碳化硅基复相陶瓷的高温氧化及其对强度的影晌

THE OXIDATION OF SiC-MATRIX MULTIPHASE CERAMICS AT HIGH TEMPERATURE AND ITS EFFECT ON STRENGTH

本文系统地研究了引入第二相非氧化物粒子TiC,TiB_2,ZrB_2和氧化物粒子Al_2O_3后SiC基复相陶瓷的氧化行为和规律,以及它对SiC基复相陶瓷强度的影响。实验结果发现,引入第二相非氧化物粒子后SiC基复相陶瓷的抗氧化性能大大降低,会在较低的温度下发生灾难性快速氧化,出现灾难性氧化的温度与引入的第二相非氧化物粒子的种类有关而与添加量无关,在出现灾难性氧化前的100～150℃,强度会发生大幅度下降现象;引入第二相氧化物粒子Al_2O_3的SiC基复相陶瓷,其抗氧化性不发生踢显变化,高温强度也不出现大幅度降低的现象;各种SiC基复相陶瓷的抗氧化能力次序为:SiC-Al_2O_3>SiC-TiC>SiC-TiB_2>SiC-ZrB_2。

The law and the behavior of the oxidation of SiC-matrix multiphase ceramics containing the non-oxide phase of TiC, TiB_2, ZrB_2and the oxide phase of Al_2O_3 respectively were studied. Their effect on bending strength of SiC-matrix multiphase ceramics was also studied. The experi- mental results indicate that the oxidation resistance of SiC-matrix multiphase ceramics containing the non-oxide phase decreases greatly, the disastrous rapid oxidation occurs at low temperature, which is related to the kinds of the non-oxide phase and not related to the amounts of the non-oxide phases, and the temperature at which strength decreases is 100～150℃ lower than that at which the disastrous oxidation occurs. The oxidation resistance of SiC-matrix multiphase ceramics containing the oxide phase of Al_2O_3 does not change significantly, the strength at high temperature does not decrease too. Degree of oxidation resistance for different SiC-matrix multiphase ceramics is of the following order:SiC-Al_2O_3>SiC-TiC>SiC-TiB_2>SiC-ZrB_2