HARD CHROMIUM PLATING FROM A TRIVALENT PLATING BATH

Trivalent chromium salts were used with organic complexing agents, oxi dation inhibitors, and conductivity agents to prepare plating baths, H ull Cell tests and thickness measurements provided the information to determine the optimum bath composition and operating conditions, With this bath operating in the pH range of 0.1 to 1.0, deposits more than 50 mu m thick were plated, It is suggested that polynuclear coordinati on compounds form from hydroxyl ion complexes at high pH, such as pH 3 , which is used in commercial trivalent chromium plating baths, These compounds prevent the plating of thick deposits.