MgAlON陶瓷的合成热力学与相关性能

Synthesis Thermodynamics and Properties of MgAlON Ceramics

评估、计算了Mg-Al-O-N系的热力学性质,并绘制了热力学参数状态图.在此基础上,合成了MgAlON陶瓷.对所合成材料的显微结构、晶体特征、物理性能及其抗氧化性能等进行了试验测定.所合成的MgAlON经X射线衍射和透射电镜分析未发现杂相,高分辨电镜分析发现MgAlON晶界无玻璃相,晶粒间为直接结合.试验得出了一套MgAlON的X射线衍射的指标化结果.MgAlON的三点抗弯强度在室温至1723K温度内都很高.MgAlON氧化过程的表观反应活化能为260kJ/mol,表观扩散活化能为573kJ/mol.

The thermodynamic properties of Mg-Al-O-N system were evaluated and the phase stability diagram of MgAlON was established. Based on the thermodynamic analysis, MgAlON with different compositions was synthesized. The microstructures, crystalline characteristics, mechanical properties and oxidation resistance of the synthesized materials were experimentally measured and discussed. A standard diffraction file of MgAlON was suggested. X-ray diffraction and TEM analysis show that there is no other phase than MgAlON detected. HREM analysis of MgAlON indicates that there is no glass phase existed at the grain boundaries, the grains are bounded directly. Three-point bending strength of MgAlON keeps very high until 1723K. Oxidation experiments of MgAlON show that, the activation energies of oxidation during the chemical reaction rate controlling stage and that during the diffusion controlling stage are 260 kJ/mole and 573 kJ/mole, respectively.