The Role of Diamond Surface and Intrinsic Contaminates on Sintering of PDC
by Dr. Michael Vail
High pressure/high temperature sintering of polycrystalline diamond compacts (PDC) is sensitive to impurities in the diamond feedstock, both surface and intrinsic. Diamond powders subjected to the ultra-high pressure sintering environment break down and fracture, exposing new surface area. Thus intrinsic contaminants are exposed as surface contaminants to the sintering environment as a function of pressure. The surface contaminants of three diamond feedstocks were measured after exposing the material to increasingly higher pressure up to the diamond stable region. Two of the samples exhibited a three fold increase in the cumulative addition of contaminant material as pressure was increased. The third sample added very little contaminants to the sintering environment. The control of contamination material presented to the in-situ reaction environment may be fundamental in maintaining a reliable production system for sensitive diamond sintering processes.
After the pioneering development and marketing of PDC cutters by General Electric (GE) in the 1970s, numerous companies initiated their own PDC cutter and drill-bit product lines. Since that time, Sandia National Laboratories has supported the drag-cutter and bit industries by conducting landmark research [Glowka, 1987; Finger and Glowka, 1989] to resolve problems with cutter design, manufacture, and utilization, thereby contributing very significantly to the advancement and commercialization of drag-bit technology [Falcone, 1995].