Abstract: The invention is a process for preparing a sintered polycrystalline compact of cubic boron nitride, the compact produced by the process, and articles comprising the compact. A mixture is formed of cubic boron nitride grains and from 5 to 20 volume percent of binder material, or sintering aid, consisting essentially of silicon and an aluminum-containing material selected from the group consisting of aluminum, aluminum nitride, aluminum diboride, and mixtures thereof. The mixture is subjected to elevated pressure and temperature conditions sufficient to melt the binder material and at which the boron nitride is thermodynamically stable. The elevated pressure and temperature conditions are maintained for a time sufficient to sinter the compact. The compact is characterized by substantial intergranular CBN-CBN bonding, and has superior wear and impact resistance, thermal conductivity and stability.

Abstract: A polycrystalline diamond body with a plurality of faces having enhanced surface irregularities over at least a portion of at least one of the faces is disclosed. The polycrystalline diamond body with the enhanced surface irregularities attaches to other materials such as metal by conventional mounting techniques. The polycrystalline diamond bodies of this invention are without a carbide or metal backing. The pattern forming the enhanced surface irregularities of this invention can be predetermined or random. Similarly the pattern can be randomly distributed on the surface or positioned in a repeatable pattern. It is therefore not necessary that the surface irregularities be uniform in either shape or size. One method of forming the enhanced irregularities is during the press cycle during which the polycrystalline diamond is formed with screens, molds, or free standing bodies.

Abstract: A polycrystalline diamond and metal element for use as a cutting element for drilling holes or similar uses. The cutting element comprises a polycrystalline diamond center portion and at least one metal side portion. The metal side portion is made from a soft metal having a Young's Modulus less than approximately 45.times.10.sup.6 psi and is selected from a group comprising cobalt, nickel, iron, copper, silver, gold, platinum, palladium and alloys of these metals and intermetallic compounds containing these metals. Since the metal portion is sufficiently yielding the internal stresses formed in the polycrystalline diamond/metal bond during cooling and subsequent attachment to a tool body are signficantly reduced. The reduction the stress in the polycrystalline diamond/metal bond reduces fracturing in the diamond or metal and delamination of the polycrystalline diamond/metal interface during attachment to the tool and during use.

Abstract: An improvement in the design of engaging elements for drag type rotary drill bits is disclosed which consists of forming the abrasive-faced contact portion into curved shapes. An advantage of this engaging element is provided by the curved surface's tendency to direct the loosened material to the side of the contact portion. This self-cleaning action extends the life of engaging elements by reducing unnecessary regrinding of the already loosened material and by improving the engaging elements' ability to dissipate heat. Another advantage of this engaging element is that as it passes through the material the curved surface will exert stresses on the material differing in magnitude, direction and/or type at each point of the curve and thereby produce increased straining of the material. An increased straining of the material is especially desirable when drilling in shale or other plastic formations since it causes increased chipping of the material which aids in the removal of the material from the hole.

Abstract: An insert for a rotary type drag bit having two anchored components, an engaging element and a shank, is disclosed. The components are positioned into each other in interfitting relationship with the mating surfaces of the two components being at a non-perpendicular angle to a plane parallel to the front of the engaging element. This insert can then be placed into a receiving feature on the crown of a drill bit. The resulting engaging element to shank interface enables the forces encountered during drilling to be distributed over a larger surface area than conventional flat-on-flat two component attachments so that the bond is less likely to break. The effect of the drilling forces on the engaging element to shank interface is also reduced as the shearing forces are diminished and resolved into compressive forces and the shank provides a support for the interface bond against any remaining shearing forces.

Abstract: A cutting element for drilling holes is disclosed which consists of five cutting edges which are comprised of polycrystalline diamond or the like mounted to a central carbide substrate or similar hard material held by a rotatable shaft which can be inserted into a drilling machine. The polycrystalline material is unsupported with respect to torsional forces exerted upon it during drilling. An advantage of this cutting member is its ability to cut straight new holes in hard or abrasive materials for substantially longer periods of time than presently available rotary drills.

Abstract: A composite material is described which includes a mixture of individual diamond crystals and pieces of precemented carbide. The mixture is heated and pressurized to create intercrystalline bonds between the diamond crystals and chemical bonds between the diamond crystals and the precemented carbide pieces. The resulting composite polycrystalline diamond body exhibits excellent wear characteristics and impact resistance.