SOME OBSERVATIONS ON THE WETTING AND BONDING OF NITRIDE CERAMICS

Several series of experiments have been conducted to gain information about the wettability of AlN, BN, Si3N4 and two sialon ceramics by potential braze materials. It was possible to achieve wetting of all five ceramics using aluminium, copper-titanium alloys, and a Ag-28Cu-2Ti alloy. Wetting by aluminium and the Ag-28Cu-2Ti alloy was usually good. Both wetting and non-wetting alloys containing titanium reacted to form TiN and it is argued that the achievement of wettability is associated with a certain degree of hypostoichiometry. While aluminium should also have reacted, no clear evidence was obtained. In supplementary experiments it was found that bonds formed by brazing with aluminium at 1000 °C could have shear strengths as great as 60MPa. Although the experimental work was preliminary in nature, it suggested that good brazing systems could be developed. © 1990 Chapman and Hall Ltd.