【作者】 王立；

【导师】 李嫚；

【作者基本信息】 大连理工大学 ， 机械电子工程， 2008， 硕士

【摘要】 PDC复合片(Polycrystalline Diamond Compact，简称PDC)的焊接是聚晶金刚石刀具制作的关键工序。高频感应钎焊凭借其环境污染小、生产效率高等优点成为目前世界各国主要采用的PDC刀具焊接方法。但是由于PDC复合片的钎焊工艺性差，且国内在这方面的研究和应用起步比较晚，与国外相比有较大差距，在国内的生产实践中经常会出现PDC复合片与刀具基体结合强度低，所焊刀具出现脱片现象。因而，为了尽快提高国产PDC刀具的制作水平，有必要对影响PDC刀具高频感应钎焊质量的因素进行系统、全面的研究。本文刀具基体材料选用45#钢和YG8硬质合金，使用GP15-CW6型高频感应焊机，在空气氛围下对PDC复合片进行了钎焊试验。采用自制的剪切力标定装置，同时借助扫描电镜及电子探针等手段研究了焊前处理、钎料、钎剂的搭配、钎焊工艺参数以及焊后冷却对PDC刀具钎焊质量的影响。首先，研究了焊前母材表面处理对焊缝剪切强度的影响，发现PDC复合片表面和刀槽的表面都经过锉削处理时可获得较好性能的PDC刀具钎焊接头，并且试件两钎焊表面锉削方向一致时性能更好。其次，采用石膏粉冷却和空气冷却两种方式对比试验。研究了焊后冷却对刀具性能的影响，认为石膏粉冷却可以阻碍钎焊接头的氧化及裂纹的产生，获得较好的钎焊效果。随后，进行了钎料、钎剂搭配对PDC刀具钎焊性能影响的试验，结果表明：PDC复合片与YG8硬质合金钎焊，采用1#钎料与QJ102钎剂搭配时钎焊接头剪切强度最高，2#钎料与QJ102钎剂搭配方式获得的钎焊接头性能最差；PDC复合片与45#钢钎焊时，2#钎料与F500A钎剂搭配效果最好，1#钎料与F500A钎剂搭配最差。然后对钎焊温度和钎焊压力等钎焊工艺参数进行定量研究，得出以下结论：钎焊温度越高，PDC刀具的剪切强度越大，焊缝厚度越小；为了获得综合性能较好的钎焊接头，PDC复合片与YG8硬质合金刀体的钎焊温度应控制在690℃左右，PDC复合片与45#钢刀体的钎焊温度最好控制在670℃左右；随着钎焊压力的增大，剪切强度先增大后减小，最后基本不变；而焊缝厚度却随着压力的增大而减小，最终趋于定值。最后，探讨了在钎料、钎剂及钎焊工艺参数不变的条件下，一些特殊措施对PDC刀具钎焊性能的影响，认为复焊和用陶瓷棒施加钎焊压力可进一步提高PDC刀具钎焊强度。更多还原

【Abstract】 The polycrystalline diamond compact (PDC)’s brazing is a key procedure of making polycrystalline diamond cutting tools. Nowadays, the high-frequency induction brazing is the main technique used in the PDC’s brazing around the world, due to its notable advantages such as less pollution to environment and higher production efficiency. However, because the PDC has poor brazing processability, and the research and application of the PDC in China still stays at a lower level currently. Compared to other countries, the PDC cutting tools sometimes can break off when it is used in practice for the low brazing intensity between the PDC and base materials. Therefore, it is necessary to investigate the influence factors on the hi-frequency induction brazing technique of PDC in detail as soon as possible, in order to upgrade the performance of PDC cutting tools.The PDC’s brazing experiments were carried out in air atmosphere with two base materials (45# steel and YG8 cemented carbide), using high-frequency induction brazing machine GP15-CW6. The effect of pre-treatment before brazing, the arrangement of braze alloys and soldering flux, brazing parameters and coolant method after brazing on PDC tools’ brazing quality were studied systematically by means of self-made shearing equipment, as well as scanning electron microscopy (SEM) and electronic probe microscopy (EPM).Firstly, the effects of base materials’ surface pre-treatment on the shearing strength of brazing joints were investigated. It was indicated that high-strength brazing joints would be obtained when the surfaces of the PDC and base metal were both filed, and the brazing joint would reach the greatest effect especially when the filing strips on the compacts were aligned with that on base metals surface.Secondly, through comparison experiment with two cooling medium (air coolant and plaster powder coolant), the influence of the cooling on PDC tools’ using performance was analyzed. The results showed that the plaster powder cooling could restrain brazing joints of PDC cutting tools from oxidation and microcracks, so the effect of the plaster powder cooling was much better than that of the air coolant.Subsequently, the effect of braze alloy and soldering flux matching in pairs on brazing performance was investigated, using two different braze alloys (1#、2#) and two different soldering fluxes (QJ102 and F500A). It was founded that the best brazing joint of the PDC and YG8 cemented carbide could be acquired in arrangements of braze alloy 1# and soldering flux QJ102, and the worst one was the compounding of braze alloy 2# and soldering flux QJ102. On the other hand, for the brazing of PDC and 45# steel, braze alloy 2# and soldering flux F500A was the best arrangement, while the braze alloy 1# with soldering flux F500A was the worst.By means of single factor experiments, the high-frequency induction brazing parameters of PDC tools such as brazing temperature and brazing pressure were analyzed quantitatively later. The results indicated that with the increase of brazing temperature, the shearing strength increased gradually, but the joint width diminished otherwise. To get a better integrated property of brazing joints, it was proposed that the brazing temperature of the PDC compact/ YG8 cemented carbide should be controlled at about 690℃, and the PDC compact/45# steel at 670℃. The results also showed that, with the increase of brazing pressure, the shearing strength increased first, decreased afterward, and became steady after reaching a certain value while the joint width just decreased all along with the increase of brazing pressure and reached a steady value at last.Finally, special technical measures such as the again-brazing technology and applying brazing pressure with ceramic bar were discussed in case of stationary braze alloy and brazing parameters, and they were considered as functional methods with an apparent enhancement of shearing strength of the PCD tools.更多还原