Superhard coatings

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. and Reiprich, S., A Concept for the Design of Novei Superhard Coatings," Thin Solid Films, Vol. 268,... 

Veprek, S., Haussmaim, M., Reiprich, S., Li, S., and Dian, J., "Novel Thermodynamically Stable and Oxidation Resistant Superhard Coating Materials, Surf Coat. Technol., Vol. 86/... 

Veprek, S., Veprek-Heijman, M., Karvankova, P., Fhochazka, J. 2005. Different approaches to superhard coatings and nanocomposites. Thin Solid Films 476 1-29. 

We are primarily interested in superhard coatings for cutting tools, which have to be deposited on appropriate substrates, such as cobalt cemented carbide or steel. Thus, the preparation technique should assure a high nitrogen activity and a sufficient activation energy for the thermodynamically driven segregation of the... 

Raveh A, Zukerman I, Shneck R, Avni R, Fried I. Thermal stability of nanostructured superhard coatings a review. Surf Coat Technol 2006 201(13) 6136-42. 

Superhard coatings are of special interest in this regard. They can roughly be classified in four groups ... 

S. Veprek, S. Reiprich, A concept for the design of novel superhard coatings. Thin Solid Films 268(1-2), 64-71 (1995)... 

Veprek S, Haussmann M, Reiprich S, Shizhi L, Dian J, Novel thermodynamically stable and oxidation resistant superhard coating materials . Surf Coat Technol, 1996,... 

Veprek et al. [120,121,144] present the explanation of the superhardness for the nanocomposite coating on the basis of the absence of dislocation activity in a few-nanometre-... 

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

Veprek, S., Nesladek, P., Niederhofer, A., Glatz, F., Jilek, M., and Sima, M., "Recent Progress in the Superhard Nanocrystalline Composites Towards Their Industrialization and Understanding of the Origin of the Superhardness, Surf. Coat. Technol,Vo. 108/109,1998,pp. 138-147. 

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. 

Condensation combined with ion bombardment allows to fabricate nanostructured quasibinary (TiN/ZrN) and triple (Ti-Zr-N) nitride coatings. These coatings can be ranked as a superhard material due to their mechanical properties. 

S. Miyake and R. Kaneko. Micro-Tribological Properties and Applications of SuperHard and Lubricating Coatings. In Y. Tzeng, M. Yoshikawa, M. Murakawa, and A. Feldman, editors. Applications of Diamond Films and Related Materials. Materials Science Monographs, Volume 73. Elsevier, New York, 1991, p. 691. 

Kuzmiak V et al (chairs/eds) (2007) Metamaterials II 16-18 Apr 2007, Prague, Czech Republic spons. by SPIE Europe cooperating org. SPIE Czech Republic Chapter et al. publ. by SPIE -The International Society for Optical Engineering, SPIE Lee J et al (eds) (2005) Innovative superhard materials and sustainable coatings for advanced manufacturing. Kluwer, Boston, MA... 

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