Polycrystalline diamond tools

Sintered polycrystalline diamond tools are much more expensive than conventional cemented-carbide or ceramic tools because of the high cost of the processing technique and the finishing methods used. Diamond tools, however, are economical on an overall-cost-per-part basis for certain applications because of long life and increased productivity. 

The reinforcement material is embedded into the matrix. The reinforcement does not always serve a purely structural task (reinforcing the compound), but is also used to change physical properties such as wear resistance, friction coefficient, or thermal conductivity. The reinforcement can be either continuous, or discontinuous. Discontinuous metal matrix composites can be isotropic, and can be worked with standard metalworking techniques, such as extrusion, foiging or rolling. In addition, they may be machined using conventional techniques, but commonly would need the use of polycrystalline diamond tooling (PCD). 

A wide range of cutting-tool materials is available. Properties, performance capabilities, and cost vary widely (2,7). Various steels (see Steel) cast cobalt alloys (see Cobalt and cobalt alloys) cemented, cast, and coated carbides (qv) ceramics (qv), sintered polycrystalline cubic boron nitride (cBN) (see Boron compounds) and sintered polycrystalline diamond tbin diamond coatings on cemented carbides and ceramics and single-crystal natural diamond (see Carbon) are all used as tool materials. Most tool materials used in the 1990s were developed during the twentieth century. The tool materials of the 1990s... 

Cemented tungsten carbides also find use as a support for polycrystalline diamond (PCD) cutting tips, or as a matrix alloy with cobalt, nickel, copper, and iron, ia which diamond particles are embedded. These tools are employed ia a variety of iadustries including mineral exploration and development oil and gas exploration and production and concrete, asphalt, and dimension stone cutting. 

PDC bits get their name from the polycrystalline diamond compacts used for their cutting structure. The technology that led to the production of STRATAPAX drill blanks grew from the General Electric Co. work with polycrystalline manufactured diamond materials for abrasives and metal working tools. General Electric Co. researched and developed the STRATAPAX (trade... 

Limited supply, increasing demand, and high cost have led to an intense search for an alternative, dependable source of diamond. This search led to the high pressure (ca 5 GPa (0.5 x 106 psi)), high temperature (ca 1500°C) (HP—HT) synthesis of diamond from graphite in the mid-1950s (153—155) in the presence of a catalyst—solvent material, eg, Ni or Fe, and the subsequent development of polycrystalline sintered diamond tools in the late 1960s (156). 

Superabrasive Tools. The second class of tool materials used for FSW of HTM is superabrasives. Superabrasives are materials that are formed in presses under extreme temperature and pressure. The two superabrasives that have been used in FSW are polycrystalline diamond (PCD) and PCBN. Both materials consist of small crystals of ultrahard material (diamond or CBN) bonded together in a skeletal matrix with a second-phase material that serves as a catalyst for the formation of the matrix. Reference 5 gives a summary of the characteristics of superabrasive materials. 

Polycrystalline diamond has been used for aluminum-matrix composites reinforced with particulate silicon carbide, boron carbide, or alumina. It also shows promise as a tool material for welding titanium, although this work is only in a preliminary stage. 

Common tool materials for machining aluminum and magnesium alloys are cemented carbide and polycrystalline diamond (PCD). Because of the strong affinity between aluminum and titanium, only tungsten-based cemented carbide tools are used for alloys with relevant aluminum contents. 

A special type of abrasive is CVD (Chemical Vapor Deposition) polycrystalline diamond film with sharp edges of micrometer size diamond crystallites which are used for micro-pencil grinding tools (Gabler et al. 2003). 

Axinte D, Srinivasu DS, Kong MC, Butler-Smith PW (2009) Abrasive waterjet cutting of polycrystalline diamond a preliminary investigation. Int J Mach Tools Manuf 49(10) 797-803... 

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