Titanium boride

Titanium diboride

Identifiers
CAS Number	12045-63-5 Y
ECHA InfoCard	100.031.771
Properties
Chemical formula	TiB2
Molar mass	69.489 g/mol
Appearance	non lustrous metallic grey
Density	4.52 g/cm3
Melting point	3,230 °C (5,850 °F; 3,500 K)
Structure
Crystal structure	Hexagonal, Space group P6/mmm. Lattice parameters at room temperature: a=302.36 pm, C=322.04 pm
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Titanium diboride (TiB₂) is an extremely hard ceramic which has excellent heat conductivity, oxidation stability and resistance to mechanical erosion. TiB₂ is also a reasonable electrical conductor, so it can be used as a cathode material in aluminium smelting and can be shaped by electrical discharge machining.

TiB₂ is very similar to titanium carbide, an important base material for cermets, and many of its properties (e.g. hardness, thermal conductivity, electrical conductivity and oxidation resistance) are superior to those of TiC:

With respect to chemical stability, TiB₂ is more stable in contact with pure iron than tungsten carbide or silicon nitride.

TiB₂ is resistant to oxidation in air at temperatures up to 1100 °C, and to hydrochloric and hydrofluoric acids, but reacts with alkalis, nitric acid and sulfuric acid.

TiB₂ does not occur naturally in the earth. Titanium diboride powder can be prepared by a variety of high-temperature methods, such as the direct reactions of titanium or its oxides/hydrides, with elemental boron over 1000 °C, carbothermal reduction by thermite reaction of titanium oxide and boron oxide, or hydrogen reduction of boron halides in the presence of the metal or its halides. Among various synthesis routes, electrochemical synthesis and solid state reactions have been developed to prepare finer titanium diboride in large quantity. An example of solid state reaction is the borothermic reduction, which can be illustrated by the following reaction