Heating and sintering characteristics of Y-TZP and Y-TZP/Al₂O₃ by microwave

Dense Y-TZP ceramics and Y-TZP/Al₂O₃ composite ceramics are prepared successfully by microwave sintering using rectangle single mode (TE_10n) applicator. The heating characteristcs by microwave of the materials are related to the sample compositions. Higher Y-TZP content leads to a higher heating-up rate and a shorter time period needed for heating-up. The input power, short circuit plug position and the opening size of adjustable coupling iris are adjusted timely to maintain the resonance and the optimum coupling condition, and therefore a certain heating-up rate and final stable sintering temperature could be achieved. Relative densities above 98% TD are obtained for Y-TZP and 20 Vol% Al₂O₃-Y-TZP composite ceramics, with their grain sizes of about 0.4 and 1.0 μm, respectively. It is also found that the sample center can be over-sintered when the temperature is too high since a higher temperature at the sample center is usually reached than that at the surface.