BRONZE IMMERSION PLATING ON MILD STEEL IN CYANTDE-FREE SOLUTIONS

BRONZE IMMERSION PLATING ON MILD STEEL IN CYANTDE-FREE SOLUTIONS

Abstract:

Bronze immersion plating on mild steel was successfully carried out in cyanide-free solutions. The plating solutions contained cupric and stannous chloride:; (hydrated) of various proportions; the most common being 4-10 g/L CuCl2.2H20 and 8-20 g/L SnCl2.2II20. The plating took place in aqueous, non aqueous and akamu media. Non aqueous media comprised of methanol, ethanol, propanol and butanol. The plating was performed at a temperature of 25°C. The addition of NaCl, KC1 and BaCl2 promotes plating rate approximately in that order. Similarly, the addition of thiourea, I,-cysteine and sodium dithionate to the plating solutions enhances coating thickness growth. However, the addition of IIC1 to the plating solutions retards plating rate. The immersion plated substrates were later electroplated in aqueous medium, non aqueous media (alcohols), mixed aqueous (water/alcohols, water/ acetone),99% acetone and 37% formaldehyde containing hydrated cupric and stannous chlorides of 100 g/L each. The plating rate favours lower molecular weight alcohols, aqueous, mixed water/acetone and 37% formaldehyde media approximately in that order compared to akamu and 99% acetone. The addition of nitric, acetic and formic acids to plating solution also promotes plating rate.

BRONZE IMMERSION PLATING ON MILD STEEL IN CYANTDE-FREE SOLUTIONS