Microwave Brazing of Polycrystalline Diamond Onto Drill Bits

A microwave-heating technique has been developed for making a braze joint (1) between a tungsten carbide support and a surface layer of polycrystalline diamond or, alternatively, (2) between a tungsten carbide support and a relatively thin tungsten carbide backing layer with polycrystalline diamond on its working surface. The technique would be used to fabricate diamond-covered cutting tool bits. Such bits could be used, for example, to drill geothermal wells and would be improved versions of some of the diamond-covered bits now used to drill oil and gas wells. Whereas the braze joints of the oil-and-gas-well versions become weakened at temperatures ≥ 700°C, the braze joints of the improved drill bits would be designed to withstand hard-rock-drilling temperatures up to 900 °C.