Cdiamond–(WC–Co)–ZrO2 Composite Materials with Improved Mechanical and Adhesive Properties

The structure, mechanical properties (hardness H and elastic modulus E), evaluation parameters for determining the resistance of the material to elastic (H/E) and plastic (H³/E²) deformations, resistance 1/(E²/H) to abrasive wear, and the ability of the hard alloy matrix to hold diamond grains from their precipitation in the 25 wt % C_diamond‒70.5 wt % WC‒4.5 wt % Co composite diamond-containing materials (CDMs) with different contents of ZrO₂ (in the range from 0 to 10 wt %), which are formed by the spark plasma sintering (SPS) method in the temperature range of 20‒1350°C under a pressure of 30 MPa for 3 min. The initial CDMs have a coarse grained structure with weak adhesion of diamond grains to the hard alloy matrix and are characterized by low values of H/E, H³/E², and 1/(E²H), which is the reason for the premature loss of diamond grains. The presence of ZrO₂ in the composition of CDMs interferes with the processes of Oswald ripening and acts as a growth inhibitor that ensures the reduction of WC grains, the formation of strong adhesion of diamond grains to the matrix, and a substantial increase in the H/E, H³/E², and 1/(E²H) parameters. As a result, the ability of the matrix to reliably hold diamond grains from premature loss during the CDMs operation increases. It is shown that the addition of zirconium dioxide in the amount of 10 wt % to the composition of the 25 wt % C_diamond‒70.5 wt % WC‒4.5 wt % Co composite leads to increases in the H/E parameter from 0.043 to 0.057, in the H³/E² parameter from 0.05 to 0.075 GPa, and in the 1/(E²H) parameter from 0.75 × 10^–7 to 2.75 × 10^–7 GPa^–3. Moreover, signs of strong adhesion between the diamond grains and the carbide matrix in the CDMs samples are revealed.