INFLUENCE OF POWDER CHARACTERISTICS ON SINTERING PROCESS AND THERMAL-CONDUCTIVITY OF ALUMINUM NITRIDE CERAMICS

The sinterability and thermal conductivity of Y2O3 doped AIN powders w ith diverse specific surface areas (42-2.9 m(2)g(-1)) and oxygen conte nts (0.2-2 mass%) were evaluated. It was found that sintering of fine powders induces the densification at lower processing temperatures, an d for raw AlN powders with specific surface area larger than 20 m(2)g( -1) and oxygen content higher than 1.1 mass%, densified specimens were obtained by sintering at 1650 degrees C for 4h. However, the resultan t thermal conductivity of AlN specimens fabricated from fine powders w as extremely lower than the theoretical thermal conductivity of AlN, a t a level of 80 Wm(-1)K(-1). The deterioration of the thermal conducti vity has been attributed to the, agglomeration of primary particles, a nd to subsequent formation of oxygen-related defect in grown AlN grain s occurring at an early stage of sintering.