Nanoengineered Polycrystalline Diamond Composites with Advanced Wear Resistance and Thermal Stability.

Fluorinated grains of micrometer size diamonds overcoated with nanodiamond particles were used as a feedstock for high-pressure, high-temperature synthesis of new polycrystalline diamond composites (PDCs). Such a nanoengineering approach for exploring the interfacial chemistry of diamonds has been implemented in two methods: (i) infiltration of Co from the WC-Co layer into a fluorinated diamond layer with added Al and (ii) sintering of fluorinated micro- and nanosize diamond homogeneous mixtures with added Al and Co. We found that unlike commercial PDCs made with a metallic Co binder for drilling tools, the binding phase in new composites comprises only intermetallic compound AlCo or ternary carbide AlCoC. As a result, composites made from homogeneous mixtures showed greater promise for improving the thermal stability, while the two-layer experimental composites during granite turning tests have demonstrated >2 times higher wear resistance than leached commercial PDCs.