Boron carbide, also known as black diamond, has a molecular formula of B? C and is usually gray black micropowder. It is one of the three hardest materials known (the other two are diamond and cubic phase boron nitride). It is used in tank armor, bullet proof vest and many industrial applications. Its Mohs hardness is 9.3.
It was discovered in the 19th century as a byproduct of the study of metal borides, and was not scientifically studied until the 1930s. Boron carbide can be produced by reduction of boron oxide with carbon in electric furnace.
Boron carbide can absorb a large number of neutrons without forming any radioisotopes, so it is an ideal neutron absorber in the nuclear power plant, and the neutron absorber mainly controls the rate of nuclear fission. Boron carbide is mainly made into controllable rod shape in nuclear reactor field, but sometimes it will be made into powder shape because of increasing surface area.
Because of its low density, high strength, high temperature stability and good chemical stability. It can be used in wear-resistant materials, ceramic reinforced phases, especially in light armor, reactor neutron absorber, etc. In addition, compared with diamond and cubic boron nitride, boron carbide is easy to manufacture and low in cost, so it can be used more widely. In some places, it can replace expensive diamond, and it is commonly used in grinding, grinding, drilling and other aspects.