Dissimilar laser brazing of boron nitride ceramics and cemented carbide has been investigated by using silver-copper-titanium braze alloys with different titanium contents of up to 2.80 mass%; efficient bond strength was achieved using brazes with more than 1.25 mass% of titanium. The contact angle between hexagonal boron nitride ceramics and the molten braze, which was measured by the sessile drop method at 1123 K, decreased to less than 30 when the Ti content was over 0.41 mass%. The difference in the wetting property determined by laser brazing method and that by sessile drop method is attributed to the difference in the heating process of the two methods. Structural analysis of the interface between the boron nitride ceramics and the braze was carried out by electron probe micro-analysis (EPMA).

Dissimilar laser brazing of boron nitride ceramics and cemented carbide has been investigated by using silver copper titanium braze alloys with different titanium contents of up to 2.80 mass; efficient bond strength was achieved using brazes with more than 1.25 mass of titanium. The contact angle between hexagonal boron nitride ceramics and the molten braze, which was measured by the sessile drop method at 1123 K, decreased to less than 30°when the Ti content was over 0.41 mass. The difference in the wetting property determined by laser brazing method and that by sessile drop method is attributed to the difference in the heating process of the two methods. Structural analysis of the interface between the boron nitride ceramics and the braze was carried out by electron probe micro analysis (EPMA). (Received May 24, 2010; Accepted June 30, 2010) Keywords: laser brazing, boron nitride ceramics, cemented carbides, silver copper titanium alloy braze, composition dependence, contact angle