Effect of Milling Media Purity on Pulse Electric Current Sintering and Strength of Aluina Ceramics Prepared from Transition Alumina Powder

摘要

Alumina ceramics were densified at sintering temperatures of 1250-1550 deg C by pulse electric current singering (PECS) using transition alumina powder of mixed phases of gamma-and X-alumina prepared from polyhydroxoaluminum (PHA) gel.The starting high-purity powder (HP) was obtained by grinding the alumina powder with a planetary ball mill using a high-purity alumina (purity:99.9%) pot and balls to prevent contamination derived from the abrasion powder worn during the milling.The HP thu obtained realized full densification at sintering tempratures 50-100 deg C lower than those of the corresponding lower-purity powder (L),which was obtained by grinding with a planetary ball mill using a 93%-pure alumina pot and 99.9%0-pure alumina balls.The HP could also provide alumina ceramics with higher bending strengths (approximately 860 MPa) than those obtained using LP.