Abstract: A process electroplates a metal workpiece with thin dense chromium. The workpiece is first activated by submerging in an aqueous solution of sulfuric acid and a biflouride salt, preferably ammonium biflouride. The biflouride salt reacts to form HF. A preferred activating bath has a 35% sulfuric acid concentration of 4 ounces per gallon of ammonium biflouride salts. A positive DC voltage is applied between the workpiece and a cathode in the bath. The workpiece is then submerged in a chromium plating bath formed of chromic acid sulfate to produce the chromium plate. A DC plating voltage initially 3 volts produces a current flow of about 1.5-2.5 amps per square inch of workpiece area. In a preferred process, the plating voltage is continuously increased to an eventual value of about 4.5 v. The process is particularly suited to plating cobalt-chromium alloys.

Abstract: A movable joint has a first portion and a second portion and at least a deposition of chromium material forming an interface between the first and second portions. The first portion has an outer surface. The second portion also has an outer surface. The deposition of chromium material forms an interface between the outer surface of the first portion and the outer surface of the second portion.