Laser brazing of diamond grits using a Cu-15Ti-10Sn brazing alloy

Abstract

Brazing of diamond grits onto a steel substrate, using a Cu-Ti-Sn brazing alloy, was carried out via laser brazing in an argon atmosphere. The laser power was maintained at either 400, 450, or 500 W, while the laser irradiation time was 10 seconds. For a brazed layer of about 7 mm in diameter and 90 μm in thickness, a power input of 450 W was found to yield the optimal result. Due to the short irradiation time at high temperatures, discrete TiC grains of about 100 nm in size developed, instead of a continuous TiC layer formed at higher and longer process conditions, on the diamond surface. These TiC grains still effectively reduced the stress associated with the mismatch between the diamond grit and Cu in the aspects of lattice constant and thermal expansion coefficient. Accordingly, only a low percentage (about 5%) of diamond grits was pulled out of the brazed layer after a grinding test.