Titanium carbide

Titanium carbide is a compound of titanium and carbon with the formula TiC. It is a ceramic material, in the form of gray powders or a crystalline solid, black, shiny, extremely hard, 9 to 9.5 on the Mohs scale. It conducts electrical current. It is used in the manufacture of cutting tools.

Properties

Titanium carbide belongs to the so-called interstitial compounds, this allows it to have very good electrical conductivity despite being a ceramic, it has a positive temperature coefficient. The compound structure is formed by carbon atoms embedded in the lattice of the metallic titanium. It has a cubic crystal structure similar to that of sodium chloride with a considerable phase width The composition of the components is often not stoichiometric and ranges from TiC_1.0-TiC_0.3 . or TiC_0.47, according to other authors. This stoichiometric allows spaces of non-metal atoms to remain unfilled. Full occupancy is difficult, not quite achieved TiC_0.98. It is characterized by a particularly high hardness of up to 4000 HV and melts only at a temperature of 3140 °C. It is, however, very fragile. Flexural strength is 240-400 MPa, HV1 hardness 22-30 GPa, and elastic modulus 550-570 GPa. The compound is relatively inert, stable in air up to 800 °C, oxidizes with oxygen to titanium dioxide at a temperature of only around 450 °C. Titanium carbide reacts with nitrogen to form titanium nitride at approximately 1,000°C. Titanium carbide is practically insoluble in water, nor in strongly alkaline solutions. It is insoluble in hydrochloric acid and sulfuric acid, but is soluble in nitric acid and hydrofluoric acid.

Summary

Titanium carbide is generated through physical vapor deposition (PVD) starting from titanium and methane:

Ti+CH4Δ Δ TiC+2H2{displaystyle mathrm {Ti+ CH_{4}longrightarrow TiC+2 H_{2}} }

If chemical vapor deposition (CVD) is used, titanium (IV) chloride and methane are used as starting material:

TiCl4+CH4Δ Δ TiC+4HCl{displaystyle mathrm {TiCl_{4}+ CH_{4}longrightarrow TiC+4 HCl} }

Titanium carbide can also be obtained by carbothermal reduction of titanium dioxide:

TiO2+3CΔ Δ TiC+2CO{displaystyle mathrm {TiO_{2}+3 Clongrightarrow TiC+2 CO} }

It can be obtained by synthesis from the elements or by a growth process similar to that of titanium nitride. In the first reaction it can take place depending on the reaction conditions in air and mixed crystals in the form of carbon titanium nitride TiCN or Titancarboxynitride TICON.

Ti+CΔ Δ TiC{displaystyle mathrm {Ti+Clongrightarrow TiC} }

If an especially pure, stoichiometric composition is desired, a mixture of titanium(IV) chloride, carbon tetrachloride and hydrogen heated to over 1250°C with graphite rods should be used.

TiCl4+CCl4+4H2Δ Δ TiC+8HCl{displaystyle mathrm {TiCl_{4}+CCl_{4}+4 H_{2}longrightarrow TiC+8 HCl} }

Applications

Used as coating material for cutting inserts, milling cutters, drill bits

The chemical industry as an integral part of the sintering of the Ferro-titanite family-material or in general, as a component of acid resistance and stainless steels and hard metals. This is the case with up to 4% of K-group carbide, up to 10% M-group carbide, and up to 43% P-group carbide. Titanium carbide increases high-temperature strength, hardness, and oxidation resistance. Resistance to wear, corrosion and oxidation of tungsten carbide and cobalt base materials can be increased by 6 to 30% thanks to titanium carbide, but at the cost of increasing brittleness, it reduces fracture resistance of the material.

High-speed steel drill bits without the addition of tungsten can be produced by adding nickel-cobalt-based titanium carbide, thereby increasing their cutting speed, accuracy, and better hole finish. surface. It is also used to obtain cermet materials, a hard metal plate that is used for cutting tools.

This material is sometimes referred to as high-tech ceramic, and is used for thermal shielding of spacecraft in Earth's atmosphere.