Microstructure and thermal decomposition property of Ni-P/Cr2N composite powder by electroless plating

Abstract

Cr2N is the most promising blowing agent for the preparation of steel foam using melt foaming method. In this work, to obtain a blowing agent with suitable density and gas decomposition characteristics for steel melt foaming, Ni-P/Cr2N composite powder was prepared by electroless plating. The surface morphology, phase, coating thickness, density and decomposition characteristics of Ni-P/Cr2N composite powder were analyzed. The results indicate that the surface of Ni-P/Cr2N composite coating powder is covered by the high nickel and low phosphorus layer which has a dense and uniform cell structure. The decomposition rate of the Ni-P/Cr2N composite powder is 7.46 mW/mg slower than that of the uncoated Cr2N powder at 1107.4 °C. When the plating time is 30 min, the thickness of Ni-P layer reaches 2.86 μm, the density of the Ni-P/Cr2N composite powder is 7.45 g/cm3, and maximal decomposition rate temperature reaches 1500 °C. These findings suggested that Ni-P/Cr2N composite powder meets the requirements of decomposition temperature and density of the blowing agent used to produce steel foam with a uniform pore structure by the melt foaming method.