Improvement of thermal stability of diamond by adding Ti powder during sintering of diamond/borosilicate glass composites

Oxidization of diamond in the sintering process of diamond/glass composites results in thermal degradation of diamond and uncontrolled expansion of the bulk composites with many irregular pores, causing low bending strength of the composites. In this paper, Ti powder was used as oxygen getter due to its excellent affinity with oxygen. The results showed the diamond grits got good protection from oxidation during sintering due to the prior reaction of Ti powder with oxygen. As a result, expansion phenomenon was inhibited and bending strength was improved for the composites due to the Ti additives. TiO2, as oxidization product of Ti, could enter into the glass network. The maximum bending strength and minimum volume expansion values were obtained for the composites with 6 wt.% Ti powder. This content resulted in a decrease of volume expansion from 22.78% to −25.0%, and an increase in bending strength from 28.49 MPa to 100.54 MPa.