What Is Titanium Nitride?
Titanium nitride, a bronze-colored crystalline solid, is produced by heating titanium oxide and carbon in nitrogen or through surface modification via nitrogen plasma treatment on a titanium substrate. Its thin films are known for their gold-like spectral qualities, including infrared reflectivity, which gives them a distinctive yellowish appearance.
Uses of Titanium Nitride
With superior adhesion, wear resistance, corrosion resistance, and heat resistance, titanium nitride serves as an excellent coating material for various tools and equipment, including cemented carbide and cutting tools, as well as food containers and processing equipment. Its attractive golden hue also makes it popular for decorative applications and in the medical field for implants and surgical tools, benefiting from its non-toxic nature.
Properties of Titanium Nitride
Titanium nitride exhibits hardness that is comparable to diamond, showcasing a Vickers hardness of 2,400 and an elastic modulus of 251 GPa. It has a melting point of 2,930°C, a coefficient of thermal expansion of 9.35×10−6K−1, and transitions to a superconductor at 5.6K. Its ability to reflect infrared radiation, resembling gold’s reflective spectrum, contributes to its yellowish tint. The material transitions from a cooper pair insulator to a superinsulator at temperatures near absolute zero, indicating a phase where electrical resistance becomes infinite.
Structure of Titanium Nitride
Titanium nitride (TiN) has a molar mass of 61.874 g/mol and features a sodium chloride-type crystal structure with a 1:1 stoichiometric ratio. Its octahedral coordination structure supports thermodynamically stable TiNx compounds within a range of x=0.6 to 1.2.
Other Information on Titanium Nitride
1. Titanium Nitride in Meteorites
Occurring naturally only in meteorites, titanium nitride is identified as osbornite.
2. Fabrication of Titanium Nitride
Titanium nitride films are primarily produced via physical or chemical vapor deposition. These methods involve sublimating high-purity titanium that reacts with nitrogen in a high-energy vacuum environment or through reactive growth in a nitrogen atmosphere, such as annealing, to form coatings on titanium workpieces.
3. Reaction of Titanium Nitride
While stable at room temperature, titanium nitride begins to oxidize in air at 800℃ and may corrode slowly in concentrated acids at high temperatures. It is slightly soluble in aqua regia, nitric acid, and hydrofluoric acid, but insoluble in water.