The preparation and research of alumina powder by the electrical discharge machining method

Ultrafine alumina powder was prepared through the method of electric spark plasma ablation and a study was carried out by means of X-ray diffraction, scanning electron microscopy, energy spectrum analysis and laser particle size analysis. The following conclusions were drawn: the alumina can be prepared by spark, which gives an upper layer powder and lower layer coarse powder. Upper powder is mainly gamma-alumina and alpha-alumina, and a small portion of residual aluminium, and the particle size is a few tenths of a micrometre. Lower coarse powder is mainly two kinds of alpha-alumina and more residual aluminium, having a particle size of several tens of micrometres. Upper powder will be reunited, because of the presence of aluminium hydroxide powder that makes the alumina particles stick together. The thickness of the rod, pulse width and pulse interval may affect particle size.