NANOMETRIC AI_2O_3 - ZrO-2 POWDERS PRODUCTION BY ARC PLASMA TREATMENT

摘要

Spherical nanometric Al_2O_3 -ZrO_2 powders have been prepared from commercial micrometric and irregular in shape ceramic oxides. A mixture of Sumitomo AES11SDC spray dried alumina and Magnesium Elektron S-grade zirconia (90/10 % in weight) was introduced during a few hours, with a rate of ～ 100 g/hour, through a lance and a screw feeder (under a flow of oxygen), inside the coupling zone of two plasma jets produced by a twin torch plasma system in a cylindrical furnace (arc current 200 to 400 A, voltage ～ 100 V; plasma forming gas: 20 NL/min of Ar at the anode, 10NL/min of Ar and 10 NL/min of He at the cathode). Powders collected inside the heat exchanger and on the bag filter have been analysed by TEM, laser granulometry and X-ray diffraction. The aggregates of small particles (from a few nm to ～100 nm) observed contain a and δ Al-2O_3 and monoclinic and tetragonal ZrO_2.