Aluminium dodecaboride

Aluminium dodecaboride is a superhard chemical compound with 17% aluminium content by weight.
It is the hardest boride of the aluminium-boron system, which also includes,, [Aluminium diboride|] and AlB.

Properties

There are two crystalline forms, α-, and γ-. Both forms are very similar and consist of a framework with three-dimensional networks of and units. The phase β- is now believed to be the ternary boride.

Preparation

The β-form can be prepared by the reaction of boron(III) oxide with sulfur and aluminium, then adding carbon to the mixture.

Uses

The extreme hardness of makes it a favorable component of PCBN inserts, which are mainly used in cutting and grinding to replace diamond or corundum.