Nitrides bulk components

Hard materials available for the production of bulk components fall into two major groups hard metals , used primarily in the manufacture of cutting tools and related applications, and structural ceramics, primarily the oxides, carbides, borides, or nitrides of the low atomic number cations. Relatively few materials are of engineering importance, and we will list these, explaining briefly why similar compositions are less useful. 

Bulk isotopic compositions of chondrites. Isotopic compositions of bulk chondrites are essentially uniform within variations of 0.1-0.01% except for light elements such as H, C, N, and O and for presolar grains (see e.g. Lodders 2003 Palme Jones 2003). Presolar grains have isotopic compositions significantly different from those of Solar System materials, suggesting that they were dust particles formed in circumstellar environments and incorporated into the proto-solar molecular cloud (Chapter 2 and see e.g. Nittler 2003 Zinner 2005). Presolar grains are thus considered to be the first dust components that formed in the proto-solar disk. The rarity of presolar grains in chondrites (several ppb for silicon nitride to 200 ppm... 

The dimensions of the added nanoelements also contribute to the characteristic properties of PNCs. Thus, when the dimensions of the particles approach the fundamental length scale of a physical property, they exhibit unique mechanical, optical and electrical properties, not observed for the macroscopic counterpart. Bulk materials comprising dispersions of these nanoelements thus display properties related to solid-state physics of the nanoscale. A list of potential nanoparticulate components includes metal, layered graphite, layered chalcogenides, metal oxide, nitride, carbide, carbon nanotubes and nanofibers. The performance of PNCs thus depends on three major attributes nanoscopically confined matrix polymer, nanosize inorganic constituents, and nanoscale arrangement of these constituents. The current research is focused on developing tools that would enable optimum combination of these unique characteristics for best performance of PNCs. 

Finally, we will show that this innovative processing route can be extended to the production of bulk ceramic components by pyrolysis in reactive atmosphere, such as for example, production of SiAlON ceramics by nitridation of PAIC in ammonia flow [75]. 

CVD is a versatile process, well adapted to the production of all the refi actory carbides and nitrides not only as coatings but also as powders, bulk/monolithic components, and fibers. It may be defined as the deposition of a solid on a heated surface firom a chemical reaction in the vapor phase. Its advantages are ... 

This is the first book devoted to the theoretical modelling of refractory carbides and nitrides and alloys based on them. It makes use of computational methods to calculate their spectroscopic, electric, magnetic, superconducting, thermodynamical and mechanical properties. Calculated results on the electronic band structure of ideal binary transition-metal carbides and nitrides are presented, and the influences of crystal lattice defects, vacancies and impurities are studied in detail. Data available on chemical bonding and the properties of multi-component carbide- and nitride-based alloys, as well as their surface electronic structure, are described, and compared with those of bulk crystals. 

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