Rhenium Diboride Powder

The production method of this material does not involve high pressures as with other hard synthetic materials, such as cubic boron nitride, which makes production cheap. However, rhenium itself is an expensive metal.

The compound is formed from a mixture of rhenium, noted for its resistance to high pressure, and boron, which forms short, strong covalent bonds with rhenium.

Chemical Formulas: ReB2

1) Two factors contribute to ReB2's excellent hardness: a high-density of valence electrons and an abundance of short covalent bonds. In chemistry, valence electrons are the electrons in the outermost shell. Rhenium has one of the highest valence electron densities among any transition metal (476 electrons/nm3, as compared to 572 electrons/nm3 for osmium and 705 electrons/nm3 for diamond). Osmium is a chemical element with the symbol Os and Atomic number 76. The addition of boron requires only a 5% expansion of the rhenium lattice because the small boron atoms fill the existing spaces between the rhenium atoms. Furthermore, the electronegativities of rhenium and boron are close enough. "Electronegativity" is the opposite of "Electropositivity," which describes an element's ability to donate electrons 9 and 2. 04 on the Pauling scale) that they form covalent bonds in which the electrons are shared almost equally.