MXPA00010984A - Coating compositions containing nickel and boron - Google Patents

Abstract

This invention is directed to plating using a coating bath that provides a hard, wear and corrosion resistant, ductile coating on a substrate, said bath having a pH of about 10 to about 14 and comprising:(1) about 0.175 to about 2.10 moles per gallon of coating bath of nickel ions;(2) an effective amount of lead tungstate to stabilize the bath and to form a continuous coating free from blotches without any substantial deposition of lead tungstate in the coating;(3) an effective amount of metal ion complexing agent in an amount sufficient to inhibit precipitation of said metal ions from the coating bath;and (4) an effective amount of a borohydride reducing agent.

Description

NICKEL AND BORON CONTAINING COMPOSITIONS This invention is a continuation in part of United States Patent Application Number 09 / 074,703 filed May 8, 1998: BACKGROUND OF THE INVENTION This invention relates to novel metal coatings exhibiting exceptional hardness. More particularly, the invention relates to metal coatings containing nickel and boron and to the reductive deposition of coatings on the surfaces of the substrate articles from aqueous solutions, at an alkaline pH. The plating or deposition of metal alloys by electrochemical or chemical reduction of metal ions on the surface of an article, to modify its surface characteristics, both for decorative and functional purposes, is well known in the art. Of particular commercial importance is the deposition of metallic / metallic alloy coatings on both metallic and non-metallic activated substrates in order to reinforce surface hardness and resistance to corrosion and wear. Nickel-boron and nickel-boron alloy coatings are recognized in the art for their hardness and associated wear resistance. The patent literature reflects that a research and development effort is being made in the area of nickel and boron coatings with the aim of producing coatings with much more resistance to corrosion and even harder. For example, refer to U.S. Patent Nos. 5,019,163; 3,738,849; 3,674,447; 3,342,338; 3,378,400; 3,045.3342; and 726,710. The technique has recognized that when borohydride is used in a nickel / boron plating bath a harder coating is achieved. However, borohydride is very unstable in the bath. The solution to the stability problem has been to add stabilizers such as thallium sulfate or lead chloride. The addition of the stabilizers has the effect of interfering with the formation of the nickel coating, thus having a negative impact on the hardness of the coating. As the stabilizer is not co-deposited in the coating, according to the present invention, the nickel coating is markedly harder than those described in the prior art. To date, nickel / boron coatings have always included a stabilizer as a third element. The only exception is a dimethylborane coating. This type of coating does not have the stabilizer present therein. This process has very limited application because the bath has a very slow deposit velocity and the coating is very thin. The deposit speeds are of the order of 0.00015 inches per hour. The thickness of the deposit is limited to approximately 0.0001-0.0002 inches. These deposits are too thin to be used for wear surfaces. Therefore, a general objective of this invention is to provide a coated article of manufacture on at least one surface portion with a tough, ductile, corrosion-resistant, wear-resistant metallic coating, comprising both nickel and boron, to reduce thus the negative impact produced by the co-deposition of a stabilizer. Still another object of the invention is to provide coating baths from which a hard, ductile, corrosion and wear resistant coating can be deposited on at least a portion of the surface of a metal or an activated non-metallic substrate.

SUMMARY OF THE INVENTION According to the present invention, a novel metallic coating composition containing both nickel and boron and lead tungstate is provided. The composition of the coating may contain other metal ions such as cobalt. The coating composition is particularly useful for depositing on a surface of a manufacturing article, which is exposed to corrosive conditions or is subjected to sliding or rubbing contact with another surface, under abnormal pressure of support and wear. The metal coating composition of this invention comprises about 67.5 to 97.0 weight percent nickel, between about 0 and 48.5 weight percent cobalt, about 2.5 to about 10 weight percent boron. The cobalt may be substituted by nickel in up to about 50% nickel. Preferably, the substitution of cobalt with nickel is less than 25% of the nickel. A preferred range for the nickel coating is from 94 to 97 percent nickel and from 3 to 6 percent boron, the percentages are by weight. The coating is remarkably hard and yet is ductile, and is highly resistant to corrosion and wear. It has surprisingly been found that by using a lead tungstate to stabilize the nickel-boron plating bath it is possible to form a nickel / boron coating with an even higher hardness than previously achieved. Stabilizers have conventionally been added to these plating baths to retard the precipitation of the reducing agent in the coating bath itself. These stabilizers are co-deposited with the nickel coating. This co-deposition prevented the complete formation of the nickel coating, thus limiting the hardness and wear resistance of the nickel and boron coating. The discovery was that by substantially avoiding co-deposition of the stabilizer, the hardness of the nickel / boron coating increased. According to the present invention, the lead tungstate precipitates as a particle in the plating bath, instead of co-deposited in the coating. These particles can be removed by trapping the particles in a filtration system. The present coating is preferably applied to a substrate in anelectrolytic form, by contacting the substrate with a coating bath containing nickel ions, lead tungstate ions, a metal ion complexing agent and a borohydride reducing agent, at a pH of about 10 to 14, and at an elevated temperature of about 180 to 210 ° F. The coating can be veneered at lower temperatures after the plating is initiated within a temperature range of about 180 to 210 ° F.

DETAILED DESCRIPTION OF THE INVENTION Substrates suitable for anelectrolytic deposition are surfaces termed catalytically active surfaces, including those composed of nickel, cobalt, iron, steel, aluminum, zinc, palladium, platinum, copper, brass, chromium, tungsten, titanium , tin, silver, carbon, graphite and alloys thereof. These materials function catalytically to produce a reduction of the metal ions in the plating bath, by borohydride, and in this way the deposition of the metal alloy on the surface of the substrate in contact with the plating bath is obtained. Aluminum plating normally requires a protective coating to prevent dissolution during plating. Non-metallic substrates, for example glass, ceramics and plastics in general are non-catalytic materials, however, these substances can be sensitized to be catalytically active, if a film of one of the catalytic materials is produced on its surface. This is achieved by a variety of techniques known to experts. A preferred method involves bathing the glass, ceramic or plastic articles in a solution of stannous chloride and then contacting the treated surface with a palladium chloride solution. In this way, a thin film of palladium is reduced on the treated surface. The article can then be veneered or coated with the metal composition according to this invention, by contact with a coating bath as detailed below. It should be noted that magnesium, tungsten, carbide and some plastics have exhibited some resistance to the deposition of the coatings herein. A coating bath for deposition in the coatings of the present invention comprises: (1) Nickel ions, between about 0.175 to 2.10 moles per gallon. The calculations are based on a nickel chloride range of 0.05 to 0.6 pounds per gallon. A preferred range of nickel ions is from about 0.35 to about 1.57 moles per gallon, based on 0.1 to about 0.45 pounds per gallon of nickel chloride. (2) Cobalt ions, up to 1.05 moles per gallon, but not more than 50% nickel present in the bath; (3) an effective amount of a chemical agent to adjust the pH of the bath between about 10 and about 14; (4) about 2.26 to about 6,795 moles per gallon of metal ion complexing agent, preferably 3.3 to 3.8 moles per gallon. (5) Approximately 0.01 to about 0.8 moles per gallon of the coating bath of a borohydride reducing agent, based on sodium borohydride, preferably 0.020 to 0.033 moles per gallon of the bath. (6) An effective amount of lead tungstate as a stabilizer, which may vary from about 0.0143 per gram per gallon to about 0.30 grams per gallon, preferably about 0. 0182 to approximately 0.08 grams per gallon. The borohydride reducing agent may be selected from known borohydrides having a good degree of water solubility and stability in aqueous solutions. Sodium borohydride is preferred. In addition, substituted borohydrides in which no more than three hydrogen atoms of the borohydride ion have been replaced may be used. Sodium trimethoxyborohydride [NaB (0CH3) 3H] is an illustrative example of this type of compound. The coating bath preferably has a pH of about 12 to 14. Better results have been observed when the pH of the bath is conserved during the coating process within this range and more preferably at about pH 13.5. The pH adjustment of the bath can be achieved by the addition of any wide variety of alkaline salts or solutions thereof. The preferred chemical agents to establish and maintain the pH of the bath are the alkali metal hydroxides, in particular sodium and potassium hydroxide and ammonium hydroxide. Ammonium hydroxide offers an additional advantage since the ammonium ion can function to assist the complexing of the metal ion in the coating bath. Due to the high alkalinity of the coating bath, a sequestering or metal ion complexing agent is required to prevent the precipitation of metal ions, for example nickel and other metal hydroxides or other basic salts. It is also important that the metal ion complexing agent works to decrease the reactivity of the metal ion, the complexed or sequestered metal ions have minimal reactivity with the borohydride ions in the bulk solution, but do not react on the catalytic surfaces of the substrates in the contact with the solution. The term "catalytic surface" refers to the surface of any article composed of the catalytic materials mentioned above or to the surface of a non-catalytic material that has been sensitized by the application of a film of the catalytic materials on its surface. Suitable complexing or sequestering agents for this invention include ammonia and organic complexing agents that contain one or more of the following functional groups: primary amino, secondary amino, tertiary amino, imino, carboxy and hydroxy. Many metal ion complexing agents are known in the art. Preferred complexing agents are ethylenediamine, diethylene triamine, triethylene tetramine, organic acids, oxalic acid, citric acid, tartaric acid and ethylenediamine tetraacetic acid and water soluble salts thereof. The most preferred is ethylenediamine. Approximately 2.26 to 6.795 moles per gallon of complexing agent are used per gallon of coating bath. This calculation was based on 0.3 to about 0.9 pounds per gallon of ethylenediamine. The best results have been obtained when approximately 3.39 to approximately 3.77 moles per gallon of the coating bath are used. This calculation was based on approximately 0.45 to approximately 0.5 pounds per gallon of ethylenediamine per gallon of coating bath. Metal ions such as nickel ions in the coating bath are provided by the addition to the bath of the respective water soluble salts. Any salt of these metals that has an anionic component that is non-antagonistic to the coating process in question is suitable. Examples of salts of oxidizing acids, for example chlorate salts, are not suitable as they react with the borohydride reducing agent in the bath. Chlorides, sulphates, formations, acetates and other salts of cobalt and nickel whose anions are essentially inert with respect to the other ingredients of the bath dal? Alkaline coating are satisfactory. The lead tungstate can be added to the plating bath from a concentrate containing a pH modifier and a complexing agent. The complexing agent can be selected from those mentioned above. The preferred complexing agent is ethylene diamine. The concentrate contains approximately 2 to approximately 31 grams per gallon of lead tungstate. The preferred range of lead tungstate is between about 7 and about 12 grams per gallon. The concentration range of the complexing agent is from 100 to 700 milliliters. The preferred range of the complexing agent is between about 300 and 400 milliliters. The pH of the mixture is greater than 8, preferably 10.5. The pH modifier is selected from bases such as sodium hydroxide, which are not harmful to the plating bath. The concentrate is added to the bath so that during dilution, the concentration of the lead tungstate in the bath can vary between about 0.0143 and 0.30 grams per gallon of the plating bath. The preferred concentration range is between about 0.0182 to about 0.082 grams per gallon of plating bath. The plating bath is typically prepared by forming an aqueous solution of the appropriate amounts of nickel and cobalt salts, adding the complexing agent or agents and the stabilizer, adjusting the pH between about 12 and 14, heating to about 195 ° F, filtering and finally, immediately before introducing the substrate into the bath, adding the required amounts of sodium borohydride (typically in aqueous alkaline solution). The article to be coated or veneered using a bath according to this invention is prepared by mechanical cleaning, degreasing, anodic alkaline cleaning and finally by etching in an acid bath, according to standard practice in the metal plating technique . The substrate can be masked, if necessary, to allow deposition of the metal alloy coating only on the selected surfaces. Although the coatings of the present generally exhibit excellent adhesion to properly prepared substrate surfaces, in cases where the adhesion of the coating is critical or where certain adhesive problems were experienced.The adhesion of the coating can usually be reinforced by depositing a nickel-fixing layer, electrochemically, on the surface of the substrate, before applying the coating herein. The clean article or whose surface has been prepared, is submerged in the hot bath (between approximately 180 and 210 ° F) on the selected surface. Although the coatings of the present generally exhibit excellent adhesion to suitably prepared substrate surfaces, in cases where the adhesion of the coating is critical or where there are certain adhesion problems, the adhesion of the coating can usually be improved by depositing an improvement layer on the substrate. adhesion, nickel, electrochemically on the surface of the substrate before applying the coating of the present. The clean article or whose surface has been prepared in some other form, is immersed in the hot coating bath (approximately 180 to 210 ° F) to start the coating process. The process continues until the deposition of the coating has progressed to the desired thickness or until the metal ions have been exhausted from the solution. The deposition rates vary under the process conditions herein of between about 0.1 thousandths of an inch to about 1.5 thousandths of an inch per hour. The preferred range of plating bath ingredients comprises of approximation < 0.35 to about 1.57 moles per gallon of nickel, about 0.0182 to about 0.08 moles per gallon of lead tungstate ions, about 0.017 to about 0.035 moles per gallon of borohydride. The proportion of nickel, cobalt, boron and lead tungstate in the coatings herein can be adjusted by varying the relative amounts of the metal salt components and the borohydride in the coating bath. According to the present invention, under normal conditions of use of the coating bath, lead tungstate and borohydride reducing agent is added to the bath, every hour, in an amount equivalent to its use in the initial preparation of the bath. The need to replenish the coating baths of the present with lead tungstate and borohydride depends on the ratio between coating bath volume and surface area being coated. Therefore, the replenishment of the lead tungstate and borohydride to the coating bath of the present would normally be required when very small surface areas are to be treated. A bath gallon prepared according to the embodiments of the present invention will coat approximately 144 square inches to a thickness of 1 mil. To achieve this result, the bath is replenished with lead tungstate and borohydride according to the above description, as its components become depleted of the solution. The pH of the coating bath will tend to fall during the coating process and should be checked periodically to ensure it is within the preferred pH range of about 12 and 14. It has been found that any problems of maintaining the pH through the use of a coating bath may be decreased simply by the use of a highly alkaline solution (concentrated sodium hydroxide) of borohydride to replenish the borohydride content of the bath, as required. The rate of deposition of the coating from the anelectrolytic coating bath of the present is from about 0.1 to about 1 mil of an inch and depends on the bath temperature, the pH and the concentration of the metal ion. The deposition rate of most metal substrates from freshly prepared coating baths at a preferred temperature between about 185 and 195 ° F is about 1 mil of an inch per hour. The practical aspects for carrying out an anelectrolytic coating process are known in the art. These processes are shown in the following United States Patents: No. 5,109,613 issued to McComas on May 28, 1991; No. 3,338,726 granted to Berzins on August 19, 1967; No. 3,096,182 granted to Berzins on July 2, 1963; No. 3,045,334 granted to Berzins on October 1, 1958; No. 3,378,400 granted to Sickles on April 16, 1968; and No. 2,658,841 issued to Gutzeit and Krieg on November 10, 1953; the exhibitions of which are incorporated here as a reference. The anelectrolytic nickel coatings of the present invention exhibit unprecedented hardness and concomitant wear resistance. They are highly ductile allowing the coating to flex with the substrate while retaining a strong bond to the coated material. The coatings are amorphous and non-porous. After the nickel coating is deposited on a substrate, the conventional step in the prior art is to heat treat the coating to achieve maximum hardness. Prior to the heat treatment, the nickel / boron coatings of the prior art had a Knoop hardness of about 925. After the heat treatment, the nickel / boron coatings of the prior art had a Knoop hardness below 1373. In contrast, When using lead tungstate as a stabilizer, the Knoop hardness of the nickel / boron coating before the heat treatment is about 1000. After the heat treatment, the Knoop hardness of the nickel / boron coating is higher than 1375. The heat treatment is achieved at a temperature of about 375 to about 750 ° F for a period of about one to about 24 hours. Shorter times are preferred, from about one to two hours for higher temperatures of between about 550-750 ° F. It has been shown that the longer thermal treatments are advantageous at temperature intervals less than about 375 to 450 ° F. The nickel / boron coating structure changes during the heat treatment. Before heat treatment, nickel and boron apparently combine to form an alloy. After the heat treatment, nickel boride is formed. The coating appears to be a dispersion of nickel boride within the nickel / boron alloy. Any thickness of the coating can be achieved. Coating thicknesses greater than 0.0001 inch to 0.04 inch or greater may occur. Conventional wear coatings having a thickness range of about 0.0005 inches to about 0.004 inches may occur. The coatings of the present have a wide range of applications, which will be recognized by those skilled in the art. They have particular utility for coating surfaces of articles that in their normal use are subjected to highly abrasive, rubbing or sliding conditions, under high temperatures / pressures. These high wear conditions are found at many points in the construction of tools, internal combustion engines that include gas turbine engines, transmissions and a wide variety of heavy equipment construction applications. The following examples provide details of the bath compositions, the process conditions and the representative coating compositions and properties of this invention. The example illustrates the invention and should in no way be taken as limiting the scope thereof.

EXAMPLE One unit of a batch of one (1) g of coating bath was prepared in the following manner. For the purposes of this example, four solutions were prepared: A (the bath), B (the reducer), C (the stabilizer) and D (the resupplying bath). First, batches of one gallon of each solution were prepared. Solution A (the bath) consisted of deionized water, 0.2 pounds of nickel chloride, 0.5 pounds of ethylenediamine, and 0.33 pounds of sodium hydroxide. Solution B (the reducer) consisted of deionized water, 2.5 pounds of sodium hydroxide and 0.8 pounds of sodium borohydride. Solution C (the stabilizer) consisted of deionized water, 100 grams of sodium hydroxide and 10 grams of lead tungstate and 400 ml of ethylenediamine. Solution D (the bath replenishment) consisted of deionized water, 0.6 pounds of nickel chloride, 1.5 pounds of ethylenediamine and 1.0 pounds of sodium hydroxide (solution D was the same as solution A, but with less water). Solution A was heated to 192 ° F: two 1"x 11 foot stainless steel panels were cleaned with detergent, so that the panels were free of oil and dirt, the panels were fixed to a steel wire and placed in a solution of 30% HCl and 20% HS04 for 60 seconds in order to activate the pieces Just before the panels were placed inside the plating bath, 10 milliliters of Solution B mixed with 10 milliliters of Solution C to the heated Solution A. For solution C, 7 to 12 milliliters can be used.After 30 minutes, Solution A was titrated to determine the presence and amount of sodium borohydride, another 10 milliliters of Solution B and 10 milliliters of Solution C were mixed and added after every 30 minutes of plating.The plating was continued for 3 hours.After 3 hours, the panels were removed from the bath and measured to determine the thickness of the deposit. heat was made at 750 ° F for ninety minutes. The panels measured 0.0347 inches before plating and 0.0407 inches after plating, showing a total thickness increase of 0.006 inches or 0.003 inches per side or a deposition rate of 0.001 inches per hour. The panels did not present blisters, were continuous and did not present porosity. The panels were cut, assembled, cut in cross section and checked for hardness according to the standard microhardness test studies. The coating could then be examined in its profile, showing the interface area between the coating and the substrate. This area is free of voids and foreign matter. The hardness of the coating panels was measured using the Knoop indentor with a 100 gram load. The hardness values before the heat treatment were from about 950 to about 1050. The hardness values after the thermal treatments were the following: 1545, 1685, 1610, 1785, 1660, 1710, 1690, 1820, 1730 and 1710. If the highest and lowest value are removed and the rest of the values are averaged to obtain a final hardness value of 1697. This shows that the novel plating composition produces highly reproducible hardness values. These values are at least 25% higher in hardness than other nickel and boron coatings of the prior art and, therefore, showed up to 300% improvement in wear resistance. The remaining plating samples were analyzed using ICP technology to find the quantitative composition of the coating. The ICP (X-ray) results showed a composition of 95.5% nickel and 4.5% boron and trace elements with a probable error of 0.5%. Prior to the heat treatment, the coating was a nickel / boron alloy. After the heat treatment, the coating had a nickel boride dispersion in the nickel / boron alloy. The thermally treated coatings according to the present invention have a Knoop hardness value of between about 1400 and about 2200. These values are higher than the best previously reported hardness values for nickel and boron anelectrolytic coatings. The present invention of the use of lead tungstate was compared to the nickel plate baths of the prior art using thallium as a stabilizer. In Bellis, U.S. Patent Number 3,674,447, Example 3 produced a coating of 93% nickel, 3.5% boron, 3.5% thallium with a knoop hardness of 900-1000. In Klein, U.S. Patent No. 3,295,999, Example 2 produced a coating of 93% nickel, 4% boron and 3% thallium with a knoop hardness of 1000-1100. In McComas, U.S. Patent Number 5,109,613, Example 1, produced a coating of 90% nickel, 4% boron, 4% cobalt, 2% thallium with a knoop hardness of 1200-1300. The knoop hardness of the Bellis and McComas coatings before the heat treatment was measured and was less than about 925. These comparisons show the unexpected results of the use of lead tungstate as a stabilizer, achieving knooo hardness of between 1385 and 2200 after the heat treatment and 950 and 1050 before the heat treatment, with a continuous coating free of blisters.

The concentration of lead tungstate in the bath varied producing the following results. In grams per gallon of lead tungstate in the bath, at 0.0025 grams the bath was unstable, at 0.003 grams a slight improvement was observed, at 0.008 grams the deposition rate was uncontrollable with a soft fall after 10 minutes, at 0.0104 grams the bath was unstable with severe sedimentation, at 0.013 grams the bath was unstable with severe sedimentation, at 0.0156 grams the bath was unstable with severe sedimentation, at 0.0182 grams the bath was initially unstable but it was corrected automatically with time, at 0.0208 grams it was they obtained good results, at 0.05 grams llent results were obtained, at 0.56 grams good results were obtained, at 0.06 grams good results, at 0.065 grams good results but low deposition rates, at 0.07 grams the same results, at 0.09 grams deposition rates Minor, at 0.1 grams deposition rates less than approximately 0.0004 mils per hour, to 0.2 gr At slower deposition speeds of approximately 0.0003 thousandths of an inch / hour, at 0.3 grams the same, at 0.4 grams the plating stops. At approximately 0.0104 grams and 0.014 grams per gallon of lead tungstate a non-uniform coating was observed. The coating covered the surface with blisters. The structure of the coating was irregular. When the lead tungstate of the bath increased above about 0.0142, the coating was continuous and uniform. The blisters disappeared. These results show that the concentration of lead tungstate in the bath can vary between approximately 0.0142 and 0.30 grams per plating bath geilon. The preferred concentration range is between about 0.0128 grams to about 0.2 grams. In relation to the above description, it should be noted that the proportions, process steps and optimal ingredients of the invention, to include variations in size, materials, conformation, shape, function and form of operation, assembly and use, will be considered evident and obvious to the experts, and all ratios equivalent to those described in the specification are encompassed by this invention. Therefore, the above is considered an illustrative description only of the principles of this invention. In addition, as several modifications and changes will occur to the experts in this field, it is not desired to limit the invention to the exact operation and construction shown and described here, consequently, all the modifications and equivalents that are within the scope of this invention.

Claims (43)

1. CLAIMS; An article having an amorphous wear-resistant coating and comprising a nickel borohydride dispersed in a nickel / boron alloy, wherein the nickel is between 67.5 and 97.0% by weight and the boron is between 2.5 and 10% by weight , and the coating has a Knoop hardness greater than 1385 and where the coating is continuous and free of blisters. The article according to claim 1, wherein the wear-resistant coating comprises from about 93 to 97% by weight of nickel and from 7 to 3% by weight of boron. The article according to claim 2, wherein the wear resistant coating has a Knoop hardness of at least about 1400 to about 2200. 4. The article according to claim 1, wherein the wear-resistant coating has a thickness of approximately 0.001 to 0.04 in. < adas The article according to claim 1, wherein the cobalt is replaced by nickel up to about 50% nickel. 6. A coating bath to provide a ductile coating, resistant to corrosion and wear, hard, which is deposited on a substrate, the bathroom has a pH of about 10 to about 14 and comprises: (1) between about 0.175 and 2.10 moles per gallon of nickel ion coating bath; (2) an effective amount of lead tungstate to stabilize the bath and to form a continuous blister-free coating, without substantial deposition of the lead tungstate in the coating; (3) an effective amount of the complexing agent for metal ions in an amount sufficient to inhibit the precipitation of the metal ions from the coating bath; (4) an effective amount of a borohydride reducing agent; and (5) optionally up to 1.05 moles per gallon of cobalt. The coating bath according to claim 6, wherein the bath contains between about 0.0156 and 0.3 grams per gallon of lead tungstate as a stabilizer. 8. The coating bath according to the claim 6, wherein the complexing agent of the metal ion is selected from the group consisting of water soluble salts. Extract of tartaric acid, citric acid, oxalic acid, ethylenediamine, diethylene triamine, triethylene riamine, ethylenediamine tetraacetic acid and ammonia. 9. The coating bath according to claim 8, wherein the metal ion complexing agent is ethylenediamine. The coating bath according to claim 7, wherein the borohydride reducing agent is selected from the group consisting of sodium borohydride, potassium borohydride, sodium trimethoxyborohydride and potassium trimethoxyborohydride. 11. The coating bath according to claim 10, wherein the borohydride reducing agent is sodium borohydride. 12. The coating bath according to claim 10, wherein the borohydride concentration is between about 0.017 and 0.035 moles per gallon. The coating bath according to claim 6, wherein the concentration of the metal ion complexing compound is between about 2.26 and about 6,795 moles per gallon of the coating bath. 14. The coating bath according to claim 7, wherein the concentration of the nickel ion is between about 0.35 and 1.57 moles per gallon. 15. The coating bath according to claim 6, wherein the concentration of the lead tungstate ion is between about 0.0182 and 0.25. 5 grams per gallon. 16. A method for the deposition of a metal coating containing nickel and boron, on a substrate, the method consists of: providing a plating bath according to claim 6; submerging the substrate to be coated within the bath; and depositing the coating anelectrolytically on the substrate. 17. The method according to claim 16, wherein the pH of the bath before the coating is adjusted between about 12 and 14. The method according to claim 16, wherein the metal ion complexing agent comprises a The compound selected from the group consisting of ethylenediamine, tartaric acid salts soluble in water and ammonia. 19. The method according to claim 18, wherein the metal ion complexing agent is 25 ethylenediamine. 20. The method according to claim 16, wherein the borohydride reducing agent is selected from the group consisting of sodium borohydride, potassium borohydride, sodium trimethoxyborohydride and 5 potassium trimethoxy borohydride. 21. The method according to claim 20, wherein the borohydride reducing agent is sodium borohydride. 22. The method according to claim 16, wherein the metal coating is heat treated. 23. The product produced by the method of claim 16, excluding a heat treatment step and having a thickness greater than 0.00028 inches, wherein the coating consists essentially of nickel 15 and boron. 24. The product produced by the method of claim 22, which has a thickness greater than about 0.0001 inches. 25. The product produced by the method of Claim 23, which has a thickness of about 0. 001 to approximately 0.04 inches. 26. The product produced by the method of claim 22, which has a Knoop hardness of at least 1375. 27. The product produced by the method of The product produced by the method of claim 23, which has a Knoop hardness of more than 950 to about 1050, has a Knoop hardness of about 1400 to 2200. The product produced by the method of claim 23 has a Knoop hardness of more than 950 to about 1050. 29. A concentrate having a pH greater than 8 and containing between about 2 and about 31 grams per gallon of lead tungstate, about 100 to about 700 ml of ethylenediamine as a metal ion complexing agent, and a pH modifier. 30. A concentrate according to claim 29, containing 300 to 400 ml of ethylenediamine. 31. A concentrate having a pH of about 10.5 which contains about 7 to about 12 grams per gallon of lead tungstate, about 300 to 400 ml of ethylenediamine and a pH modifier. 32. A coating bath to provide a hard, wear and corrosion resistant, ductile coating that is deposited on a substrate, the bath has a pH of between about 12 and about 14 and comprises: (1) between about 0.35 and 1.57 moles per gallon of nickel ion coating bath; (2) between approximately 0.0208 and 0.08 grams ÜÜÍ jÍÍ ^ ^ ^^Í j j j j j j j j________________ per gallon of lead tungstate as a stabilizer; (3) between about 3.3 and 3.8 moles per gallon of the metal ion complexing agent to inhibit the precipitation of the metal ions from the coating bath; (4) between about 0.045 and 0.08 moles per gallon of a borohydride reducing agent; and (5) optionally cobalt. 33. An article having an amorphous wear-resistant coating, wherein the coating comprises 67.5 to 97% by weight of nickel, 2.? at 10% by weight of boron, the coating has a thickness greater than 0.0003 inches and a Knoop hardness of at least about 950-1050 and wherein the coating has not been heat treated and is continuous, being free of blisters. 34. An article according to claim 33, wherein the wear-resistant coating comprises between about 93 and 97% by weight of nickel and 3 to 7% by weight of boron. 35. An article according to claim 34, wherein the wear resistant coating has a thickness between about 0.001 and 0.04 inches. 36. An article according to claim 34, wherein the cobalt is replaced by nickel up to about 50% nickel. 37. The coating bath produced according to claim 6, wherein the bath is formed 5 by combining the ingredients (1), (2), (3), (4) and optionally (5). 38. An article according to claim 4, wherein the coating has a thickness greater than 0.00025 inches. 39. An article according to claim 4, wherein the article is a metal. 40. An article that has an amorphous, continuous, wear-resistant, blister-free coating, consisting essentially of nickel boride 15 dispersed in a nickel / boron alloy, wherein the nickel is at 67.5 to 97.0% by weight and the boron is between 20.5 and 10% by weight and the coating has a Knoop hardness greater than about 1385. 41. An article that it has an amorphous, wear-resistant, continuous, blister-free coating, wherein the coating consists essentially of 67.5 to 97% by weight of nickel, 0.5 to 10% by weight of boron, the coating has a thickness greater than 0.0003 inches and a Knoop hardness of at least about 950-1050 and 25 where the coating has not been heat treated. 42. The product produced by the method of claim 16, which excludes a heat treatment step and which has a thickness greater than 0.00028 inches, wherein the concentration of the lead or tungstate in the coating is limited to trace amounts. 43. The product produced by the method of claim 21, wherein the concentration of the lead or tungstate in the coating is limited to trace amounts.