Ф25 mm PDC复合材料界面与复合机理研究
INTERFACE STRUCTURE,PROPERTIES AND BONDING MECHANISM OF 25 mm-DIAMETER POLYCRYSTALLINE DIAMOND COMPOSITES
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摘要: 通过超高压高温烧结实验制备了典型界面结构的Ф25 mm PDC复合材料,通过扫描电镜观察分析了PDC样品纵断面上界面附近粘结元素Co的分布;通过剪切和淬火压溃实验测试了典型界面结构的Ф25 mm PDC界面结合强度和界面耐热性能;在实验观察分析的基础上进一步探讨了其界面的复合机理。研究结果表明:随界面的钴含量增高,其结合强度从2.67 GPa增加到2.82 GPa,然后减小到1.47 GPa,但其耐热性能(即检测到样品分层开裂时淬火急冷次数)却分别从15次、11次降低至5次;粗晶粒(180#,80 μ m)界面结合强度和耐热性能分别为0.52GPa和7次,与细晶粒(W10,10 μ m)相比(2.67 GPa,15次)大幅度降低。这表明PDC材料界面性能不仅与界面钴含量及其存在状态有关,而且还与界面晶粒大小相关。Abstract: 25 mm-diameter polycrystalline diamond composites of typical interface structures were sintered in situ under 5.8 GPa at 1500℃ for ３ min by use of different thick cobalt foils as medial layer and different diamond grain sizes. The linear distribution of Co K α (EDW) and characteristic X-ray image of cobalt near the interface was examined by SEM. The bonding strength of the PDC interface was measured by shear test and the heat resistance was measured by the numbers of quench and compression tests. The bonding mechanism of the interface between cemented tungsten carbide and polycrystalline diamond was discussed. The results show that the bonding strength of the PDC interface increased firstly from 2.67 GPa to 2.82 GPa then decreased to 1.47 GPa and the heat resistance decreased from 15, 11 to 5 times separately as the interface cobalt changed from even distribution to high content of cobalt then to cobalt medial layer, compared to the small grain size(10 μm) interface(2.67 GPa, 15 times) the bonding strength and the heat resistance of the coarse grain size(80 μm) interface(0.52 GPa, 7 times) decreased greatly. These indicated that the properties of the PDC interface were depended not only on the content and existential state of the cobalt but also on the grain size of diamond at the interface.
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