Superhard nanostructured

Some theoretical aspects were discussed to show the generality of the principle for the design of superhard nanocomposites. The present review was complemented by a brief summary of the recent development in the field of heterostructures which represent another approach to the design of superhard nanostructured materials. 

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

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. 

Of course, one should keep in mind that the high structural stability of the nanostructure at high temperature is not necessary condition for the occurrence of the superhardness. Any phenomenon which avoids the grain boundary sliding will... 

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. 

Nanocomposite coatings, which require thermo-dynamically driven phase segregation. The superhardness of nanocomposites lies in the nanostructured condition of the coatings, whose structural stability could result from a spinodal... 

R.A. Andrievski, Nanostructured superhard films as typical nanomaterials. Surf. Coat. Technol. 201(13), 6112-6116 (2007)... 

In Chapter 16, the high-pressnre synthesis of carbon nanostructured superhard materials is presented by V. D. Blank, S. G. Buga, G. A. Dubitsky, K. V. Gogolinsky,... 

High-Pressure Synthesis of Carbon Nanostructured Superhard Materials... 

S5mthesis of Carbon Nanostructured Superhard Materials 413 Table 16.2 Cgo sjmthesized at P = 8 GPa."... 

---