Abstract: A cutting insert is provided with at least one crystal portion containing a first concentration of super-hard crystals, such as diamond or cubic boron nitride crystals, and core portion. The crystal portion and the core portion are united by amatrix of .beta.-silicon carbide and silicon and exclusively form a composite having an approximate thickness of at least 1/8 inch, thus obviating the need for bonding the cutting insert onto a carbide substrate. Additional crystal layers, having a concentration of crystals less than that of the first crystal layer, may be provided, the crystal and core layers being configured in a number of different configurations in order to optimize particular machining requirements.

Abstract: A cutting insert is provided with a core having upper and lower surfaces and a recess in the upper surface. Crystal portions containing a dispersion of super-hard crystals are disposed at predetermined locations on the periphery of the upper surface of the core outside of the recess, and a layer of metal is bonded to the upper surface of the core inside the recess. The layer of metal extends upwardly beyond the upper surface. The layer of metal is provided to produce highly parallel upper and lower surfaces of the cutting insert in order to facilitate the mounting of the insert into a cutting body. The layer of metal further functions to absorb shock during a cutting operation.

Abstract: A technique for providing an intermediate composite adapted to be reaction sintered to produce a cutting insert includes the steps of positioning a pellet of material disposed within a holder on top of a first plunger within a mold by moving the holder and pellet into alignment with the plunger through the use of a first feeder device. A powder mix is then disposed adjacent to at least a portion of the pellet within the mold by a second feeder device. The powder mix and the pellet are compressed together in the mold to produce the intermediate composite which is then removed from the mold for reaction sintering in accordance with the press and treat technique.

Abstract: An indexable composite cutting insert which is generally polygonal in plan view and includes spaced upper and lower surfaces, is composed of a core, such as a SiC-Si composite material, with the corners along one surface of the composite cutting insert being made of a superhard material of diamond or cubic boron nitride crystals bonded to the core. The limited use of super-hard crystals in the critical areas of the cutting edges of the insert results in significant cost savings, both in manufacturing costs and costs of materials, as well as minimum warpage of the insert. In addition, improved wear resistance of the cutting edges of the insert is obtained.

Abstract: A silicon carbide cutting insert is prepared using a pre-pressed core dispersion of carbon fiber, carbon black, and filler in a temporary binder such as paraffin. The pre-pressed core dispersion is enveloped with a dispersion of super-hard crystals and carbon black in the temporary binder and compacted with the pre-pressed core to form an intermediate composite which is subsequently heated to allow for the removal of the temporary binder and the infiltration of liquefied silicon. The composite is then sintered to form a matrix of silicon and silicon carbide throughout the cutting insert.

Abstract: A wear-resistant annular insert which may be used as a wire drawing die, includes an annular exterior layer and an annular interior layer, containing diamond or cubic boron nitride crystals, bonded to the interior of the annular exterior layer by a .beta.-silicon carbide and silicon matrix. The insert is formed by preparing a first dispersion of carbon fiber, carbon black and filler in a temporary binder such as paraffin, and preparing a second mixture of the crystal material and carbon black in the temporary binder. The first and second mixtures are compressed in a mold such that the first and second mixtures form the exterior and interior layers, respectively. The layers are then heated to allow for the removal of the temporary binder and the infiltration of liquefied silicon. The layers are then sintered to produce the annular insert.

Abstract: A cutting insert having a cutting portion comprising a dispersion of diamond crystals in a matrix of .beta.-silicon carbide and silicon nitride is produced by forming a first dispersion of diamond crystals evenly coated with carbon black in a temporary binder, and forming a second dispersion of carbon fiber, carbon black and filler in a temporary binder. The first and second dispersions are compacted together to produce an intermediate composite which is heated in a vacuum furnace in order to remove the temporary binder and allow liquefied silicon to infiltrate the composite. The composite is then sintered and subjected to nitrogen, wherein elemental silicon at the surface of the composite reacts with the nitrogen to produce silicon nitride.

Abstract: A composite wafer bonded to a carbide substrate is formed by preparing a dispersion of super-hard crystals and carbon black in a temporary binder such as paraffin, by preparing a base mixture of carbon fiber, carbon black and filler in the temporary binder, and by preparing an additional mixture of cobalt and carbon black in the temporary binder. The dispersion, base mixture and additional mixture are compacted to form an intermediate composite, the additional mixture forming a layer on one surface of the base mixture. The intermediate composite is heated to allow for the removal of the temporary binder and the infiltration of liquefied silicon into the composite which is then reaction sintered to form the composite wafer.

Abstract: Sintered silicon carbide composites containing diamond crystals are made through a process wherein a first dispersion of diamond crystals and carbon black in paraffin is formed, along with a second dispersion of carbon fiber, carbon black and filler in paraffin. One of the dispersions is compacted to produce a physically stable intermediate compact which is then recompacted with the remaining dispersion to produce a binary compact. The latter is subjected to a vacuum for a period of time at a temperature sufficient to vaporize essentially all of the paraffin, after which the binary compact is infiltrated with liquid silicon and sintered to produce a .beta.-silicon carbide binder uniting the resulting composite.

Abstract: A blank adapted to be mounted on a substrate to form a cutting insert is formed by preparing a crystal dispersion of super-hard crystals, such as diamond or cubic boron nitride crystals, and carbon black in a temporary binder, and a core dispersion of carbon fiber, carbon black and filler in a temporary binder. The crystal dispersion and the core dispersion are placed in a mold to respectively form a core dispersion layer and a crystal dispersion layer which forms a ring about the periphery of the core dispersion layer on the upper surface thereof. The crystal and core dispersion layers are compacted with a chamfered plunger applied to the lower surface of the core layer to form an intermediate composite having a recess at the lower surface thereby compressing the dispersions to a substantially uniform compaction throughout the intermediate composite. The intermediate composite is then heated to allow for the removal of the temporary binder and the infiltration of liquified silicon.

Abstract: Sintered silicon carbide composites containing diamond crystals are made through a process wherein a first dispersion of diamond crystals and carbon black in paraffin is formed, along with a second dispersion of carbon fiber, carbon black and filler in paraffin. One of the dispersions is compacted to produce a physically stable intermediate compact which is then recompacted with the remaining dispersion to produce a binary compact. The latter is subjected to a vacuum for a period of time at a temperature sufficient to vaporize essentially all of the paraffin, after which the binary compact is infiltrated with liquid silicon and sintered to produce a .beta.-silicon carbide binder uniting the resulting composite.

Abstract: A process for producing a sintered silicon carbide composite includes the steps of forming a first dispersion of diamond crystals and carbon black in paraffin, as well as forming a second dispersion of carbon fiber, carbon black and filler in paraffin. The two dispersions are compacted together to form an integral bi-layer composite which is then subjected to a vacuum for a period of time at a temperature sufficient to vaporize essentially all of the paraffin. Silicon is heated to cause liquification and direct infiltration into both layers of the composite after which the composite is sintered under conditions sufficient to produce a .beta.-silicon carbide binder uniting the composite.

Abstract: A method of making shaped articles from powders comprises forming a cup mold of a destructible organic polymeric material such as nylon, cellulose acetate, poly(methyl methacrylate), polypropylene or polyethylene. The inner surface of the mold corresponds in configuration with the outer surface configuration desired in the shaped article. This mold is placed in a support member and filled with a measured quantity of powder. A plunger composed of a metal having a high specific gravity is placed on top of the powder, and the mold, mold support, powder and plunger combination is positioned in the swing bucket of a centrifugal apparatus where it is subjected to centrifugal force sufficient to achieve the desired degree of compaction of the powder. The mold is then removed and subjected to treatment at a temperature which is sufficient in the first instance to destroy the polymeric mold material, and then sufficient to sinter the powder.

Abstract: A method of making shaped articles from powders comprises forming a cup mold of an organic polymeric material such as nylon, cellulose acetate, polymethylmethacrylate, polypropylene or polyethylene. The inner surface of the mold corresponds in configuration with the outer surface configuration desired in the shaped article. This mold is placed in a support member and filled with a measured quantity of powder. A plunger composed of a metal having a high specific gravity is placed on top of the powder, and the mold, mold support, powder and plunger combination is positioned in the swing bucket of a centrifugal apparatus where it is subjected to centrifugal force sufficient to achieve the desired degree of compaction of the powder. The mold is then removed and subjected to treatment at a temperature which is sufficient in the first instance to eliminate the polymeric mold material, as by melting or burning, and then sufficient to sinter the powder.