The thermal shock fatigue behaviors of pure hot-pressed alumina and 30 wt.% TiC/Al2O3 composites were studied. The effect of TiC and Al2O3 starting particle size on the mechanical properties of the composites was disc...The thermal shock fatigue behaviors of pure hot-pressed alumina and 30 wt.% TiC/Al2O3 composites were studied. The effect of TiC and Al2O3 starting particle size on the mechanical properties of the composites was discussed. Indentation-quench test was conducted to evaluate the effect of thermal fatigue temperature difference （ΔT） and number of thermal cycles （Ⅳ） on fatigue crack growth （Δa）. The mechanical properties and thermal fatigue resistance of TiC/Al203 composites are remarkably improved by the addition of TiC. The thermal shock fatigue of monolithic alumina and TiC/Al2O3 composites is due to a ＂true＂ cycling effect （thermal fatigue）. Crack deflection and bridging are the predominant reasons for the improvement of thermal shock fatigue resistance of the composites.展开更多
Dense Y-TZP ceramics and Y-TZP/Al_2O_3 composite ceramics are prepared successfully by microwave sintering using rectangle single mode (TE_(10n)) applicator. The heating characteristcs by microwave of the materials ar...Dense Y-TZP ceramics and Y-TZP/Al_2O_3 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% Al_2O_3-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.展开更多
文摘The thermal shock fatigue behaviors of pure hot-pressed alumina and 30 wt.% TiC/Al2O3 composites were studied. The effect of TiC and Al2O3 starting particle size on the mechanical properties of the composites was discussed. Indentation-quench test was conducted to evaluate the effect of thermal fatigue temperature difference （ΔT） and number of thermal cycles （Ⅳ） on fatigue crack growth （Δa）. The mechanical properties and thermal fatigue resistance of TiC/Al203 composites are remarkably improved by the addition of TiC. The thermal shock fatigue of monolithic alumina and TiC/Al2O3 composites is due to a ＂true＂ cycling effect （thermal fatigue）. Crack deflection and bridging are the predominant reasons for the improvement of thermal shock fatigue resistance of the composites.
文摘Dense Y-TZP ceramics and Y-TZP/Al_2O_3 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% Al_2O_3-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.
