Cubic Boron Nitride cBN

A wide range of cutting-tool materials is available. Properties, performance capabilities, and cost vary widely (2,7). Various steels (see Steel) cast cobalt alloys (see Cobalt and cobalt alloys) cemented, cast, and coated carbides (qv) ceramics (qv), sintered polycrystalline cubic boron nitride (cBN) (see Boron compounds) and sintered polycrystalline diamond tbin diamond coatings on cemented carbides and ceramics and single-crystal natural diamond (see Carbon) are all used as tool materials. Most tool materials used in the 1990s were developed during the twentieth century. The tool materials of the 1990s... 

Superabrasive wheels include diamond wheels and cubic boron nitride (CBN wheels. 

In this chapter, heteroepitaxial growth of diamond particles and films on cubic boron nitride (cBN), Ni, Co, Cu, TiC, BeO, NijSi, graphite, sapphire, and Si will be described. The crystal parameters of these and other materials are listed in Appendix E. 

Cubic boron nitride (cBN) has a zinc blende-type crystal structure with a lattice constant of 3.615 A, which is very close to that of diamond (3.567 A). The difference is only about 1.3%. According to RHEED measurements with the electron beam parallel to the 111 layer of cBN, a growth of diamond by DC plasma CVD on cBN(lll) [150] using c = 0.5%CH4/H2, T = 900°C, and F=180Torr led to a result that a smooth (111) layer of diamond was epitaxially deposited in such a way that the [110] direction of diamond was parallel to that of cBN. Namely, D 111 //cBN(lll and D[110]//cBN[110]. In the RHEED pattern, however, extra spots were observed, which were presumably due to the twinnings of (111 diamond layers. In the Raman spectra, there were two lines due to cBN at 1054.5 and... 

Connected with the advancement of synthetic diamond as a technical material, cubic boron nitride (cBN) has attracted increasing interest during the past decades. 

Following the successful commercial synthesis of diamond in the 1950s, the second hardest material known, cubic boron nitride, cBN, was introduced to the market in the 1960s and is complementary to diamond. The iron, and its alloying elements, in ferrous materials has a tendency to react chemically with diamond under machining conditions and this can reduce the efficiency of the tool. cBN, however, although not as hard as diamond, does not react chemically with iron and is therefore particularly well suited to machining hard ferrous materials. 

High-performance abrasive grains (diamond, cubic boron nitride (CBN))... 

The invention of cubic boron nitride (CBN) is closely linked to the synthesis of artificial diamond. Cubic boron nitride synthesis was conducted first in 1957. CBN crystals are produced from boron and nitrogen at high pressures of 50-90 kbar, high temperatures between 1,800 °C and 2,700 °C, and in the presence of a catalyst (Klocke 2009). During the first years on the market, CBN was seen as a competitor to diamond. However, CBN proved to be a better material for machining of hard-to-machine ferrous materials than diamond due to the missing chemical affinity and the higher thermal stability. 

Cubic boron nitride (CBN) has superior thermochemical stability compared to diamond. Ultrafine-crystalline CBN (CBN-U) is a special type of CBN, which has a grinding ratio that is eight times higher, and a higher wear resistance than conventional CBN (Chen et al. 2002). For grinding of ferrous components and other materials that react with diamond, cubic boron nitride is the best choice. 

Rg. 3.2-2a,b Temperature dependence of (a) the hardness and (b) the thermal condnctivity of ceramic materials in comparison with diamond and cubic boron nitride (CBN) [2.3]... 

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