| 摘要 |
PURPOSE:To produce fine powder of boron carbide of <=1mu in diameter and having round shape and high purity, by reacting finely crushed hexagonal boron nitride powder with fine carbon powder at a high temperature. CONSTITUTION:Fine powder of boron carbide can be produced by reacting finely crushed hexagonal boron nitride powder with fine carbon powder at a high temperature. The hexagonal boron nitride used as a starting material preferably has high purity (>=99.5%) and a particle diameter of about 2-5mu. The reaction temperature is 1,900-2,200 deg.C, preferably 2,000-2,050 deg.C. When the reaction temperature is lower than the above range, there is no formation of B4C, and when the temperature exceeds the upper limit, sintering of produced B4C particles takes place. Agglomerated fine particles, if any, can be disintegrat ed by lightly crushing again in a ball mill, etc. The particle diameter of the mixed powder of boron carbide and carbon can be adjusted over a wide range from about 0.02-1.0mu by controlling the extent of crushing of BN used as a raw material. |
