Xg. Li et al., EFFECT OF ULTRAFINE (ALN AL) AND Y2O3 POW DER ADDITION ON SINTERING CHARACTERISTICS AND THERMAL-DIFFUSIVITY OF ALN/, Nippon Kinzoku Gakkaishi, 60(2), 1996, pp. 128-134
Ultrafine powder AlN/Al with an average size of 300 nm was synthesized
by an are-plasma method. This powder was added up to 20 mass% into tw
o kinds of commercial AlN powders prepared by direct nitridation of Al
and carbothermal reaction of Al2O3. The samples were sintered at a te
mperature range from 1973 to 2123 K in a flow of N-2 gas with the help
of sintering aid Y2O3 and their density and thermal conductivity were
measured at 300 K. The ultrafine powder AlN/Al has a noticeable effec
t to reduce the sintering temperature and enhance the thermal diffusiv
ity of the two hinds of AlN powders. This effect is more significant i
n the direct nitrided powder than that in the reduced powder. The sint
ered AlN compact with high density and high thermal diffusivity can be
obtained at temperature lower than 2123 K with the aid of the ultrafi
ne powder AlN\Al. Mechanism of this effect can be elucidated by the fa
ct that the ultrafine powder AlN/Al has a large specific surface area
and react easily with Y2O3 at low temperature where the commercial AlN
powders can not. The effect of the ultrafine powder AlN\Al changes wi
th the sintering temperature and Y2O3 content and the good effect of t
he ultrafine powder AlN/Al is observed when the sintering temperature
is lower than 2123 K and Y2O3 is less than 8 mass%.