Joint Gap and Joint Strength of Cemented Carbide Brazed with Silver Filler Metal

Abstract

PCD Tools have a high heat resistance and a high abrasion resistance. PCD tools are made by brazing a cutting blank and a cemented carbide base. However, the strength of the brazing is varied. In this paper, joint strength of specimens of cemented carbide brazed with silver filler metal was investigated through tensile tests and Cantilever beam bending tests. The tests revealed that the strength of the joints decreases as the joint gap is narrower. Therefore two methods to control the gap of the brazing joint were developed. One is a chamfering method where the chamfering forms the gap. The other is a powder mixture method in which metal powder is mixed with brazing filler metal as a spacer. The average of joint strength increased approximately 1.5 times when the brazing gap was more than 25 μm to around 40 μm by 75 μm Ni powder spacer. The strength of the Cantilever beam bending was discussed by the finite element analysis.