Iron, diamond synthesis

There are a number of binders used for pcD sintering. The most commonly used ones are iron group materials which are known to be good solvent/catalysts for diamond synthesis, namely cobalt, iron, nickel, and manganese or various combinations of these. 

Interest in the synthesis of diamond [7782-40-3] was first stimulated by Lavoisier s discovery that diamond was simply carbon it was also observed that diamond, when heated at 1500—2000°C, converted into graphite [7782-42-5]. In 1880, the British scientist Haimay reported (1) that he made diamond from hydrocarbons, bone oil, and lithium, but no one has been able to repeat this feat (2). About the same time, Moissan beheved (3) that he made diamond from hot molten mixtures of iron and carbon, but his experiments could not be repeated (4,5). 

Along a different line of research on shock compression of solids, namely, recovery experiments, great progress was also being made. Shock-induced recovery-type chemical reactions in encapsulated samples were first reported by Riabinin in 1956. Shock-induced metallographic transformation and the observation of twin bands in iron were first reported by Smith in 1958. Another major breakthrough was the shock-induced synthesis of diamond in 1961 by DeCarli and Jamieson. 

Simple substitution of other transition metals for iron subsequently showed that many of these elements were suitable solvents for the synthesis of diamond. 

Following the successful commercial synthesis of diamond in the 1950s, the second hardest material known, cubic boron nitride, cBN, was introduced to the market in the 1960s and is complementary to diamond. The iron, and its alloying elements, in ferrous materials has a tendency to react chemically with diamond under machining conditions and this can reduce the efficiency of the tool. cBN, however, although not as hard as diamond, does not react chemically with iron and is therefore particularly well suited to machining hard ferrous materials. 

Virtually all commercial HPHT synthesis of diamond uses iron, nickel, cobalt, manganese, chromium, and their alloys as catalyst-solvents. However, many other metals ean catalyze graphite-to-diamond formation at higher temperatures and pressures, as can water, silicates, and other minerals that are more akin to the environment in which natural diamonds grow in the earth. 

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