Boron carbide,a black crystal powder,is one of the hardest man-made materials,its hardness with Mohs hardness 9.36 and micronscopic hardness 5400-6300kg/mm 2 is only near upon diamond,its density is 2.52g/cm 3 and melting point at 2450 ℃ ,the boron carbide possesses properties of edurance hi/low temperature,no reaction with erther acids or alkalis,high grimding efficiency, no magnetism.It is a good replacement of diamond.Boron carbide also possesses the specialty properties of light quality,neuton absorbing,semi-conductivity,etc.so it is used for armed forces and nuclear industry.Boron carbide is widely applied as follows:boriding refractory,ion transfuse,film layer as well as grinding,polishing,drilling hard metal alloys,jewels,etc.Meanwhile,it is main material for the wear-resisting parts,precise meter-age element,precise spray nozzle,sealed washer,smelting boron steel,boron alloy,etc.Boron carbide has showed many better properties of physics and chemistry in the hi-science/technology field.