Movable joint and method for coating movable joints

Abstract

In a process of electroplating a metal work piece with thin dense chromium, the steps of submerging the metal work piece in a 35% sulfuric acid solution having about 4 ounces per gallon HF as ammonium biflouride salts, and subsequently submerging the metal work piece in a thin dense chromium plating bath having an initial direct current of about 3 volts, the amperages being at about 1.5-2.5 amps per square inch of cathode area, is provided.

What is claimed is:  
     
         1 . In a process of electroplating a metal work piece with thin dense chromium, the steps comprising: 
 a. submerging the metal work piece in a 35% sulfuric acid solution having about 4 ounces per gallon HF as ammonium biflouride salts; and,    b. subsequently submerging the metal work piece in a thin dense chromium plating bath having an initial direct current of about 3 volts, the amperages being at about 1.5-2.5 amps per square inch of cathode area.    
     
     
         2 . The process of  claim 1  wherein the metal work piece is anodically activated while submerged in said sulfuric acid solution.  
     
     
         3 . The process of  claim 2  wherein the anodic activation comprises delivery of about 3 volts direct current for about 30 seconds.  
     
     
         4 . The process of  claim 3  wherein about 2-3 amps per square inch of cathode area are provided during anodic activation.  
     
     
         5 . The process of  claim 4  wherein said initial direct current voltage is selectively increased over time.  
     
     
         6 . The process of  claim 6  wherein said initial direct current voltage is selectively incrementally increased over time.  
     
     
         7 . The process of  claim 6  wherein said initial direct current voltage is increased to a maximum of about 4.5 volts.  
     
     
         8 . The process of  claim 7  wherein said initial direct current voltage is increased at a rate of 0.1 volt every ten seconds until a voltage of about 4.5 amps is achieved.  
     
     
         9 . A coated implant produced by thin dense chromium plating a work piece, said coated implant having a 100% chromium coating, and a Tabor Abrasion Wear Resistance Wear Index in the range of about 0.9-1.0.  
     
     
         10 . The coated implant of  claim 9  wherein said work piece comprises a metal article.  
     
     
         11 . The coated implant of  claim 10  wherein said work piece comprises a stainless steel article.  
     
     
         12 . The coated implant of  claim 11  wherein said work piece comprises 304 stainless steel.  
     
     
         13 . The coated implant of  claim 11  wherein said work piece comprises 401 stainless steel.  
     
     
         14 . The coated implant of  claim 10  wherein said work piece comprises a cobalt-chromium article.  
     
     
         15 . The coated implant of  claim 10  wherein said work piece comprises a copper article.  
     
     
         16 . The coated implant of  claim 10  wherein said work piece comprises an aluminum article.  
     
     
         17 . A coated implant produced by thin dense chrome plating a work piece, said coated implant having a 100% chromium coating, and a Knoop Test microhardness value in excess of 72 HRC.  
     
     
         18 . A coated implant produced by thin dense chromium plating a work piece, said coated implant having a 100% chromium coating and a Vickers Test microhardness value in excess of 67 HRC.  
     
     
         19 . In a process of electroplating a metal work piece with thin dense chromium, the steps comprising: 
 a. submerging the metal work piece into a thin dense chromium plating solution comprising chromium in the range from about 30 to 35 ounces per gallon of said solution, and sulfuric acid in the range from about 0.3 to 0.35 ounces per gallon of said solution, said solution being at a temperature of about 135-140° Fahrenheit, and carrying a direct current voltage of about 3.2 volts; and,    b. upwardly adjusting said direct current voltage at a rate of about 0.1 volt every ten seconds until a direct current voltage of 4.5 is achieved.