MXPA96001822A - Article that has a decorative and protective cover 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, and refractory metal compound , preferably zirconium nitride, deposited on the tin-nickel layer. The coating provides the color of the polished bronze to the article and also provides protection against abrasion and corrosion.

Description

Ref. 22452 ARTICLE THAT HAS A OBOGRATIVE RECOGNITION ¥ HtOTECTOR THAT SIMULATES THE BRONZE ^ FIELD OF THE INVENTION The present invention relates to substrates, in particular to bronze substrates, coated with. a protective and decorative coating of multiple layers.

BACKGROUND OF THE INVENTION It is very common in practice with various bronze items such as lamps, table mats, candlesticks, door knobs, door handles, scutes or ornamental door plates and the like, which is first smoothed and polished the surface of the to achieve an intense gloss 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 very satisfactory, it has the disadvantage that the smoothing and polishing operation, 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 outdoor applications where articles are exposed to the elements and ultraviolet radiation. Therefore, it could be very advantageous if brass articles, or indeed other metal articles, could be provided with a coating which gives the article the appearance of polished brass and which also provides wear resistance and protection against corrosion. The present invention provides such a covering.

BRIEF DESCRIPTION OF THE INVENTION The present invention is directed to a metal substrate having a multi-foot layer coating placed or deposited on its surface. More particularly, it is directed to a metal substrate, particularly bronze, 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 provides the appearance of polished bronze, that is, a color tone of bronze. Thus, a surface of the article having the coating on it, simulates a polished bronze surface. A first layer deposited directly on the surface of the substrate is comprised of nickel. The first layer is preferably comprised of a layer of bright nickel. Deposited on the nickel layer is a layer comprised of a tin-nickel alloy. On the layer of the tin-nickel alloy is a top layer comprised of a non-precious or inexpensive refractory metal compound such as a zirconium gate, a titanium compound, a hafnium compound or a tantalum compound, preferably a compound of titanium or a zirconium compound such as zirconium nitride. The nickel and tin-nickel alloy layers are applied by electroplating. The refractory metal compound such as the zirconium compound layer is applied by vapor deposition such as reactive ion spray deposition.

BRIEF DESCRIPTION OF THE DRAWING 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, venerable substrate, 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 are 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. These brighteners of citase I include alkyl naphthalene and benzene sulphonic acids, benzene and naphthalene di- and trisulfonic acids, benzene and naphthalene sulfonamides, and sulfonamides such as saccharin, 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 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 is comprised of bright nickel. The thickness or thickness of the nickel layer is generally in the range from at least about 1.27 x 10 -4 cm (50 millionths (0.00005) of an inch) to about 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 acid activation by being placed in a conventional and well known acid bath.

The thickness or thickness of the nickel layer is of an effective thickness to provide "" enhanced protection against corrosion. In general, the thickness of the bright nickel layer 13 is at least about 1.27 x 10 cm (50 millionths (0.00005) of an inch), preferably at least about 2.54 x 10 ~ cm (100 millionths (0.0001) ) of one inch), and more preferably of at least about -4 3.81 x 10 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. Generally, however, a thickness of about 0.00889 cm (3,500 millionths (0.0035) of an inch), preferably approximately 0.00508 cm (2,000 millionths (0.002) of an inch), and more preferably about 0.0038 cm ( 1,500 millionths (0.0015) of an inch), should not be exceeded. Placed on the bright nickel layer 13 is a layer 20 comprised of a tin-nickel alloy. More specifically, the layer 20 is comprised of a nickel-tin alloy. The layer 20 is deposited on the layer 13 by conventional and well-known electroplating processes of the tin-nickel alloy. These 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 3,940.31 ^ 9, all of which are 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 about 65% tin and 35% tin. nickel that represents the atomic composition of SnNi. The plating bath contains a sufficient amount 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 Information Sheet Technique 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 -4 cm (10 millionths (0.00001) of an inch), preferably at least about 5.08 x 10"cm (20 millionths (0.00002) of an inch), and more preferably at least about 1.27 x 10 -4 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 about 0.00508 cm (2,000 millionths (0.002) of an inch), preferably about 0.00254 cm (1,000 millionths (0.001) of an inch), and more preferably about 0.00127 cm (500 millionths (0.0005) ) of one inch), should not be exceeded. Placed on layer 20 of the tin-nickel alloy, there is a layer 24 comprised of a non-precious refractory metal compound such as 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 which is preferred. The layer 24 provides resistance to wear and abrasion and the desired color or appearance, such as, for example, polished bronze. The layer 24 is deposited on layer 22 by any well known and conventional deposition or plating processes such as vacuum coating, reactive ion sputter plating.and similar The preferred method is plating with reactive ion spray. Reactive ion spray is well known in the art and generally similar to an ion spray deposition except that a reactive gas which reacts with the material that is targeted or dislodged is introduced into the chamber. Thus, 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 the circle, the color of the zirconium nitride can be made to be similar to that of the bronze of various shades. Ion spraying techniques and equipment are well known in the art and are described, inter alia, in T. Van Vorous, "Planar Magnetron Sputtering; A New Industrial Coating Technique ", Solid State Technology, December 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. Shortly, in the ion spray deposition process the metal such as titanium or zirconium that is targeted or 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 or discharge the titanium or zirconium, the material of the target or target evicted or charged is then typically deposited as a coating film on the substrate. 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 raillonéßimaßß (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 in general is not critical and depends on considerations such as cost, in general a thickness of approximately 7.62 x 10 cm (30 millionths (0.00003) of an inch), preferably approximately 6.35 x 10"cm (25 millionths (0.000025) of an inch), and more preferably in the" approximate 5.08 x 10"cm (20 millionths (0.000020) of an inch) shape It should not be exceeded Zirconium nitride is the preferred coating material because it provides more closely the appearance of "polished bronze." For the invention to be understood more easily, the following example is provided. does not limit the invention to it.

EXAMPLE 1 Door shields, made of brass, are placed in a soaking bath, conventional, containing soaps, detergents, deflocculants and the like, standard and well known, which is maintained at a pH of 8.9 - 9.2 and at a temperature of 82.2-93.3 ° C (180 - 200 ° F) for 30 minutes. The brass shields 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, well-known soaps, detergents, deflocculates and the like. . After the ultrasonic cleaning, the ornamental plates or shields are rinsed and placed in a conventional alkaline electric cleaning bath for approximately two minutes. The electric cleaning bath contains an insoluble submerged 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 acid activator bath for about one minute. 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 shields or ornamental plates are then rinsed twice and placed in a bright nickel plating bath for about 24 minutes. The bright nickel bath is generally a conventional bath which is maintained at a temperature of approximately 54.4 - 65.5 ° C (130-150 ° F), a pH of about 4.0 - 4.8, and contains NiSO, NiCl2, boric acid and brighteners. A layer of bright nickel of an average thickness of approximately 0.001905 cm (750 millionths (0.00075) of an inch) is deposited on the substratum. The bright nickel plated ornamental plates or plates are rinsed twice and placed in a tin-nickel plating bath for approximately 7 1/2 minutes. The bath is maintained at a temperature of about 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 conventional and well-known complexing and wetting agents. A layer of tin-nickel of an average thickness of approximately . 08 x 10 -4 cm (200 millionths (0.0002) of an inch), is deposited on the surface of the bright nickel layer. Coatings or ornamental plates plated with the tin-nickel alloy are placed in an ion spray plating container. This container is a stainless steel vacuum vessel marketed by Leybold A.G. from Germany. The container in general is 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 argon flow velocity in the chamber. In addition, two sources of nitrogen gas are connected to the chamber by an adjustable valve to vary the flow rate of the nitrogen in the chamber. Two pairs of target or target mounts of the magnetron type are mounted in a spaced relationship far into the chamber and are 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. Target or target material comprises zirconium. A substrate carrier carrying 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 a variable speed motor to transport the Substrates between each pair of target mounts or magnetron target. The carrier or conveyor is electrically conductive and electrically connected to the negative output of a power supply of C.C. variable. The shields or ornamental plated plates, are mounted on the 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 electric resistance heater. The target or target material is cleaned by spraying or cathodic deposition to remove contaminants from its surface. Spray cleaning or cathodic deposition 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 the argon gas at the rate of approximately 200 standard cubic centimeters per minute . A pressure of almost 3 x 10 millibars is maintained during spray cleaning or cathodic deposition.The shields or ornamental plates are then cleaned by an etching process or acid etching, at low pressure. , at low pressure, is carried out for approximately 5 minutes and involves the application of a negative CC potential which is increased over a period of one minute from about 1200 to about 1400 volts to the shields or ornamental plates and by applying DC power to the cathodes to achieve a current flow of approximately 3.6 amps Argon gas is introduced at a rate which increases over a period of one minute from approximately 800 to approximately 1000 standard centimeter-cubic meters per minute , and the pressure is maintained at approximately 1.1 x 10, millibars.The shields or ornamental plates are rotated between the Target or magnetron targets at a rate of one revolution per minute. The shields or ornamental plates are then subjected to a cleaning process of acid attack, 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 beginning the flow rate is 500 sccm and after 10 minutes the flow rate is 650 sccm and remains at 650 sccm for the rest of the acid attack process at high pressure), the pressure is maintained at approximately 2 x _1 10 millibars, and a negative potential which is increased 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 vessel is maintained at approximately 2 x 10"millibars.

The shields or ornamental plates are then subjected to another cleaning process, by acid attack, of low pressure, for approximately five minutes. During this process of cleaning by acid attack, at low pressure, a negative potential of approximately 1400 volts is applied to the shields or ornamental plates, an energy of C.C. 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 about 800 sccm (standard cubic centimeters per minute) to approximately 1000 sccm. The pressure is maintained at approximately 1.1 x 10 millibars and the shields or ornamental plates are rotated at about one rpm. The target or target material is again cleaned by sputtering or cathodic deposition for approximately one minute by applying enough 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 material on the shields or ornamental plates. The protections are removed and a layer of zirconium nitride that has an average thickness of approximately 3.55 x 10"cm (14 millionths (0.000014) of an inch), is deposited on the tin-nickel layer by reactive ion spray during a period of 14 minutes. A negative potential of approximately 200 volts DC is applied to the shields or ornamental plates while the DC power 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 the two sources. A source introduces nitrogen at a flow rate generally in a permanent state, of approximately 40 sccm. The other source is variable. The variable source is regulated so as to maintain a partial ionic current of 6.3 x 10"amperes, with the variable flow of nitrogen being increased or reduced when necessary to maintain the partial ion current at its predetermined value. container is maintained at approximately 7.5 x 10"millibars.

The ornamental plates coated with zirconium nitride 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 about 2 x 10-1 millibars, and argon gas is introduced at a speed 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 which are not described in the embodiments. 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 (15)

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

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

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 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 4, characterized in that the metallic substrate is comprised of bronze.

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

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

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

9. An article comprising a substrate having on at least a portion of its surface a multi-layer coating having a bronze color, 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 a tin-nickel alloy; and a top layer on at least a portion of the second layer comprised of a zirconium compound.

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

11. The article according to claim 10, characterized in that the circo-nium compound is zirconium nitride.

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

13. The article according to claim 9, characterized in that the zirconium compound is zirconium nitride.

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

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