Superhard materials

ASM Committee on Tooling Materials, Superhard Tool Materials, Metals Handbook, Vol. 3, 9th ed., 1980, pp. 448—465. 

Superhard materials implies the materials with Vickers hardness larger than 40 GPa. There are two kinds of super-hard materials one is the intrinsic superhard materials, another is nanostructured superhard coatings. Diamond is considered to be the hardest intrinsic material with a hardness of 70-100 GPa. Synthetic c-BN is another intrinsic superhard material with a hardness of about 48 GPa. As introduced in Section 2, ta-C coatings with the sp fraction of larger than 90 % show a superhardness of 60-70 GPa. A typical nanostructured superhard coating is the heterostructures or superlattices as introduced in Section 4. For example, TiN/VN superlattice coating can achieve a super-hardnessof56 GPa as the lattice period is 5.2 nm[101]. 

Veprek, S., Reiprich, S., and Li, S., Superhard Nanocrystal-iine Composite Materials The TiN/Si3N4 System, Appl. Rhys. Lett., Vol. 66,1995, pp. 2640-2642. 

Veprek, S., Conventional and New Approaches Towards the Design of Novel Superhard Materials, Surf. Coat. Technol, Vol. 97,1997, pp. 15-22. 

D. M.Teter, Computational Alchemy The Search for New Superhard Materials, MRS Bulletin, 23,22 (1998). 

N. Dubrovinskaia, V. L. Solozhenko, N. Miyajima, V. Dmitriev, O. O. Kurakevych, and L.Dubrovinsky, Superhard Nanocomposite of Dense Polymorphs of Boron Nitride Noncarbon Material has Reached Diamond Hardness , Appl. Phys. Lett., 90,101912 (2007). 

C-M. Sung and M. Sung, Carbon Nitride and Other Speculative Superhard Materials , Mater. Chem Phys., 43,1 (1996). 

Figure 35. Low hardness (black) and high hardness (gray) values reported for the most important superhard materials. (Adapted from Ref. 7.)...

A cone 588 black superhard materials of hardness above 67 i/RC, e.g. carbides, thin sheet metal... 

One goal in the field of c-BN deposition is a coating which can be used for machining of iron-based materials. Such coatings offer the possibility to use a superhard material instead of the conventional carbide and oxide layers. 

Superhard BN parts are used as advanced grinding and cutting materials for processing metals. Typical trade names are Amborite, BZN HTZ, Elbor-RM, Kiborit, and Hexanit-R. 

Veprek S (2000) Nanostructured Superhard Materials. In Riedel R (ed) Handbook of Ceramic Hard Materials. Wiley VCH, Weinheim, p 104... 

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