Effect of Ti-coating on cool welding of large-size diamond grits

To solve the problem of severe processing conditions in the cool welding of uncoated diamond grits, the effect of Ti coating around diamond grits on the cool welding of the diamond grits was studied. The Ti-coated diamond grits welded by cool welding maintained sharp edges and corners because the diamond grits were protected from heat damage by the Ti coating. The Ti coating also promoted seamless bonding between the cool welding layer and diamond grits and improved the holding strength of welding material toward the diamond grits. The surface compressive stress for uncoated diamond grits was about 0.15 GPa and that for Ti-coated diamond grits was about 0.13 GPa. The surface compressive stresses between them did not significantly differ from each other. However, the full width at half maximum (FWHM) of Raman spectra of Ti-coated diamond grits was 6.1 cm-1 smaller than that of uncoated diamond grits, indicating that the Ti coating can stabilize the diamond microstructure. The grinding test indicated that the processing efficiency of Ti-coated diamond grits was relatively high, and the usability was relatively stable. The study can further fulfill theoretical demonstration for preferable replacing of damaged grits of brazed diamond tools with large-size diamond grits.