Preparation and sintering of Ni-coated Si3N4 composite powders

Ni-coated Si3N4 composite powders were prepared successfully via electroless plating by using sodium hypophosphate (NaH2PO2) as reducing agent. The Ni coating layers contained 12 wt.% phosphor and were dominantly amorphous with a thickness of 20-60 nm. The sintering properties of Ni-Si3N4 composite were improved by adding Mo2C into Si3N4 powders, in which Mo2C formed liquid to improve the α-β transformation of Si3N4, and Mo2C converted into MoSi2 after sintering. The composite powders were densified by hot-pressing at 1600 °C. The final crystal phases of the sintered samples were Si3N4, Ni and MoSi2.