Characteristics of Machining Damage of Alumina Ceramics

Abstract

Machining damage was examined on alumina ceramics with various grain sizes, which were prepared using a dry-pressing method with spray-dried granules, followed by sintering at 1570°C for 2-27 hours. The grain sizes of the sintered bodies were 3-9 μm. After machining, the specimens were placed in an alcohol solution of fluorescent dye and then dried. The fracture strength was measured by 4 point bending. The fracture surface was observed using a confocal scanning laser fluorescence microscope. The fluorescent dye in the specimen shows the machining flaw directly. The machining flaw was spread almost uniformly in the specimen with small grain size. The fracture resulted from the machining flaws. The fracture strength was strongly dependant on the extent of the machining damage.