synthetic diamond

synthetic diamond

      man-made diamond that is usually produced by subjecting graphite to very high temperatures and pressures. Synthetic diamond resembles natural diamond in most fundamental properties, retaining the extreme hardness, broad transparency (when pure), high thermal conductivity, and high electrical resistivity for which diamond is highly prized. Because synthesis is an expensive process, large stones of gem quality are rarely made. Instead, most synthetic diamond is produced as grit or small crystals that are used to provide hard coatings for industrial equipment such as grinding wheels, machine tools, wire-drawing dies, quarrying saws, and mining drills. In addition, diamond films can be grown on various materials by subjecting carbon-containing gas to extreme heat; these layers can be used in cutting tools, windows for optical devices, or substrates for semiconductors.

      In 1880 the Scottish chemist James Ballantyne Hannay claimed that he had made diamonds by heating a mixture of paraffin, bone oil, and lithium to red heat in sealed wrought-iron tubes. In 1893 the French chemist Henri Moissan (Moissan, Henri) announced he had been successful in making diamonds by placing a crucible containing pure carbon and iron in an electric furnace and subjecting the very hot (about 4,000° C [7,000° F]) mixture to great pressure by sudden cooling in a water bath. Neither of these experiments has been repeated successfully.

      During the first half of the 20th century the American physicist Percy Williams Bridgman (Bridgman, Percy Williams) conducted extensive studies of materials subjected to high pressures. His work led to the synthesis by the General (General Electric Co.) Electric Company, Schenectady, N.Y., of diamonds in its laboratory in 1955. The stones were made by subjecting graphite to pressures approaching 7 gigapascals (1 million pounds per square inch) and to temperatures above 1,700° C (3,100° F) in the presence of a metal catalyst. Tons of diamonds of industrial quality have been made in variations of this process every year since 1960.

      In 1961 shock-wave methods, or explosive-shock techniques, were first used to produce diamond powder, and small quantities of the material are still formed this way. Beginning in the 1950s, Russian researchers began to investigate methods for synthesizing diamond by decomposition of carbon-containing gases such as methane at high heat and low pressure. In the 1980s commercially viable versions of this chemical vapour deposition method were developed in Japan.

* * *


Universalium. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Synthetic diamond — Synthetic diamonds of various colors grown by the high pressure high temperature technique Synthetic diamond is diamond produced in a technological process; as opposed to natural diamond, which is created in geological processes. Synthetic… …   Wikipedia

  • Diamond enhancement — Diamond enhancements are specific treatments, performed on natural diamonds (usually those already cut and polished into gems), which are designed to improve the gemological characteristics and therefore the value of the stone in one or more ways …   Wikipedia

  • Synthetic intelligence — (SI) is an alternative term for artificial intelligence. Harv|Poole|Mackworth|Goebbel|1998|p=1 It emphasizes the belief of many researchers that the intelligence of machines is not an imitation or in any way artificial; it is a genuine form of… …   Wikipedia

  • Diamond turning — Diamond flycutting Diamond turning is a process of mechanical machining of precision elements using lathes or derivative machine tools (e.g., turn mills, rotary transfers) equipped with natural or synthetic diamond tipped tool bits. The term… …   Wikipedia

  • Diamond — This article is about the mineral. For the gemstone, see Diamond (gemstone). For other uses, including the shape ◊, see Diamond (disambiguation) …   Wikipedia

  • Diamond simulant — Due to its low cost and close visual likeness to diamond, cubic zirconia has remained the most gemologically and economically important diamond simulant since 1976. The high price of gem grade diamonds, as well as significant ethical concerns of… …   Wikipedia

  • Diamond-like carbon — A ta C thin film on silicon (15 mm diameter) exhibiting regions of 40 nm and 80 nm thickness …   Wikipedia

  • Diamond (gemstone) — Part of a series on Diamonds Material Material properties Crystallographic defects Formatio …   Wikipedia

  • Diamond clarity — Part of a series on Diamonds Material Material properties Crystallographic defects Formatio …   Wikipedia

  • Diamond blade — A close up of a diamond blade, showing worn metal behind the diamonds on the blade. A diamond blade is a saw blade which has diamonds fixed on the blade s base to use the diamonds to cut hard or abrasive materials. There are many types of diamond …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”