成型工艺对莫来石增强磷酸铬铝复相陶瓷的性能影响

Effect of Molding Process on the Properties of Mullite Reinforced Aluminum Chromium Phosphates Composite Ceramics

以磷酸铬铝、氢氧化铝、熔融石英粉为原料,采用干压成型、注凝成型与等静压成型制备原位莫来石增强磷酸铬铝复相陶瓷,并进行对比研究。研究结果表明,等静压成型制备复相陶瓷的机械性能均优于干压成型和注凝成型制备的复相陶瓷,且复相陶瓷的介电常数比干压成型和注凝成型的复相陶瓷高。干压成型制备的复相陶瓷不够致密均匀,气孔较多;注凝成型和等静压成型制备的复相陶瓷结构均匀致密且气孔较少,复相陶瓷的晶粒发育较完善,短棒状莫来石晶粒和球状磷酸铬铝晶粒分布均匀且清晰可见。通过制品的性能参数和显微结构的比较,等静压成型制备的素坯结构均匀致密,强度高,收缩率小,等静压成型制备的莫来石增强磷酸铬铝复相陶瓷综合性能最优,复相陶瓷的密度、介电常数、维氏硬度及弯曲强度分别为2.85 g·cm^(-3)、4.76、6.2 Gpa、151 Mpa。

In-situ mullite reinforced aluminum chromium phosphates composite ceramics are prepared by the solid-state, Gelcasting and cold isostatic pressing respectively with aluminum phosphates, fused silica and aluminum hydroxide and a contraste study of these preparing methods is conducted. The results indicate that the mechanical properties of composite ceramics prepared by clod isostatic pressing are better than those by the solid-state and Gelcasting, and that the relative dielectric constant of composite ceramics prepared by the solid-state and Gelcasting is lower than those by clod isostatic pressing. The composite ceramics prepared by the solid-state have relatively more pores with weak dense and uniform. The structure of composite ceramics prepared by Gelcasting and cold isostatic pressing is fully uniform and dense with fewer pores, in which the uniform distribution of short columnar-shape mullite and spherical aluminum chromium phosphates are clearly visible and fully uniform. Compared with the performance parameters and microstructure of products, the structure of green bodies prepared by cold isostatic pressing is fully uniform and dense, the linear shrinkage of green bodies is lower and the flexural strength of green bodies is higher than those prepared by the solid-state and Gelcasting, the comprehensive performance of in-situ mullite reinforced aluminum chromium phosphates composite ceramics by cold isostatic pressing is best, whose density, relative dielectric constant, Vickers hardness, and flexnral strength are respectively 2.85g·cm-3, 4.76, 6.2GPa and 151MPa.