Research on Pb-free Electroless Ni Plating for Pistons of General-purpose Engines
Ni-P-B plating applied to the piston of a general-purpose engine with an aluminum alloy cylinder contains some thousands ppm of Pb, which is used as the treating liquid stabilizer, in its plating. But, Pb is considered an environmental hazardous and it is necessary to reduce its amount in the plating. Our previous researches, however, reveal that Pb plays a major role in wear and seizure resistance. In order to obtain the sliding properties equivalent to Ni-P-B plating that contains Pb, therefore, it is necessary to review the composition of Ni-P-B plating. In this research, therefore, we specifically focus on the plating hardness of Ni-2%P plating subject to the temperature environment in which the piston operates, and discuss whether the same sliding effects as that of the Pb containing Ni-P-B plating is obtainable by restraining the hardness decrease.