Rapid microwave sintering of Y2O3 nanopowder samples has been investigated. Using a 24 GHz / 6 kW gyrotron system for microwave processing of materials, the compacted powder samples were heated at rates in the range 10...200 °C/min to maximum temperatures 1400... 1700 °C with zero hold time. At higher heating rates a sharp increase in the material's effective conductivity has been observed, which is similar to the flash sintering effect. Maximum densities of the sintered Y2O3 samples, above 98 %, have been obtained with a heating rate of 100 °C/min and maximum temperatures 1600...1700 °C. The duration of the high-temperature stage of sintering was about 8 min and the microwave power absorbed in the samples, per unit volume, was about 40 W/cm~3.
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