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Superhard materials, hardness

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]. [Pg.157]

Figure 35. Low hardness (black) and high hardness (gray) values reported for the most important superhard materials. (Adapted from Ref. 7.)... 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... [Pg.207]

Veprek S (2000) Nanostructured Superhard Materials. In Riedel R (ed) Handbook of Ceramic Hard Materials. Wiley VCH, Weinheim, p 104... [Pg.164]

The utilization of the outstanding mechanical and wear properties of cubic BN and related superhard materials has been demonstrated, although further process improvements are necessary before a more general use can be expected. Superhard cubic BN exhibits superb inertness to hot steel surfaces under conditions in which diamond would be severely attacked. Other tetrahedral structures, for instance, BCN and B2O, are anticipated to display similar attractive properties. The high-pressure phase B2O is a semiconductor with a band gap of 0.25 eV and a hardness between that of boron carbide and diamond. [Pg.410]

Figure 10.24 Schematic relationship between Vickers hardness and shear modulus. Adapted from D.M. Teter, 1998, Computational Alchemy The Search for New Superhard Materials , Materials Research Society Bulletin 23 (January) 22... Figure 10.24 Schematic relationship between Vickers hardness and shear modulus. Adapted from D.M. Teter, 1998, Computational Alchemy The Search for New Superhard Materials , Materials Research Society Bulletin 23 (January) 22...
However, the experimental evidence for the synthesis and structure of dense superhard C3N4 phases reported in the literature is not unambiguous. Thus, future research should be focused on the synthesis of sufficient amounts of these new superhard materials and on their structural characterization. The structures of all C3N4-polymorphs reported so far still remain to be verified by single crystal X-ray or electron diffraction. Furthermore, the difficulties in the determination of reliable hardness values of these new materials not only at room temperature but also at elevated temperatures have to be overcome. Diamond will not lose its reputation as the hardest material until the newly developed phases and compounds have been characterized in detail and can be produced in reasonable amounts. [Pg.1097]

Superhard materials for defined edge tooling may be defined as materials with a hardness exceeding 3,000 HV. [Pg.1183]

Among the transition metal nitrides, cubic CrN has been identified as a better coating and superhard material due to its hardness, excellent corrosion, oxidation... [Pg.77]

R.G. Veprek, D.M. Parks, A.S. Argon, S. Veprek, Non-linear finite element constitutive modeling of mechanical properties of hard and superhard materials studied by indentation. Mater. Sci. Eng. Struct. Mater. Prop. Microstruct. Process. 422(1-2), 205-217 (2006)... [Pg.657]

The diamond-containing composite material developed at the Institute for Superhard Materials is used to fit drilling bits. This material has a dual-phase structure with cracked hard particles in which the energy dissipation in the process of microcracking occurs prior to its deformation. Therefore, we have a composite of dissipative structure wherein microcracks influence its fracture mechanism deterioratively. [Pg.264]

Superhard materials Materials having a hardness greater than about 40 GPa. Examples Diamond = 100 GPa cubic BN = 40 GPa. [Pg.709]

These achievements are mainly linked to the discovery, study and development of hard and superhard materials such as ceramics and cermets. [Pg.325]

Figure 9.1. Principal methods ofpreparation ofpowders for hard and superhard materials... Figure 9.1. Principal methods ofpreparation ofpowders for hard and superhard materials...
Figure 9.1 illustrates the principal methods of preparation of powders for hard and superhard materials. These materials are formed by techniques of powder ceramic-metallurgy, as per the following alternatives ... [Pg.328]

As we have seen in this chapter, on various occasions, the excellent combination of properties on account of their composite nature explains the almost unequalled success of sintered hard metals in a large number of fields of technology. They are still growing in importance despite having been around for 75 years. The appearance of new materials (ceramics, superhard materials) has not dampened the momentum of fundamental and applied research on sintered hard metals. The accent is now placed on technoeconomic gains and the increase in duration of the life of tools, combined with effective methods of recychng. [Pg.349]

Hardness is the most important characteristic of superhard materials. It indicates the potential of the cutting tool this is the field of application where superhard materials are used the most. Cutting (or scratching) is the basis of the first primitive Mohs hardness scale. Hardness is defined as the load on an indenter divided by the projected area. Several hardness measurement methods are used in practice, the major ones being indentation and sclerometry (scratch at a constant indenter load). A detailed comparison of the indentation and sclerometry methods is given in [15]. These methods conform well with each other. Sclerometry implies a greater plastic deformation as compared with indentation [15],... [Pg.407]

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). [Pg.200]


See other pages where Superhard materials, hardness is mentioned: [Pg.379]    [Pg.2]    [Pg.367]    [Pg.174]    [Pg.220]    [Pg.29]    [Pg.38]    [Pg.429]    [Pg.109]    [Pg.111]    [Pg.111]    [Pg.129]    [Pg.255]    [Pg.1035]    [Pg.1035]    [Pg.1072]    [Pg.1183]    [Pg.181]    [Pg.28]    [Pg.60]    [Pg.357]    [Pg.26]    [Pg.209]    [Pg.625]    [Pg.654]    [Pg.426]    [Pg.6]    [Pg.162]    [Pg.217]    [Pg.11]   
See also in sourсe #XX -- [ Pg.407 ]




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