Low-temperature sintering behavior of aluminum nitride ceramics with added copper oxide or copper

Abstract

The low-temperature sintering behavior of AlN was investigated through a conventional method. CaF 2 , CuO and Cu were selected as additives based on their low melting points. When sintered at 1600 o C for 8 h in N 2 atmosphere, a sample density > 98% was obtained. The X-ray data indicated that eutectic reactions below 1200 o C were found. Therefore, the current systems have lower liquid formation temperatures than other systems. The liquid phase showed high dihedral angles at triple grain junctions, indicating that the liquid had poor wettability on the grain surfaces. Eventually, the liquid was likely to vaporize due to the unfavorable wetting condition. As a result, a microstructure with clean grain boundaries was obtained, resulting in higher contiguity between grains. From EDS analysis, oxygen impurity seems to be well removed in AlN lattice. Therefore, it is believed that the current systems are beneficial for reducing sintering temperature and improving oxygen removal.