Abstract:The catalytic activities of different substrate metals in Ni-B-SiC electroless composite bath was investigated by means of measuring stationary potentials,potential-time curves and EPMA.The mechanism of electroless plating taking place in the substrate metals at initial stage was investigated.Experimental results showed:(1)In addition to the stationary potential of the substrate metal and the temperature of the bath,the change of the sur- face state of metal,e.g.,its passivity,is one of the factors for deciding catalytic activity of a substrate metal.(2) the transition time is helpful in determines the degree of catalytic activity.(3)If the substrate metals possess catalytic activity,the coating rates of electroless plating are mostly equal.

Key words: Electroless pIating; substrate metals; stationary potential; catalytic activity; passivity