Structure Transformations and Property of Electroless Ni-B Coating
WT5BZ]A Ni B coating is prepared by EP with potassium borohydride reducing agent The as plating microstructure of coating is confirmed to be a mixture of amorphous and supersaturated solid solution with XRD analysis The micro hardness is up to HV1300 after heat treatment The transformation process of the coating microstructure depends on heat treatment temperature, and 350℃ is the critical temperature of microstructure transformation It is found that Ni 2B is formed during this transformation process The factors which influence on hardness of coating are evolution of stress, dissolution of B and formation of Ni 3B and Ni 2B And the formation of Ni 2B is the key factor The peaks of micro hardness curves vary with heat treatment temperatures, and tend to shorten heat treatment time with higher temperature The transformation process becomes more complex when the heat treatment temperature accesses crystallizing temperature