Metal polycrystalline diamond

Natural diamonds used for jewellery and for industrial purposes have been mined for centuries. The principal diamond mining centres are in Zaire, Russia, The Republic of South Africa, and Botswana. Synthetic diamonds are made by dissolving graphite in metals and crystallising diamonds at high pressure (12-15 GPa) and temperatures in the range 1500-2000 K [6] see section 3. More recently, polycrystalline diamond films have been made at low pressures by... 

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... 

Polycrystalline diamond or PCD is produced by sintering micron diamond powders under ultrahigh pressure (>5 GPa) in the presence of a metal catalyst such as cobalt. These materials are commercially available in a range of grain sizes and typically are... 

PCD (polycrystalline diamond) is obtained by sintering synthetic diamond powder in the presence of a metal binder (Co, Ni or Fe a low percentage by volume), at 1,350-1,500°C imder 5 GPa pressure. One may also sinter a layer of diamonds (0.5 mm thick) on a sintered hard metal substrate, the cobalt of the substrate thus participating in the sintering of the diamond and the adherence of the PCD on the substrate. Inserts up to 72 mm diameter and hardness of 5,000 to 8,000 HV may thus be attained. 

The development of low-pressure synthesis methods for diamond, such as the chemical vapor deposition (CVD) technique, has generated enormous and increasing interest and has extended the scope of diamond applications. Highly efficient methods have been developed for the economical growth of polycrystalline diamond films on non diamond substrates. Moreover, these methods allow the controlled incorporation of an impurity such as boron into diamond, which in this case forms a ptype semiconductor. By doping the diamond with a high concentration of boron (B/C = O.Ol), conductivity can be increased, and semi-metallic behavior can be obtained, resulting in a new type of electrode material with all of the unique properties of diamond, such as hardness, optical transparency, thermal conductivity and chemical inertness [1,2]. 

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). 

C fi3 diamond films can be deposited on a wide range of substrates (metals, semi-conductors, insulators single crystals and polycrystalline solids, glassy and amorphous solids). Substrates can be abraded to facilitate nucleation of the diamond film. 

Finally, the presence of ultrasound in the electrodeposition of metals can produce both massive metal and metal colloid [75]. The reduction of AuCLt- at polycrystalline boron-doped diamond electrodes follows two pathways forming... 

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