Al_2Mo_(3-x)W_xO_(12)的合成及热膨胀特性的研究

The Synthesis and Thermal Expansion of Al_2Mo_(3-x)W_xO_(12)

使用共沉淀法合成了完全固溶的Al2Mo3-xWxO12系列粉体材料, 用热机械分析(TMA)压缩法测定其热膨胀系数,发现Al2Mo3-xWxO12的单斜-正交转变温度随x增加而下降;通过调整材料的组成,可以控制材料的热膨胀系数,并有望在此类材料中获得近零或负热膨胀材料。但是由于其结构的各向异性,多晶陶瓷内部存在的微裂纹使热膨胀曲线出现较大的滞后环。

Near zero and negative thermal expansion materials have a number of important potential applications including circuit boards, optical substrates, dental restorations and so on. This article describes the synthesis of, Al2Mo3-xWxO12 powder a co-precipitation method. The average thermal expansion coefficients of Al2Mo3-xWxO12 from 20degreesC to 840degreesC and their thermal expansion curves during heating (20degreesCsimilar to850degreesC) and cooling (850degreesCsimilar to200degreesC) were measured by the thermo-mechanic analysis (TMA) method. The results indicate that the thermal expansion coefficient of Al2Mo3-xWxO12 can be adjusted to near zero by changing the composition. The TMA results also revealed that the monoclinic-to-orthorhombic phase transition temperature of decreases with increasing W content. The thermal expansion curves are hysteretic due to micro-cracks resulting from structural anisotropy.