Enhanced mechanical and thermal properties of AlN ceramics via a chemical precipitation process
Guanglin Nie, Pengfei Sheng, Yehua Li, Fei Zuo, Yiwang Bao, Shanghua Wu
Abstract
Abstract A uniform dispersion of sintering additives is crucial to improve the thermal and mechanical properties of AlN ceramics. In this study, the Y 2 O 3 ‐coated AlN composite powder was successfully prepared by the chemical precipitation (CP) process, thereby improving the homogenization of Y 2 O 3 in AlN green compacts. The precipitation coating behavior of Y 2 O 3 precursor was investigated by FTIR and TG‐DSC, and the corresponding reaction equation was proposed. The results of TEM, XRD, and XPS for the CP processed AlN powder indicated that a uniform amorphous Y 2 O 3 layer was fully wrapped on the surface of AlN powder. The microstructures and phases of the sintered AlN samples prepared via the CP and conventional ball‐milling (BM) processes, respectively, were compared. The CP process can result in decreasing oxygen content in AlN grains, facilitating the formation of the desirable isolated second phases, and strengthening the grain and grain boundary of AlN ceramic. As a result, the thermal conductivity, bending strength and fracture toughness of the CP processed AlN ceramic are 9.43%, 10.56%, and 18.50% higher than those of the BM processed sample, respectively, illustrating the CP process is a pretty effective way to simultaneously improve the thermal and mechanical properties of AlN ceramics.