Preparation And Performance Study Of Cubic Boron Nitride-Boron Carbide Compositeunder High Tempreature High Pressure

Cubic boron nitride has become a core superhard material with high attention due to its high hardness,high thermal stability and good chemical stability.It is used in important fields such as industry,science and technology,national defense and aerospace.It is not easy to react with iron group element materials,and is widely used as tools and abrasives to process iron alloy materials that diamond cannot process.The cubic boron nitride composite is a functional composite ceramic with high density and strong hardness.At present,China’s self-produced cubic boron nitride products generally have the disadvantages of low toughness,low density and poor wear resistance.In this paper,cBN-B₄C composite ceramics were synthesized under high temperature and high pressure by using boron nitride powder as raw material,adding different proportions of boron carbide as toughening agent,metal aluminum and metal cobalt as sintering additives.The effects of temperature,pressure and doping concentration on the properties of composite ceramics were investigated.The results of this study show that:（1）When the synthesis pressure is 5.7 GPa,8wt%Al and 2wt%Co are added for bonding.Under the condition that the molar mass ratio of cBN to B₄C is 9:1,the density and wear ratio of cubic boron nitride composite ceramics increase first and then decrease with the increase of temperature.（2）When the pressure is 5.7 GPa and the temperature is 1450°C,with the increase of B₄C doping concentration,the crystal quality of the synthesized cubic boron nitride-boron carbide composite sheet decreases,and the toughness and wear resistance also decrease.（3）The introduction of boron carbide enhances the fracture toughness and wear resistance while maintaining high hardness.The prepared samples have high density and better wear resistance than before,and the comprehensive performance is excellent.