【作者】 陈波；

【导师】 黎明发；

【作者基本信息】 武汉理工大学 ， 物理学， 2009， 硕士

【摘要】 聚晶金刚石复合片(polycrystalline diamond compact,PDC)是以金刚石微粉为原料,WC硬质合金作为基体,通过特定的合成工艺在高温高压条件下烧结而成的一种超硬复合材料。复合片兼具金刚石硬度高、耐磨性好以及硬质合金抗冲击性能强的优点,现已从深井钻探的使用扩大到矿床勘探及机械加工等各个领域,复合片也逐渐取代单晶金刚石成为超硬材料家族中最重要的一员。耐磨性,作为PDC使用的重要特性,一般用磨耗比这个参数来进行表征,PDC生产厂家都在竭尽可能地提高其耐磨性,但是由于影响PDC的耐磨性的因素很多,各因素之间又相互制约,所以进一步提高PDC的耐磨性还存在一些问题。本文利用工具显微镜和磨耗比测试专用砂轮等,研究了PDC耐磨特性的表征,完善了体积磨耗比的测定方法,并与传统的质量磨耗比方法进行了比较。利用扫描电镜研究PDC的微观结构和磨损工作面的显微结构,深入分析了PDC的磨损机理和PDC的微结构对耐磨性的影响,在分析中,初步尝试引入分形原理,利用分形维数计算软件对扫描电镜图像的分形维数进行了计算,试图将其与体积磨耗比建立一定的联系。论文主要工作如下:1.改进了PDC耐磨性的表征方法,以PDC的体积磨耗比取代质量磨耗比。改进后的方案获取数据简便易行,测量数据准确可靠。2.研究了PDC的温度特性。实验显示:当温度升高到一定程度时,PDC的体积磨耗比迅速下降。表明在没有强制冷却的情况下,温度可能是造成PDC失效的主要原因,针对特定的PDC,测定磨耗比的温度特性可以限定其适用范围。3.研究了影响PDC耐磨性的微结构因素,通过扫描电镜分析了粘结剂,晶粒大小及其分布,界面,孔隙对耐磨性的影响,并预测了PDC的磨耗比随微观结构变化的趋势。4.探讨了PDC的磨损机理。利用扫描电镜对PDC磨损断面进行了分析,得出PDC的磨损主要为磨粒磨损,伴随有粘着磨损和疲劳磨损,PDC的磨损过程为金刚石颗粒的微观解理破碎过程,提出了金刚石颗粒的磨损模型。并利用软件计算了磨损断口图像的分形维数,得出磨损面的分形维数在1.5左右。更多还原

【Abstract】 As a type of special composite, Polycrystalline Diamond Compacts (PDC), which use diamond powder as raw materials, WC hard alloy as matrix , in the sintering through specific synthesis process under the conditions of high temperature and high pressure, is a super-hard composite material. PDC has been increasingly applied in machining non-metallic and hard abrasive materials, due to its unique special properties. From the deep well drilling has been extended to the use of exploration and deposit in various fields such as mechanical processing, PDC are gradually replaced by single-crystal diamond as a family of super-hard materials the most important one. Wear resistance, as the use of the key features of PDC, generally we use wear ratio as the characterization parameters of PDC, manufacturers try their best to improve the wear resistance, but there are so many factors that impact wear resistance of PDC, the factors and binding to each other, so to further improve the wear resistance of PDC there are still some problems.In this paper, we used tool microscope and special wheels for the wear ratio test, to study the wear resistant of characteristics of PDC, and improve the determination method of the wear volume ratio and compared it with traditional methods. The use of scanning electron microscopy study of the microstructure of PDC and micro-structure of the wear surface, in-depth analysis of the wear mechanism and micro-structure of PDC, in the analysis, attempt to introduce the fractal theory, the use of fractal dimension calculation software calculated the fractal dimension of the scanning electron microscope image, attempt to establish a certain connection between fractal dimension and wear ratio. The works of the paper are as follows1. On the basis of our predecessors, we improved the method of the characterization of wear resistance. We rather measure the volume wear ratio, than the quality wear ratio of the PDC. Compared with the quality wear ratio, the program improved is simple, credible.2. We have studied temperature characteristic of wear ratio. Experiments show that when the temperature is increased to a certain extent, PDC in the volume wear of PDC rapid decline. Show that in the absence of forced cooling, the temperature may be the main reason for failure of PDC, for the specific PDC, the determination of temperature characteristic of wear ratio. we can limit its scope of application.3. We studied the key factors of the effects of PDC in wear resistance. By scanning electron microscopy analysis of the binder, grain size and distribution, interface, the effects of porosity on the wear resistance, we predict the changes trend of the wear ratio along with the micro-structural.4. We used scanning electron microscopy analysis of the PDC wear section, brought forward the wear model of diamond particles. And we used software to calculate the fractal dimension of the PDC wear section; its fractal dimension is around 1.5. The wear mechanism of PDC is mainly abrasive wear, accompanied by fatigue wear and adhesive wear, the wear process of PDC is the process of cleavage.更多还原