Preparation, thermal stability and sintering behavior of Ni/Al2O3 coated powders

Alumina-coated Ni powders were prepared by a heterogeneous precipitation method. The thermal stability of the coated powders was investigated by differential thermal and thermogravimetric analysis in air and argon, respectively. It was found that the alumina coating layers could effectively hinder the oxidation process of the Ni particles. The sintering behavior of the powders by hot pressing indicated that the coated powders exhibited a higher sinterability than ball-milled powders, and could be fully sintered at as low a temperature as 1350 °C. The microstructure of Al2O3/Ni composites from coated powders was different from that of convenient-processed composites.