以Al、Co、WB为粘结剂高温高压烧结PcBN

PCBN SINTERING WITH AL, CO, WB AS BINDERS UNDER HIGH PRESSURE AND HIGH TEMPERATURE

朱慧雯

11930060

硕士

材料工程

赵予生

2021-05-21

2021-06-11

南方科技大学

深圳

立方氮化硼（cBN）是一种硬度仅次于金刚石的材料。商业上总是将cBN与粘结剂共同烧结成PcBN，不仅能降低合成成本，材料的性能也能得到提高。PcBN超硬刀具在航空航天、机械、汽车等领域有着广泛的应用，它具有硬度高、热稳定性好、较强的化学惰性等优点，能切削有色金属。但目前商业的PcBN的韧性仍然较差，硬度水平也仅约30 GPa左右，导致其使用寿命较短，生产成本增加。本研究通过选取Al、Co、WB为粘结剂、调节粘结剂比例、烧结温度和其它条件，并在5.2 GPa的压力条件下进行烧结，力图改善PcBN的韧性和硬度。其中最硬的PcBN样品达33.1 GPa，在1350 ℃的温度下烧结出来，通过TG和DSC曲线发现，此样品还具有良好的热稳定性。通过XRD的分析，生成物有AlB2、AlN、CoB、W2B5。通过SEM的二次电子图像、背散图像和点扫、面扫，判断了各生成物质的分布和均匀与否。通过几组实验之间的对比，发现当粘结剂的重量比为Co: WB: Al = 6: 2: 7时，效果好于粘结剂重量比为Co: WB: Al = 40: 43: 17时的样品；当钼杯包裹的样品外的传压材料为MgO时，效果好于传压材料为NaCl；当粉末在混合时使用去离子水时，效果好于使用酒精。

Cubic boron nitride (cBN) is a synthetic material whose hardness is second only to diamond. In the commercial industry, cBN is always sintered with binders to form, which can not only reduce the cost, but also improve the properties of materials. PcBN cutting tool is widely used in many fields such as aerospace, machinery and automobile industry. PcBN has the advantages of high hardness, excellent thermal stability and chemical inertia. It can cut ferrous metals too. However, the toughness of commercial PcBN is still poor, the hardness of commercial PcBN only about 30 GPa, and life of the cutting tool short, so as a result the production cost increases. In order to improve the toughness and hardness of PcBN, Al, Co and WB were selected as binders. Ratio of binders, sintering temperature and other conditions were adjusted, and sintering was carried out under the pressure of 5.2 GPa. Among them, the hardest PcBN sample has a hardness of 33.1 GPa, which is sintered at 1350 ℃. From TG curve and DSC curves, it can be seen that the sample has good thermal stability. XRD analysis reveals the products besides cBN are AlB2, AlN, CoB and W2B5. The distribution and uniformity of the products were checked via SEM secondary electron image, backscatter image and EDS. Through the comparison of several groups of experiments, it is found that when the binder weight percent is Co: WB: Al = 6: 2: 7, the effect is better than that when the binder weight percent is Co: WB: Al = 40: 43: 17; When the pressure transfer material outside the molybdenum cup is MgO, the sintering effect is better than that when the pressure transfer material is NaCl; When the powder is mixed with pure water, the effect is better than that of alcohol.

PcBN 硬度 热稳定性 高温高压

PcBN Hardness Thermal Stability HPHT

中文

独立培养

南方科技大学

朱慧雯. 以Al、Co、WB为粘结剂高温高压烧结PcBN[D]. 深圳. 南方科技大学,2021.