Hafnium carbide hardness

Niobium carbide is used as a component of hard metals, eg, mixtures of metal carbides that are cemented with cobalt, iron, and nickel. Along with tantalum carbide, niobium carbide is added to impart toughness and shock and erosion resistance. The spiraling rise in the price of tantalum has spurred the development of a hafnium carbide—niobium carbide substitute for tantalum carbide (68). These cemented carbides are used for tool bits, drill bits, shovel teeth, and other wear-resistant components turbine blades and as dies in high pressure apparatus (see Carbides). 

Hafnium carbide (HfC) This alloy has one of the highest melting points of any binary compound (3.890°C). It is extremely hard and resists corrosion while absorbing slow neutrons. Therefore, it is an ideal metal in the manufacture of control rods for nuclear reactors. 

Hafnium carbide has an extremely high melting point (3887 °C) and may find use as an alternative to tantalum carbide in the production of very hard metal components.28... 

Hafnium carbide has a melting point of 3890°C and exhibits extreme hardness and good electrical conductivity. It is used as an oxidation-resistant coating for composites and as a coating for superalloys [10]. The material is prepared by the CVD of a mixture of hafnium tetrachloride, methane and hydrogen [193, 194]. 

For the CVD processes organometalhc hafninm compounds are often used. Thus, thin films of hafnium carbide were obtained in a planar reactor from bis(cycl-opentadienyl)dimethylhafhium, (ii -C5H5)Hf(CH3)2 as precursor [11]. The carbon content ranged from 11 to 40 weight % and increased with the deposition rate. The film hardness varied between 1,300 and 2,000 HK. 

Hafnium is a metal that closely resembles zirconium. Because the element has a good absorption cross-section for thermal neutrons, almost 600 times that of zirconium, it may be used for nuclear reactor control rods. Hafnium carbide and hafnium nitride are very hard and wear resistant. 

The nitrides and carbides of titanium and zirconium and the carbide of hafnium are extremely hard substances, resembling metals both in appearance and in electrical conductivity. Their formulae approach AxBh but some departure from stoichiometry is possible. Each of these refractory substances has the sodium chloride structure, described alternately (p. 190) as cubic close-packed arrays of metal atoms with the small nonmetal atoms in the octahedral holes. Note, however, that the parent metals themselves do not have cubic close-packed structures. Thus, the older view of such nitrides and carbides as lattices of the parent metals that are expanded to accommodate nitrogen or carbon atoms in the holes (interstices) is not admissible. The nature of the bonding in such refractory nitrides and carbides appears to be linked to the nature of bonding in metals in general, an important and interesting topic, but best pursued in more advanced works. 

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