Study on the use of CuSnTi brazing alloy for induction brazing of diamond grits surface-treated by direct current plasma chemical vapor deposition

•DC-PCVD for deposition amorphous carbon film on diamond grits•The treated diamond grits were induction-brazed using CuSnTi alloy.•The treated diamond grits protruding from the filler alloy maintain good sharpness.•The film enhances bonding strength between the filler alloy and diamond grits.

Induction brazing of diamond grits surface-treated by direct current plasma chemical vapor deposition (DC-PCVD) on a steel substrate was carried out in an argon atmosphere. A CuSnTi brazing alloy (with an approximate melting temperature of 900 °C) was used for this purpose. The diamond edges were exposed out of the brazing alloy to retain their sharpness. Relatively fine titanium–carbon compounds were formed with uniform interspaces on the brazed diamond surface when immersed in the brazing alloy. The liquid brazing alloy filled the interspaces, leading to increased bonding strength between the brazing alloy and diamond grits. Boring tests on diamond core drills brazed with the treated diamond grits and untreated diamond grits showed that the percentages of whole grain fracture and of pullout from the matrix of the brazed treated-diamond grits became lower.