Physical transition metal carbides/nitrides

Transition metal carbide, nitride and carbonitride layers of the IVB group made by CVD (chemical vapor deposition) and PVD (physical vapor deposition) are produced in order to increase the service life of hardmetal tools [18,21,108] for cutting and milling operations. About 90% of cutting tools are coated. 

T Epicier. Application of transmission electron microscopy to the study of transition metal carbides, nitrides and borides. In The Physics and Chemistry of Carbides, Nitrides and Borides. R Freer, ed. Dordrecht Kluwer Academic, 1990, p 297. 

This volume, which is unique in its coverage, provides a general introduction to the properties and nature of transition metal carbides and nitrides, and covers their latest applications in a wide variety of fields. It is directed at both experts and nonexperts in the fields of materials science, solid-state chemistry, physics, ceramics engineering and catalysis. The first chapter provides an overview, with other chapters covering theory of bonding, structure and composition, catalytic properties, physical properties, new methods of preparation, and spectroscopy and microscopy. 

In contrast to the physical properties, transition metal carbides and nitrides possess electric and magnetic properties that are often similar to metals. For example, electrical resistivities of Ti or W are 39 and 5.39 pft cm at room temperamre, while their respective carbides have only slightiy higher resistivities of 68 and 22 p,fl cm. For comparison the electrical resistivity of the hard SiC ceramics is significantly higher (1000 pfi cm). 

Which physical property makes transition metal carbides and nitrides a good component for cutting tools In this respect why is cobalt used as a matrix material for their sintering ... 

This book presents a systematic description of the electronic and physicochemical properties of transition-metal carbides and nitrides. These materials possess remarkable physical and chemical properties, including extremely high hardness and strength, and high melting points, metallic conductivity and superconductivity. As a result, they have been extensively studied by scientists, and their properties widely exploited by engineers. 

Table 3.1 summarizes some physical properties of transition-metal carbides and nitrides. 

The transition metal monocarbides and mononitrides typically exhibit wide homogeneity regions, caused by the formation of vacancies, mainly on the nonmetal sites and, to a much lesser extent, also on the metal sites. Because the vacancies have a strong influence on the physical and chemical properties of the substances, a large number of theoretical and experimental investigations have been devoted to the study of the electronic structure of vacancy-containing transition metal carbides and nitrides. 

Billingham, J., Bell, P. S., Lewis, M. H. (1972). Vacancy Short-Range Order in Sub-stoichiometric Transition Metal Carbides and Nitrides withNaCl Structure. I. Electron Diffraction Studies of Short-Range Ordered Corrpounds. Acta Crystallographica. Section A, Crystal Physics, Diffraction, Theoretical and General Crystallography, 28, 602-606. doi 10.1107/S0567739472001524. 

Carbides and nitrides based on the transition metals of Groups 4 through 6 of the Periodic Table have a number of special physical and mechanical properties that make them attractive for use in engineering applications. This paper discusses these properties and how they are exploited in cemented carbides and carbonitrides used in metalcutting and nonmetalcutting applications. 

The interstitial structures comprise the compounds of certain metallic elements, notably the transition metals and those of the lanthanide and actinide series, with the four non-metallic elements hydrogen, boron, carbon and nitrogen. In chapter 8 we discussed the structures of a number of hydrides, borides, carbides and nitrides of the most electropositive metals, and these we found to be typical salt-like compounds with a definite composition and with physical properties entirely different from those of the constituent elements they are generally transparent to light and poor conductors of electricity. The systems now to be considered are strikingly different. They resemble... 

TABLE 5.2 Physical and Chemical Properties of Common Transition Metal Nitrides and Carbides... 

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