General Electric Company

Norton Company

Hyun S Cho

Sy-Hwa Chen

Chien-Min Sung

Leo Merrill

Paul D Gigl

Frank J Csillag

Superabrasive cutting elements, backed compacts and methods for their manufacture are disclosed wherein metal coated superabrasive particles are cemented under HPHT conditions. The superabrasives bond to the metal of the coating and the metal coatings of adjacent particles bond to each other forming a matrix. A binding aid with thermal expansion characteristics close to that of the superabrasive particle can be infiltrated through or otherwise mixed with the particles to assist in the bonding between the metal coatings and to fill in voids. Catalyst and non-catalyst binding aids can also be used. Uncoated, smaller superabrasive particles can be interstitially dispersed among the coated particles to increase the superabrasive concentration and can self bond to form a cemented/sintered structure. Tungsten is a preferred metal coating and silicon is a preferred binding/sintering aid. The superabrasive can be diamond, cubic boron nitride, boron doped diamond or crushed, sintered polycrystalline aggregates. The free-standing cutting element can have a brazeable layer and the compact can be backed with, for example, cemented tungsten carbide. Free-standing cutting elements can be thermally stable up to 1,200.degree. C. Backed compacts can be thermally stable up to 1,100.degree. C.

Cemented and cemented/sintered superabrasive polycrystalline bodies and

Superabrasive cutting elements, backed compacts and methods for their manufacture are disclosed wherein metal coated superabrasive particles are cemented under HPHT conditions. The superabrasives bond to the metal of the coating and the metal coatings of adjacent particles bond to each other forming a matrix. A binding aid with thermal expansion characteristics close to that of the superabrasive particle can be infiltrated through or otherwise mixed with the particles to assist in the bonding between the metal coatings and to fill in voids. Catalyst and non-catalyst binding aids can also be used. Uncoated, smaller superabrasive particles can be interstitially dispersed among the coated particles to increase the superabrasive concentration and can self bond to form a cemented/sintered structure. Tungsten is a preferred metal coating and silicon is a preferred binding/sintering aid. The superabrasive can be diamond, cubic boron nitride, boron doped diamond or crushed sintered polycrystalline aggregates. The free-standing cutting element can have a brazeable layer and the compact can be backed with, for example, cemented tungsten carbide. Free-standing cutting elements can be thermally stable up to 1,200.degree. C. Backed compacts can be thermally stable up to 1,100.degree. C.

Disclosed is a method for manufacturing a polycrystalline sandwich compact comprising a polycrystalline diamond or CBN core interposed between outer support layers. The method comprises providing an assembly comprising a mass of diamond or CBN particles, a pair of compression disks, and two metal layers, one of each of which is interposed between said mass and each said compression disk. When said mass comprises diamond particles, a source of sintering aid/catalyst for diamond sintering also is provided in the assembly and optionally for CBN particles a source of sintering aid/catalyst for CBN sintering is provided in said assembly. The assembly then is subjected to HP/HT sintering for forming a sintered polycrystalline diamond or CBN core having two metal-derived support layers adherently bound thereto.

Method for making polycrystalline sandwich compacts

Disclosed is a process for fabricating a supported polycrystalline diamond or CBN bi-layer compact which comprises forming a sintered polycrystalline or CBN compact which preferably is a thermally-stable compact. A cemented carbide support is separately formed. The compact and the support then are mated with a layer of diamond or CBN crystals having the largest dimension of between about 30 and 500 micrometers interposed therebetween. A source of catalyst/sintering aid material is provided in association with the layer of interposed crystals. The entire assembly then is subjected to HP/HT conditions and for a time adequate for converting the diamond or CBN crystals into a polycrystalline diamond or CBN layer and for producing the bi-layer supported compact of the present invention.

Fabrication of supported polycrystalline abrasive compacts

A process improvement is disclosed for making diamond wire die compacts of the type which are generally described as an inner polycrystalline diamond mass surrounded by and bonded to a mass of metal bonded carbide, such as cobalt cemented tungsten carbide. It is known to make these dies by high pressure-high temperature processes, typical conditions being 50 kbar and temperatures in excess of 1300.degree. C. The improvement comprises disposing within the reaction sub-assembly (e.g. metal carbide and diamond within a zirconium cup) a set of discs of specific materials in specified arrangements. For example, on one side of the mass of metal carbide and diamond is disposed one disc of a diamond catalyst/solvent and one disc of a refractory metal such as molybdenum, and on the other side are disposed at least two discs of one or more transition metals such as zirconium. These discs are generally placed inside the sub-assembly cup. By means of this process modification, process yields have been significantly improved through decreasing the occurrence of defects in the dies and by decreasing the reaction time.

Axial sweep-through process for preparing diamond wire die compacts

The high pressure/high temperature catalyst sweep through process for making diamond and cubic boron nitride compacts has been improved by adding an intermediate metal or metal alloy. The added metal (whether alone or contained in an alloy) has a melting point below that of the catalyst (e.g. cobalt), is miscible with the catalyst, and preferably sweeps through the mass of abrasive crystals first. This modification has reduced flaw formation in such compacts.

Growing community of inventors

Sandy, UT, United States of America

Hyun S Cho