The development of superhard abrasives

2.1 Preliminary phase of synthetic diamond

In 1796, Tennant, a British scientist, revealed for the first time that diamond is composed of pure carbon through the famous experiment of burning diamond to produce carbon dioxide, and from then on, mankind began to explore the journey of synthetic diamond. After all kinds of attempts and efforts, it was not until the middle of the 20th century that Simon and Berman obtained the Graphite-Diamond equilibrium phase diagram through experiments and speculation, which made synthetic synthesis possible

2.2 Development stage of synthetic diamond by HPHT technology

In 1953, Liander and others in Sweden successfully synthesized diamond through high temperature and high pressure (HPHT) technology. Subsequent studies have shown that if catalysts such as boron oxide, lithium nitride, calcium nitride or magnesium nitride are added, the synthetic pressure and temperature can be reduced to 4~7GPa and 1200~1700℃, and the prepared diamond and cBN microcrystals are mainly used for abrasive. Relatively speaking, the preparation of large particle single crystal cBN is more difficult, and the maximum is 1-3mm at present.

2.3 CVD technology synthetic diamond development stage

For cBN film materials prepared by CVD method, although there were reports of cBN film preparation in 1979, it was not until 1987 that the cBN film was truly prepared, and it was found that there were other transitional layers of BN structure between the matrix and cBN film, which would affect its adhesion. With the development of science and technology, the thickness of cBN film has reached 2 ~ 3μm, and the adhesion with the matrix has been enhanced.

2.4 Development stage of nanometer diamond powder preparation

It was not until the 1990s that nanoscale diamond microcrystals synthesized by the explosion method entered the market, and this method can obtain 5nm microcrystals due to the extremely fast cooling rate.

2.5 Single-crystal diamond tool development stage

About in the 1960s, material researchers began to apply natural diamond, artificial diamond and cubic boron nitride directly to mechanical processing such as cutting and grinding of materials through simple bonding or welding.

2.6 Development stage of polycrystalline diamond and polycrystalline cubic boron nitride materials

Generally considered to be epoch-making significance is the PCD composite sheet produced by GE (cemented carbide as the carrier, the formation of 0.3-0.7mm thick PCD layer on it), since then many countries and companies have launched the research and preparation of PCD and PcBN.

2.7 Development stage of new superhard materials

About the 1990s, the world's major superhard materials industry companies and research institutions also began to develop new superhard materials. With the deepening of research and development, people have found that the single substance or compound composed of carbon, boron, nitrogen, oxygen and other light element atoms, and the compounds formed by these light elements and transition cluster elements (W, Re, Ir, Pt, Os, etc.) have extremely high hardness. Its high hardness mainly comes from the above simple substances and compounds can form a high atomic stacking density, super covalent bond three-dimensional network structure, high bond binding energy, has a very high external force resistance

Superhard materials have been prepared and are being studied

(a) diamond or diamond-like superhard compounds formed between B, N, C and O elements;

(b) superhard compounds formed between transition cluster metals and B, N, C, O elements.