| The present thesis used thermal analyse, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) etc to study sintering behavior, microstructure, martensite phase transformation and mechanical properties of nanometer m-ZrO2 /Al2O3 composite system. Simultaneously, we have also observed the effect of the initial volume fraction changes of ZrO2 on sintering behavior, constraining stress of matrix, grain growing and ZrO2 phase transformation.The sintering behavior was studied for monophase Al2O3 and ZrO2 samples as well as composite samples with different initial volume fraction of ZrO2 using raw materials of 0.6 m Al2O3 powder and 60nm ZrO2 powder respectively in this thesis. The results of sintering curves indicated that the max densification rate of monophase ZrO2 sample was greater than the counterpart of monophase Al2O3, but the starting temperature of intermediate and last stages as well as the corresponding temperature of max densification rate were lower than the counterpart of monophase Al2O3. Moreover shrinkage ratios of both monophase samples were very closed. These results displayed that the sintering behaviors of nanometer powders was better than sub-micron powders. In m-ZrO2 /Al2O3 composite materials, the sintering behaviors of samples were mainly controlled by the phase whose volume fraction was in the majority. Comparing with the corresponding monophase samples, the sintering curves as well as the starting temperatures of intermediate and last stages and the corresponding temperature of max densification rate of composites moved to higher temperature range, but the max densification rate were lower. These conclusions demonstrated that the hetero-phase powder mixed in composites inhibited sintering of samples. Otherwise, comparing the sintering velocity of 2 C/min with that of 5 C/min, we found the difference of sintering velocity did not obviously affect sintering behavior.The result of density experiment manifested that the density of samples in which the volume fraction of A12O3 was in the majority was lower than that of monophase A12O3, while the volume fraction of ZrO2 was in the majority was higher than that of monophase Al2O3. This conclusion agreed well with the sintering behavior of samples. The grain growing of A12O3 and ZrO2 observed by SEM was corresponding to the analyses of sintering behavior. The mean grain size of monophase Al2O3 was 2.16 m, which was 3.5 times the size of Al2O3 powder. With the increasing of ZrO2 initial volume fraction, the grain size of Al2O3 in samples was decreasing. The mean grain size of A12O3 in the sample contained 80vol. %ZrO2 was 0.78um, which was 1.3 times the size of A12O3 powder. And with the increase of Al2O3 volume fraction, the grain size of ZrO2 in samples was decreasing. The mean grain size of ZrO2 in the sample contained 80vol. % ZrO2 was 0.24 m, which was 4 times the size of Zr02 powder; while the mean grain size of ZrO2 in the sample contained 20vol. %ZrO2 was 0.14um, which was 2.3 times the size of ZrO2 powder.On the other hand, the effect of AbOs volume fraction on ZrO2 phase transformation was observed by the differential thermal analysis (DTA). The result showed there was a thermal retardation in ZrO2 phase transformation temperature. With the increasing of AbOa volume fraction, both high and low martensite temperatures were decreasing in the rage of 60 C and 1 90 C respectively. The variation ranges of low martensite temperatures were obviously greater than that of high martensite temperatures. The difference was growing in temperature of thermal retardation due to phase transformation. The reason was different influences during temperature increasing and decreasing on the potential barriers due to structure reorganization needed to get over in ZrO2 phase transformation as the constraining stress of matrix increasing.The experimental results of mechanical properties manifested that the micro-hardness got down with the increasing of the initial volume fraction of ZrO2 because of y...
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