Titanium nitride, chemical formula TiN, is a synthetic ceramic material, very hard and its hardness is close to that of diamond. It is commonly used as a coating on titanium alloys, steels, cemented carbide and aluminum structures to improve surface properties. As a thin coating, titanium nitride is used to harden, protect cut and slide surfaces, and can also be used for decorative purposes as well as a non-toxic external medical implant. The coating in most applications is less than 5 microns.
Titanium nitride is chemically stable at room temperature but is attacked by hot concentrated acid and oxidized at 800 ° C at atmospheric pressure. Has the reflection characteristic of infrared ray (IR), the reflection spectrum is similar to the spectrum of gold, so it is pale yellow. Depending on the substrate finish and substrate finish, the relative coefficient of friction of titanium nitride is about 0.4-0.9 (no lubrication). The typical crystal structure is sodium chloride (elemental relative stoichiometry is about 1: 1), while the thermodynamic stability coefficient x of TiNx complex is 0.6-1.2.  The world's first super insulation material is also made of titanium nitride film cooled to near absolute zero temperature, the insulation properties will increase by 100,000 units.
Titanium nitride coatings are widely used on metal edges to maintain the corrosion resistance of mechanical molds, such as drill bits and milling cutters, often by improving the life of three or more factors. Because of its metallic luster, it is often used as a decoration for clothing and car decoration. As the outer coating, usually nickel (Ni) or chromium (Cr) as the substrate, packaging pipes and doors and windows hardware. The coating is also used in aerospace and military aspects, as well as protecting the sliding surfaces of the bicycle and motorcycle suspension, and even remotely controlling the shock shaft of the toy car. Because it is non-toxic and FDA compliant, it is also commonly used in medical devices, such as the sharpness of the edge of a scalpel blade and an orthopedic bone saw blade , or directly as an implanted prosthesis and other medical implants.