Researchers at the Carnegie Institution

Researchers at the Carnegie Institution in Washington discovered in 2004 a process to synthesize within 24 hours diamonds that are more than 50% harder than natural diamonds.

Approximately 90% of all diamond cutting powder today is synthetic. The majority of synthetic diamonds are still produced under high pressure. A growing proportion is manufactured by evaporation at low pressure. The small crystals produced by this technique are used as an ultra-hard coating in the manufacture of preformed tools.

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Zirconia consists of zirconium (IV) oxide (ZrO2) and is a popular substitute for synthetic diamonds.

Direct conversion of organic carbon into the high pressure conditions inside the Earth. This is the standard process by which diamonds are formed in nature. The problem with this hypothesis is that if carbonado is created by a phase transition in organic graphite, it should be found all over the world. However, carbonado can only be found in the Central African Republic and Brazil, areas where no other types of diamonds are found.
Shock metamorphosis during meteorite impacts on the earth’s surface. What is not true is that shock metamorphosis usually results in the formation of hexagonal diamonds (lonsdaleite), not carbonado.

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Radiogenic formation of diamonds by natural radioactive decay of uranium and thorium. The problem with this hypothesis is that the energy of these decay reactions is too small to form carbonado in the size in which it is found (up to 500 μm).

Carbonado contains traces of nitrogen and hydrogen, analysis of the hydrogen isotopes has shown that they originate from supernovas. This could mean that carbonado may have an extraterrestrial origin. The idea is that carbonado is related to carbon-rich interstellar dust and is formed in the vicinity of carbon stars. Then it was incorporated into a meteorite that later struck Earth.

Tungsten carbide or Widia is a ceramic material, which arises from tungsten and carbon and is a mixing crystal. This relatively cheap material is known for its high hardness, and is therefore used in cutting equipment. The carbon atoms go into the openings of the tungsten lattice. It is made by reducing tungstic oxide and carbon with the help of hydrogen.

It was first made in 1914. In 1926, the German company Krupp (now known as Kennametal) hardened tungsten carbide and in 1962 Krupp succeeded in coating cutting plates with the hardened tungsten carbide.

Tungsten carbide can be made very hard by sintering it. During sintering, grains of material are heated to a temperature at which they do not melt. In this way, the contact points between the grains grow, which can result in a very hard material. Usually, 6 to 10% cobalt is also added as a binding agent.

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Sintered tungsten carbide is known under the brand name Widia, which is derived from the German for Who Diamond (translation: “like diamond”).

Applications
It is a very hard material that can be used to replace the more expensive diamond in, for example, (dental) drills and in cutting heads of a tunnel drill. It is also used for the blades of cutting machines. It even occurs as part of a ballpoint pen (the “ball” from “ballpoint pen”). Widia drills are drills of which the tip is covered with hardened tungsten carbide. In this case, a plate of tungsten carbide is brazed into the carrier material (usually steel) by brazing, a method that is also used for certain types of stone cutters. These drills and chisels can be used in concrete, hard stones and tile walls.

Due to the high density and hardness, tungsten carbide is also used in armour-piercing ammunition, see rod penetrator. Tungsten carbide is most commonly used in the machining metal industry as a cutting material.

Glass consists of a mixture of silicon dioxide, the main component of quartz sand and metal oxides. By heating it, it melts into a thick substance that is easy to form and hardens by cooling.

From a scientific point of view, crystal glass is not a crystal. As with ordinary glass, the molecules are not arranged in an orderly manner in a crystal structure, but form an amorphous solid.

According to an EU directive from 1969, crystalline glass is the general description for glassware containing metallic oxide, but there are several categories within that description. Only the more luxurious variants must contain lead: