碳纳米葱添加cBN及碳纳米管的高温高压烧结与组织研究

发布时间：2018-03-18 18:32

  本文选题：碳纳米葱　切入点：立方氮化硼　出处：《燕山大学》2015年硕士论文　论文类型：学位论文

【摘要】：金刚石是世界上硬度最高的材料,并且具有极高的热导系数,但由于金刚石的热稳定性差,金刚石工具在高温环境下工作会发生严重的热磨损。聚晶立方氮化硼热稳定性较好,并且是公认的切削黑色金属和高硬度碳化物的最好材料,而金刚石工具却完全不能加工上述材料,但聚晶立方氮化硼的维氏硬度较低,仅为33~45 GPa。本论文首次将碳纳米葱(OLC)与立方氮化硼(cBN)混合后在高温高压条件下烧结,旨在研究一种金刚石和立方氮化硼的复合材料,使其耐热性、耐磨性,硬度和断裂韧性等物理性能更加优异,研究cBN的添加量、烧结条件和cBN颗粒表面状态对OLC-cBN烧结体组织和性能的影响。对烧结样品进行XRD、FESEM、HRTEM和维氏硬度分析,最终得出,烧结效果较为理想的工艺条件是加入30wt.%的cBN,烧结压力为6 GPa,温度为1300℃,保温时间为15 min,此时OLC-cBN烧结体硬度为36.66 GPa,OLC向金刚石的转化率为46.66%,合成的聚晶金刚石和添加的cBN颗粒间结合的非常紧密。本论文将OLC与多壁碳纳米管(MWCNT)混合后在高温高压下烧结,旨在通过这种方法降低OLC向金刚石转变的温度、提高OLC转化率,并且优化混合烧结体的性能,研究烧结条件对OLC-MWCNT烧结体的组织和性能的影响,最终得出,加入MWCNT质量分数为10%时,最佳工艺条件为:烧结压力5.5 GPa,温度1150℃,保温时间20 min,该条件下,烧结体硬度为18.84 GPa,OLC向金刚石的转化率为25.96%。
[Abstract]:Diamond is the highest hardness material in the world, and it has very high thermal conductivity. However, due to the poor thermal stability of diamond, diamond tools will suffer serious thermal wear in high temperature environment, and polycrystalline cubic boron nitride has good thermal stability. And is recognized as the best material for cutting ferrous metals and high-hardness carbides, but diamond tools can't process them at all, but polycrystalline cubic boron nitride has lower Vickers hardness. In this paper, the carbon nano-scallion (OLC) and cubic boron nitride (cBN) were mixed for the first time and sintered under high temperature and high pressure. The purpose of this paper is to study a kind of diamond and cubic boron nitride composite material, which can make it heat-resistant and wear-resistant. The physical properties such as hardness and fracture toughness are more excellent. The effects of the addition of cBN, sintering conditions and the surface state of cBN particles on the microstructure and properties of OLC-cBN sintered body are studied. The optimum sintering conditions are as follows: adding 30 wt.% cBN, sintering pressure 6 GPA, temperature 1300 鈩，

本文编号：1630797