ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract It is well known that the existence of oxygen in the sintering of aluminium nitride (AIN) causes the degradation of thermal conductivity. To clarify the role of the oxygen, the effect of Al2O3 addition on the phase reaction of the AIN-Y2O3 system at high temperatures of 1900 and 1950°C was investigated. In the AIN-Al2O3 system, γ-AION and 27R polytypoid were formed at 1900 and 1950°C, respectively, and the ratio of each crystal increased with increasing Al2O3 content. The resultant phase was found to be in agreement with the phase diagram given by McCauley and Corbin. In the AIN-Y2O3 system, YAM phase or YAM plus unreacted Y2O3 were identified. Phase reaction in the AIN-Al2O3-2Y2O3 system was quite different from that of the AIN-Al2O3 system: namely, γ-AION and 27R coexisted even at 1950°C, which is inconsistent with McCauley and Corbin's diagram. It was confirmed by the dilatometric method and phase reaction data using some couples, that Al2O3 strongly affected the phase reaction in the AIN-Y2O3 system, indicating that the shrinkage of the Al2O3-doped specimen was initiated at somewhat lower temperatures. The grain morphology depended on the phase changes shown above, in which AIN and γ-AION were granular, and 27R polytypoid was plate-like.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00357870
