Cemented carbides are, from a technical point of view, one of the most successful composite materials. The physical and chemical aspects of the components (transition-metal carbides and iron-group metals) and of their interaction in hardmetals are reviewed with emphasis on the materials science point of view focusing on those compositions which have gained technical interest. Crystal structures and phase relationships are discussed in detail. The interaction of components (wetting, residual stresses) and some microstructural aspects (size, contiguity, and shape) are treated also. These fundamentals are the basis of understanding the production processes and the properties of cemented carbides.

Physical and chemical nature of cemented carbides

The invention is a composite polycrystalline diamond compact comprising at least one layer of diamond crystals and precemented carbide pieces which have been pressed under sufficient heat and pressure to create composite polycrystalline material wherein polycrystalline diamond and the precemented carbide pieces are interspersed in one another. Preferably, this composite material layer is disposed as a transition layer between the layer including the working surface of the compact and the substrate for the compact. In addition, the layer including the working surface may also be comprised of the composite material, with the general requirement that the volume percent of the polycrystalline diamond component in the layer including the working surface be higher than in the transition layer. Alternatively, the compact, rather than being divided into discrete layers, instead comprises a single layer of this composite material wherein the concentration of the polycrystalline diamond component is at its highest at the working surface of the compact and then decreases in the direction away from the working surface.

Composite polycrystalline diamond compact

Disclosed is a polycrystalline diamond or diamond-like element with greatly improved wear resistance without loss of impact strength. These elements are formed with a binder-catalyzing material in a high-temperature, high-pressure (HTHP) process. The PCD element has a body with a plurality of bonded diamond or diamond-like crystals forming a continuous diamond matrix that has a diamond volume density greater than 85%. Interstices among the diamond crystals form a continuous interstitial matrix containing a catalyzing material. The diamond matrix table is formed and integrally bonded with a metallic substrate containing the catalyzing material during the HTHP process. The diamond matrix body has a working surface, where a portion of the interstitial matrix in the body adjacent to the working surface is substantially free of the catalyzing material, and the remaining interstitial matrix contains the catalyzing material. Typically, less than about 70% of the body of the diamond matrix table is free of the catalyzing material.

High volume density polycrystalline diamond with working surfaces depleted of catalyzing material

The present invention provides a superhard polycrystalline diamond or diamond-like element with greatly improved resistance to thermal degradation without loss of impact strength. Collectively called PCD elements, these elements are formed with a binder-catalyzing material in a high-temperature, high-pressure process. The PCD element has a plurality of partially bonded diamond or diamond-like crystals forming at least one continuous diamond matrix, and the interstices among the diamond crystals forming at least one continuous interstitial matrix containing a catalyzing material. The element has a working surface and a body, where a portion of the interstitial matrix in the body adjacent to the working surface is substantially free of the catalyzing material, and the remaining interstitial matrix contains the catalyzing material. This translates to higher wear resistance in cutting applications, higher heat transfer capacity in heat sink applications, and has advantages in numerous other applications including hollow dies, indentors, tool mandrels, and wear elements.

Polycrystalline diamond partially depleted of catalyzing material

An abrasive compact with a substantially solid body is provided from a mass of abrasive particles which are bonded together on a particle-to-particle basis. A network of interstices is formed within the body by removing the metallic second phase by-product of a solvent catalyst sintering aid. The network of interstices is filled with the carbide by product of a non-catalyst sintering aid forking a solid body. A substrate is bonded to some of the particles and to some of the carbide filling the network of interstices.

Composite abrasive compact having high thermal stability

The present invention relates to a hard diamond sintered body for use in tools such as cutting tools, excavating tools and wire drawing dies and a method for producing the same. A sintered body obtained by sintering fine powders of diamond under a superhigh pressure has been already used in cutting tools, drill bits, wire drawing dies and the like of nonferrous metals and similars. However, they have said that such a diamond sintered body is inferior in heat-resistance. The present invention was achieved from the investigation aiming at the elimination of the above described defect of being inferior in heat-resistance of the conventional diamond sintered body. That is to say, according to the present invention, synthetic diamond powders containing a diamond synthesizing catalyst consisting of VIII group ferrous metals of the periodic table or Cr, Mn or Ta or alloys containing them used in the synthesis of diamond at a ratio of 0.01 to 10% by weight are exposed to a high temperature under the condition wherein diamond is unstable to graphitize a part or whole thereof and then the resulting raw materials are filled in a reaction vessel consisting of at least one kind of metals selected from a group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and the like and sintered at a superhigh pressure of 50 Kb or more and high temperature of 1,400° C. or more, under which diamond is stable, to obtain a diamond sintered body. In short, the present invention relates to a hard diamond sintered body, characterized by comprising intermetallic compounds consisting of metals or alloys thereof contained in said diamond as a raw material and metals composing a reaction vessel at a ratio of 0.01 to 12% by weight, and a method for producing the same. A hard diamond sintered body obtained according to the present invention is superior in heat-resistance and abrasion-resistance, in particular heat-resistance, of which lowness has been a disadvantage of the conventional diamond sintered body, can be remarkably and successfully improved without reducing the strength.

Diamond sintered body and the method for producing the same

The invention enables to obtain a compound sintered compact for use in a cutting tool having particularly high properties in respect of bonded strength, hardness, wear resistance, plastic deformability and rigidity by bonding a diamond or cubic boron nitride containing hard layer to a cemented carbide substrate with interposition of an intermediate bonding layer. A powder for forming the intermediate bonding layer comprising cubic boron nitride in an amount less than 70 volume %, the residual part principally consisting of a compound selected from among carbides, nitrides, carbonitrides or borides of 4a, 5a, 6a transition metals of the periodic table, an admixture thereof, or a mutual solid solution compound thereof, after pressing or in the state of powder, is placed on the cemented carbide substrate to a thickness less than 2 mm, or preliminarily applied to said cemented carbide substrate, further on said powder being placed a powder for forming the hard sintered compact containing diamond or cubic boron nitride in an amount in excess of 20 volume % after pressing or in the state of powder, the whole being hot pressed under an ultrahigh pressure and a high temperature to sinter the diamond or cubic boron nitride containing hard layer and the intermediate layer as well as to bond said hard layer, intermediate layer and substrate to each other, thereby enabling to obtain a compound sintered compact having the aforesaid superior properties for use in a cutting tool.

Compound sintered compact for use in a tool and the method for producing the same

The invention relates to a diamond sintered compact wherein diamond crystal particles are uniformly oriented in a particular direction and the method for producing the same, and has for an object to provide a diamond sintered compact having a high thermal conductivity particularly suitable for heat sink for use in the field of electronics. According to the invention, graphite is used as carbonaceous raw material, diamond crystal particles having such elongated shape that the ratio of the length of the long axis to that of the short axis is more than 2 being synthesized in such state that the greater part of the crystal particles have their long axes uniformly oriented in a particular direction, the crystal particles being sintered in the direction of the long axes thereof so that transformation of the graphite into diamond and sintering thereof may be accomplished synchronously. The invention has for an object to obtain a diamond sintered compact suitable for the aforesaid use by degassing reaction system raw material plugged into an air permeable container by heating it in vacuum in order to intercept gaseous components causing a decrease of thermal conductivity at the time of synthesizing diamond from carbonaceous material and a catalytic metal and sintering thereof, subsequently the air permeable part of the said container being sealed by means of soldering material preliminarily placed in contact with the said container.

Method for producing a diamond sintered compact

A sintered compact for use in a machining tool comprising 80 to 10 volume % of a high pressure form of boron nitride, and the balance a matrix of at least one binder compound material selected from the group consisting of a carbide, nitride, carbonitride, boride or silicide of IVa and Va transition metal of the periodic table, their mixtures as well as the solid solution of these compounds; the matrix forming a continuous bonding structure in the sintered body. A method of producing the compact comprises preparing a mix of 80 to 10 volume % of a high pressure form of a boron nitride powder with 20 to 90 volume % of at least one powdered binder compound selected from the group consisting of a carbide, a nitride, a carbonitride, a boride and a silicide of a IVa, or a Va metal, mixtures thereof or solid solutions of these compounds, and sintering the mix under pressures more than 20 Kb at temperatures higher than 700° C. for more than 3 minutes.

Sintered compact for a machining tool and a method of producing the compact

This invention relates to a cemented carbonitride alloy in which the hard phase consists of [(Group IVa metal).sub.A (Group Va metal).sub.B (Group VIa metal).sub.C ]-(CX NY)Z wherein A, B, C, X and Y are respectively mole fractions, Z is a mole ratio of the metalloid components to the metal components and there are among A, B, C, X, Y and Z the relations of A + B + C = 1, X + Y = 1, 4a + 5b + 6c + 4xz + 5yz ≧ 8.6, 0.05 ≦ y ≦ 0.50 and 0.85 ≦ Z ≦ 1.0. the hard phase is combined by at least one binder metal from the iron group and there are in the alloy structure WC phase and the hard phase having the crystal structure B1 and containing Ti in a proportion of at least 20 atomic percent to the metallic atoms.

Akio Hara

Papers

Diamond sintered body and the method for producing the same

Compound sintered compact for use in a tool and the method for producing the same

Method for producing a diamond sintered compact

Sintered compact for a machining tool and a method of producing the compact

Cemented carbonitride alloys