Strength evaluation of carbon/metal joint

Evaluations of microstructure, hardness and strengths have been performed on the carbon/metal joint by brazing. Micro-structure of the joint was observed by scanning electron microscope (SEM). Strengths were measured by using a dynamic ultra-microhardness tester and by four-point bending method. As a result, the following conclusions were drawn: (1) Enough intrusion of the brazing metals to the carbon material was observed on each joint by SEM. (2) It was made clear by means of the dynamic ultra-microhardness tests that the hardness values of copper and carbon material portions in the position of 0.05mm from the center of the brazing part were higher than those of other portions. (3) In the four point bending tests, the carbon material portions were broken in all joints and the strength was near that of carbon material itself. (author)