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Tantalum Carbide Nanoparticle: Transition metal carbides are in demand for the unique properties resembling with metal and ceramics constituents. These carbides have high hardness, high melting temperature, and high temperature strength. They have been used as hard constituents in metal matrix composites for high temperature applications and as coatings on cutting tools. Among these carbides tantalum carbide is very important and promising example for industrial applications.
Carbide is a compound composed of carbon and a less electronegative element. The carbides of group IV (Ti, Zr, Hf) and group V (V, Nb, Ta) elements have metal-like properties, such as high thermal and electrical conductivity. They are opaque and have a metallic luster. Transition metal carbides are important materials because they possess some desired properties such as corrosion and wear resistance, electronic, magnetic and catalytic characteristics. They have extremely high melting points and are therefore referred to collectively as the “refractory carbides”.
Tantalum Carbide Nanoparticle (TaC) form a family of binary chemical compounds of tantalum and carbon with the empirical formula TaC, where x usually varies between 0.4 and 1. TaC is extremely hard, brittle, gold colored metalloid which is of considerable interest because of high melting point (4150 °C). It is refractory ceramic materials with metallic electrical Conductivity. The melting points of tantalum carbides peak at about 3880 °C depending on the purity and measurement conditions.
Tantalum carbide is frequently used in materials engineering due to its high corrosion resistance in aqueous solutions at temperatures up to 247 °C. The bonding between tantalum and carbon atoms in tantalum carbides is a complex mixture of ionic, metallic and covalent contributions, and because of the strong covalent component these carbides are very hard and brittle.
TaC has a micro hardness of 1800 kg/mm2 and an elastic modulus of 285 GPa, whereas the corresponding values for tantalum are 110 kg/mm2 and 186 GPa. Tantalum carbides have metallic electrical conductivity, both in terms of its magnitude and temperature dependence.
Properties of Tantalum Carbide Nanoparticle
Tantalum carbide (TaC) has high hardness, high melting point, high chemical stability, good resistance to chemical attack and thermal shock, and excellent oxidation resistance and corrosion resistance, which makes it very attractive for anti-ablation applications. It is found that the ablation mechanism of throat materials could be divided into three categories: sublimation, oxidation and mechanical abrasion. Addition of TaC into throat materials can effectively depress the oxidation reaction during the ablation process by means of forming tantalum oxides (TaO) to make up for the defects of materials and inhibit further oxidation damage.
On an industrial scale, tantalum carbide has primarily been produced by the carbothermal reduction of Ta2O5 with carbon due to the low cost of raw materials. It has been reported that tantalum carbides can be obtained by heating Ta2O5 at high temperature under high vacuum, and higher temperatures for long time. A fast and complete reaction takes place due to high temperature treatment of TaC, so it also causes coarsening of the carbide grains. The reduction of carbide size generally gives a significant improvement of the mechanical properties. The toughness of ceramics can be increased considerably without sacrificing the hardness by reducing the grain size. Tantalum carbide is added to some grades of cemented carbides to make hard carbide cutting tools which have a low coefficient of friction and a high resistance to mechanical shock.
Applications of Tantalum Carbide Nanoparticle (TaC)
They are suitable to cut a variety of materials such as gray cast iron, ductile nodular iron, austenitic stainless steel, nickel-base alloys, titanium alloys, aluminum, free-machining steels, plain carbon steels, alloy steels, and martensitic and ferrite stainless steels. Tantalum and molybdenum carbide coatings are used industrially for wear protection of steel moulds employed in injection cast molding of aluminum and aluminum alloys.
High speed steel tools for machining were coated with TaC by chemical vapor deposition (CVD), and were used in a high speed milling machine. TaC is desirable for market applications such applications as boost rocket motor nozzles that require high thermal-shock resistance. In the commercial sector, TaC has potential application as a material used for cutting tools and wear parts. Tantalum carbide has wide application in biomedical, corrosion, aerospace and electro technology.
TaC stands as a candidate material for next generation thermal heat protection, space aircrafts, automotive wear resistant liners, and propulsion-exposed components. Due to their optical, electronic and magnetic properties, tantalum carbides have been used for optical coatings, electrical contacts and diffusion barriers. Though tantalum carbide (TaC) has been proposed for use as wound filaments in the form of wires, it is prohibited due to the low strength of TaC wires. In the industrial world, it can be used in machining-tool materials to reduce the tendency of welding between steel chips and tool material.