B-C-N-Ti四元超硬复合材料的高压烧结

High Pressure Sintering of B-C-N-Ti Quaternary Superhard Composites

以金刚石、立方氮化硼(cBN)和钛(Ti)为初始材料,通过高温高压反应烧结制备了B-C-N-Ti四元超硬复合材料。结果表明:在高温高压下,Ti与金刚石及cBN反应生成TiC_(0.7)N_(0.3)和TiB_(2);TiC_(0.7)N_(0.3)作为黏结相以键合金刚石和cBN晶粒,适量Ti的加入可以有效地提高烧结体的韧性;反应生成的TiC_(0.7)N_(0.3)和TiB_(2)等陶瓷相以及cBN对金刚石晶粒的包裹提高了烧结体的抗氧化性。当金刚石、cBN和Ti的摩尔比为2∶1∶0.10时,在压力为12 GPa、温度为2000℃、保温5 min的条件下得到的烧结样品性能较好,其维氏硬度达到(49.0±1.2)GPa,韧性为(14.2±0.6)MPa·m^(1/2),空气氛围下的起始氧化温度为921℃。

In this work,the B-C-N-Ti quaternary superhard composite was prepared by high pressure and high temperature sintering with diamond,cubic boron nitride(cBN)and titanium(Ti)as starting materials.The characterization results show that Ti reacts with diamond and cBN to form TiC_(0.7)N_(0.3) and TiB_(2) under high pressure and high temperature,which acts as the binding additives for diamond and cBN grains.The addition of appropriate amount of Ti can effectively improve the toughness of the sintered composite specimen.The formation of TiC_(0.7)N_(0.3) and TiB_(2) ceramics and cBN coated the diamond grains and greatly enhanced the oxidation ability.When the molar ratio of diamond,cBN and Ti is 2∶1∶0.10 and sintered at 12 GPa and 2000℃ for 5 min,the specimen exhibits the best performance with Vickers hardness of(49.0±1.2)GPa,fracture toughness of(14.2±0.6)MPa·m^(1/2) and oxidation temperature of 921℃ under air condition.