Advanced Low-Stress Bonding of Thermally Stable Polycrystalline Diamond Cutters to Tungsten Carbide Substrates

40144 Science Research Laboratory This project will develop a thermally stable polycrystalline diamond cutter than can withstand the higher impact forces and higher cutting temperatures encountered in drilling harder formations with shear bits. A high energy electron beam (HEEB) will be used to braze polycrystalline diamond films to tungsten carbide-cobalt surfaces. This technique is expected to minimize degradation of the two surfaces and eliminate stresses caused by the mismatch in the coefficients of thermal expansion. Phase I will develop the HEEB brazing system, perform preliminary experiments to demonstrate low-stress joining, and determine joint properties. Phase II will be concerned with process optimization, fabrication of sufficient quantities of cutters for laboratory and field use, and qualification of the cutter by bit manufacturers . Anticipated Results/Potential Commercial Applications as described by the awardee: Application of this technology will allow the use of shear bits in harder formations than hitherto possible. The advanced cutter technology will also be applied to production of advanced diamond bearings for mud motors and gauge protectors for stabilizers and roller-cone bits.