Abstract
Laboratory studies have been made on chromium plating from the low concentration bath containing CrO3 50g/l, H2SO4 0.5g/l, and Na2SiF6 0.5g/l. Compared with the deposits from the conventional high concentration bath, the chromium deposits from the low concentration bath were almost similar in respect of bright area, throwing power, covering power, current efficiency, hardness, crack and corrosion resistance etc. Also, the industrialization of chromium plating from the low concentration bath has been made successfully in a full automatic batchtyped and a handtyped plating process in a plating factory. In the fomer process, Sargent bath constituents could be reduced to CrO3 100g/l, H2SO4 1g/l by stopping replenishment of CrO3 and H2SO4. In the latter case, the bath was diluted with water to the above mentioned low concentration. Consequently, the amounts of CrO3 supplied, rinse water, chemicals for effluent treatments, and sludge produced were remarkably decreased with lowering concentration of CrO3 in the chromium plating bath.
