EFFECT OF ULTRAFINE ALN AL AND EU2O3 POWD ER ADDITION ON SINTERING CHARACTERISTICS AND THERMAL-DIFFUSIVITY OF AIN/

The composite ultrafine powder AlN/Al with an average size of 300 nm w as synthesized by are-plasma method. This powder was added up to 15 ma ss% into the two kinds of commercial AN powders prepared by the direct nitridation of Al and the carbon reduction nitriding of Al2O3. The mi xed powders with the sintering aid Eu2O3 were sintered in the temperat ure range from 1923 to 2123 K in a flow of N-2 gas and their density a nd thermal diffusivity were measured at 300 K. The composite ultrafine powder AlN/Al promotes the sintering of the two kinds of ALN powders. A sintered compact of AN with the theoretical density was obtained at 1973 K by adjusting the amounts of Eu2O3 and composite ultrafine powd er AlN/Al. The thermal diffusivity of the sintered sample increases wi th increasing the amount of the composite ultrafine powder AlN/Al if t he sintering temperature is lower than 2073 K and the amount of Eu2O3 is less than 3 mass%. Otherwise it decreases with adding the composite ultrafine powder. Compared with the case used Y2O3 as the sintering a id, the effect for the composite ultrafine powder to promote the sinte ring of AlN is larger, but the effect for it to raise the thermal diff usivity of AN is smaller when the sintering aid Eu2O3 is used.