Microwave sintering of zirconia-toughened alumina composites

摘要

The feasibility of firing ziconia-alumina composites has been demonstrated. Techniques have been developed whereby virtually any composition of ZTA can be fired in 2.45- and 28-GHz microwave fields. Comparing data from conventional and microwave firing shows that the sintering temperature can be as much as 500(degree)C lower for the microwave case. A reduction in sintering temperature, as suspected, appears to result in a significant decrease in the grain size in the microstructure. Apparently, the path of microstructural change is altered so that densification can proceed with little coarsening as an interfering mechanism. The microwave effect appears to be a function of frequency. Our results give some indication of why the microwave effect was not seen earlier at 2.45 GHz. Technological problems associated with producing uniform fields interfere and in this case mask the microwave effect. With larger cavities and perhaps more clever insulation schemes, it may be possible to reproduce the results in 2.45 GHz that are seemingly so easily achieved at higher frequency. 9 refs., 9 figs.