Sintering of partially stabilized zirconia by microwave heating using ZnO-MnO_2-Al_2O_3 plates in a domestic microwave oven - self-heating and microstructure of PSZ
Partially stabilized zirconia (PSZ) powders were fully densified by microwave heating using a domestic microwave oven. The pressed powder compacts of PSZ were sandwiched between two ZnO-MnO_2-Al_2O_3 (ZMA) ceramic plates acting as a pre-heater in the microwave oven and put in the oven. PSZ ceramics fabricated with the domestic microwave oven for 16 min exhibited a density of 5.7 g/cm~3 which is approximately equal to the density of bodies sintered at 1300-1350 °C for 4 h by the conventional furnace method. The average grain size of the samples obtained by this furnace method was larger than that of the sample sintered by a conventional heating process similar to microwave heating. The PSZ pellet pre-heated by the ZMA ceramics more easily absorbed the microwave energy and self-heated to a higher temperature. The achieved temperatures and the resulting densification depended strongly on the diameter of the PSZ pellet. High densities over 5.5 g/cm~3 and elevated temperatures over 1200 °C were achieved for the specimens with diameters over 20 mm.
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