative potential of approximately 200 volts of C.C. it is applied to plates or shields while the energy of C.C. It is applied to the cathodes to achieve a current flow of approximately 18 amps. The 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 generally steady flow rate of about 40 sccm. The other source is variable. The variable source is regulated to maintain a partial ionic current of 6.3x10 amperes, with the variable flow of nitrogen being increased or reduced when necessary to maintain the partial ionic current at this predetermined value. The pressure in the container is maintained in approximately 7.5x10 millibar. The plates or shields coated with zirconium nitride are then subjected to a downward cooling at low pressure, where the heating is discontinued, the pressure is increased from about -2 -1 1.1x10 millibar until approximately 2x10 millibar, and the argon gas is introduced at a speed of 950 sccm. Although the present invention has been described - l i¬ in conjunction with a preferred embodiment, it is to be understood that modifications and variations can be used as a resource without departing from the spirit and scope of the invention as will be readily understood by those skilled in the art. Such modifications and variations are considered to be within the scope and scope of the invention and the appended claims.

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 (42)

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

1. An article comprising a metallic substrate having deposited on at least a portion of its surface a multilayer coating that simulates bronze or brass, characterized in that it comprises: at least one layer comprised of nickel on at least a portion of the surface of the substrate; a layer comprised of palladium on at least a portion of the layer comprised of nickel; a layer comprised of ruthenium on at least a portion of the layer comprised of palladium; a layer comprised of zirconium or titanium on at least a portion of the layer comprised of ruthenium; and a layer comprised of a zirconium compound or a titanium compound on at least a portion of the zirconium or titanium layer.

2. The article according to claim 1, characterized in that the layer comprised of nickel is comprised of bright nickel.

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

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

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

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

7. The article according to claim 6, characterized in that the layer comprised of the zirconium compound or the titanium compound, is comprised of the zirconium compound.

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

9. The article according to claim 8, characterized in that the metallic substrate is comprised of brass or brass.

10. The article according to claim 1, characterized in that the metallic substrate is comprised of brass or brass.

11. An article, comprising a substrate having on at least a portion of its surface a coating that simulates bronze or brass, characterized in that it comprises a first layer comprised of nickel; a second layer on at least a portion of the second layer comprised of palladium; a third layer on at least a portion of the second layer comprised of ruthenium; a fourth layer on at least a portion of the third layer comprised of zirconium or titanium; and a fifth layer on at least a portion of the fourth layer comprised of a zirconium compound or a titanium compound.

12. The article according to claim 11, characterized in that the substrate is comprised of brass or brass.

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

14. The article according to claim 13, characterized in that the fourth layer is comprised of zirconium.

15. The article according to claim 14, characterized in that the fifth layer is comprised of the zirconium compound.

16. The article according to claim 15, characterized in that the fifth layer is comprised of zirconium nitride.

17. The article according to claim 16, characterized in that the substrate is brass or brass.

18. The article according to claim 11, characterized in that the fourth layer is comprised of zirconium.

19. The article according to claim 18, characterized in that the fifth layer is comprised of a zirconium compound.

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

21. An article comprising a metal substrate having on it at least a portion of its surface a multilayer coating, characterized in that it comprises: a layer comprised of nickel, a layer comprised of palladium; a layer comprised of ruthenium; a layer comprised of zirconium or titanium; and a layer comprised of a zirconium compound or a titanium compound.

22. The article according to claim 21, characterized in that the layer comprised of nickel is comprised of bright nickel.

23. The article according to claim 22, characterized in that the layer comprised of zirconium or titanium is comprised of zirconium.

24. The article according to claim 23, characterized in that the layer comprised of the zirconium compound or the titanium compound is comprised of the zirconium compound.

25. The article according to claim 24, characterized in that the zirconium compound is comprised of zirconium nitride.

26. The article according to claim 25, characterized in that the metallic substrate is comprised of brass or brass.

27. The article according to claim 21, characterized in that the substrate is comprised of brass or brass.

28. The article according to claim 21, characterized in that the layer comprised of zirconium or titanium is comprised of zirconium.

29. The article according to claim 28, characterized in that the layer comprised of the zirconium compound or the titanium compound is comprised of the zirconium compound.

30. The article according to claim 29, characterized in that the zirconium compound is comprised of zirconium nitride.

31. The article according to claim 30, characterized in that the metallic substrate is comprised of brass or brass.

32. An article comprising a substrate having on at least a portion of its surface a multilayer coating, 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 palladium; a third layer on at least a portion of the second layer comprised of ruthenium; a fourth layer on at least a portion of the third layer comprised of zirconium or titanium; and a fifth layer on at least a portion of the fourth layer comprised of a zirconium compound or a titanium compound.

33. The article according to claim 32, characterized in that the first layer is comprised of bright nickel.

34. The article according to claim 32, characterized in that the fourth layer is comprised of zirconium.

35. The article according to claim 34, characterized in that the fifth layer is comprised of a zirconium compound.

36. The article according to claim 35, characterized in that the zirconium compound is zirconium nitride.

37. The article according to claim 36, characterized in that the substrate is comprised of brass or brass.

38. The article according to claim 32, characterized in that the fourth layer is comprised of zirconium.

39. The article according to claim 38, characterized in that the fifth layer is comprised of the zirconium compound.

40. The article according to claim 39, characterized in that the zirconium compound is zirconium nitride.

41. The article according to claim 40, characterized in that the substrate is comprised of brass or brass.

42. The article according to claim 32, characterized in that the substrate is comprised of brass or brass.