고에너지 볼밀링 방법에 의해 얻어진 초미립 AlN 분말의 치밀화 및 미세구조

Abstract

In this study, a high energy ball milling process was employed in order to improve the densification of direct nitrided AlN powder. The densification behavior and the sintered microstructure of the milled AlN powder were investigated. Mixture of AlN powder doped with 5 wt.% Y2O3 as a sintering additive was pulverized and dispersed up to 50 min in a bead mill with very small ZrO2 beads. Ultrafine AlN powder with a particle size of 600 nm and a specific surface area of 9.54 m2/g was prepared after milling for 50 min. The milled powders were pressureless-sintered at 1700oC-1800oC for 4 h under N2 atmosphere. This powder showed excellent sinterability leading to full densification after sintering at 1700oC for 4 h. However, the sintered microstructure revealed that the fraction of yitttium aluminate increased with milling time and sintering temperature and the newly-secondary phase of ZrN was observed due to the reaction of AlN with the ZrO2 impurity.