微米金刚石含量对圆葱碳烧结制备聚晶金刚石(PCD)组织及性能的影响

Effect of Microdiamond Content on Microstructures and Properties of PCD Sintered from Onion-like Carbon

以OLC_(11)(1 100℃/0.1 Pa条件下制得的OLC)与微米金刚石为原料,在1 200℃/5.5 GPa/15 min条件下烧结制备了无添加剂聚晶金刚石(PCD),研究了微米金刚石加入量对PCD组织及性能的影响。结果表明:微米金刚石加入量低于50%时,随着微米金刚石加入量增加,OLC11转化的金刚石晶粒尺寸逐渐均匀且越来越大,微米金刚石与OLC_(11)转变的金刚石基体间结合得越好。当微米金刚石含量高于50%时,随着微米金刚石含量增加,微米金刚石与OLC_(11)转变的金刚石基体间不能有效结合,PCD硬度逐渐降低。微米金刚石含量为50%时,PCD硬度及晶粒尺寸最大,分别为44.7 GPa及20 nm。加入适量的微米金刚石可以增强样品内部传压,并作为晶种,提高OLC转化率,提升PCD性能。

With microdiamond（ MD） and OLC11,an onion-like carbon（ OLC） synthesized by annealing detonation nanodiamond in chamber with vacuum degree of 0. 1 Pa at 1 100 ℃,as raw materials,additive-free nanoscaled polycrystalline diamond（ PCD） was prepared by sintering for 15 min at 1 200 ℃ and 5. 5 GPa. The studies on the influence of MD content on microstructures and properties show that,with MD content of less than 50%,diamond grains transformed from OLC11 became gradually larger in size and more homogeneous in distribution with the increased MD content,meanwhile,the bonding between MD and diamond matrix became more intensive. While,with MD content over50%,the hardness of PCD declined owing to the less effective bonding between MD and diamond matrix with an increase in MD content. After processed with MD content of 50%,PCD hardness and grain size attained the maximum value,respectively at 44. 7 GPa and 20 nm. A moderate addition of MD grains can enhance the internal pressure transmission,increase the OLC transformation rate as seed crystals and improve PCD properties.