Preparation of alumina and alumina-silica powders by wire explosion resulting from electric discharge

• Published in: Journal of materials science Vol. 30; no. 5; pp. 1240 - 1244
• Main Authors: UMAKOSHI, M, YOSHITOMI, T, KATO, A
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-03-1995
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Powders; Scanning electron microscopy; Aluminium Oxides; Particle size; Transmission electron microscopy; Morphology; Silicon Oxides; Alumina; X ray diffraction; Silica; Fine powder
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/bf00356125

Wires of Al and Al-Si alloys containing 5.2 and 12.1 wt% Si were exploded in air by electric discharge, and the properties of the powders obtained were examined. The powders consisted of large particles and very fine spherical ones, which were formed from the metallic droplets and vapours, respectively, and were mostly oxidised. The large particles decreased with an increase in the charged energy. Although the particle size distribution was broad, the average particle sizes were small increasing from 0.7 to 1.3 microns with an increase in charged energy. These gamma-Al2O3 powders, an amorphous Al2O3-SiO2 compound and a small amount of metal were identified. The amorphous phase crystallised to mullite in the temperature range 1153-1243 K, and the crystallisation temperature fell with an increase in the charged energy because the amount of fine particles formed from the vapours increased. 11 refs.