金刚石摩擦化学抛光用抛光盘制备及抛光机理研究

发布时间：2018-05-14 06:52

本文选题：金刚石 + 摩擦化学抛光　；参考：《大连理工大学》2016年博士论文

【摘要】：金刚石不仅是目前世界上已知材料中最硬的物质,同时也是一种兼备多种优越的物理化学特性的高性能材料,具有很小的摩擦系数、优异的导热性能、优良的电绝缘性、较宽的透光波段、优秀的半导体特性和极强的化学惰性,所以不仅广泛应用于军事国防、航空航天等高精尖的专业领域,而且在超精密加工领域也具有广阔的应用前景。随着人造金刚石的成功研制,金刚石的使用在宽度与深度上都获得了突飞猛进的发展。无论是天然金刚石还是人造金刚石,在实际应用中都需要对其进行精密超精密加工,以使其达到各种使用要求。但是金刚石独特且优良的性能势必将给其精密超精密加工造成极大的困难,已成为限制金刚石得到大量实际应用的技术瓶颈之一,亟待解决金刚石晶体材料的高效精密超精密加工难题。现有的多种金刚石材料抛光方法,无论是物理去除法还是化学去除法、接触式还是非接触式,都存在着各自的优缺点,在抛光机理、抛光速率、尺寸限制和设备要求等方面都有着很大的区别。摩擦化学抛光技术是一种利用机械和化学的协同作用促进金刚石石墨化,实现金刚石材料高效去除的新方法。与传统的热化学抛光技术相比,该方法由于借助机械摩擦生热的方式促进金刚石石墨化,因此不需要加热设备,以及真空或者密闭性保护气氛,大大降低了对专用抛光设备的技术要求,是一种非常有发展前途的金刚石抛光方法。由于摩擦化学抛光技术具有高效低损伤去除的特点,在以高效去除为主要目标的金刚石晶体材料的粗加工领域具有很好的应用前景。但由于目前有关摩擦化学抛光用抛光盘的制备与抛光机理的研究相对较少,该技术在抛光效率和抛光表面质量等方面还存在诸多问题。本文针对金刚石摩擦化学抛光技术中存在的问题,提出了新型合金抛光盘配方,研究了抛光盘制备及金刚石晶体摩擦化学抛光过程中的关键技术及其相关理论,主要研究内容如下：(1)为了在摩擦化学抛光中提高金刚石去除率,同时减小抛光盘的磨损率,需要研制一种兼备极强金刚石石墨化催化能力与良好理化特性的合金抛光盘。根据摩擦化学抛光材料去除原理和过渡金属未配对d电子催化理论,并结合摩擦化学抛光技术对抛光盘材料特性的要求,设计了Fe基、Ni基、Mn基和W基四类共七种合金抛光盘配方。通过研制抛光盘并进行抛光性能对比实验发现,WMoCr合金抛光盘的综合性能最佳,金刚石材料去除率达1.5μm/min,而抛光盘的磨损率仅为0.35 mm3/min,磨削比达23.06。在此基础上,通过对合金添加稀土Y元素等措施,进一步完善了WMoCr合金的微观组织,提升了抛光盘的抛光性能。(2)为了提高抛光盘的综合性能,在WMoCr合金抛光盘的制备过程中,首先利用机械合金化方法获得预合金化良好的合金粉末,再采用真空热压烧结技术制得具备较高硬度和致密度的合金抛光盘。通过机械合金化工艺试验,研究了机械合金化过程中的球磨参数对粉末性能的影响规律,得到了合理的工艺参数：球磨转速为300rpm,球磨时间为60小时,球料比为15:1和PCA含量为10%,制备了晶粒细小、组织性能优异的预合金化粉末,为提高抛光盘的抛光性能提供了保障。在此基础上,通过真空热压烧结试验,研究了烧结温度、烧结压力和保温时间等因素对致密度、硬度等合金材料性能的影响规律。结果表明,在烧结温度1400℃、烧结压力30 MPa、保温时间30 min的条件下,所制备的WMoCr合金的性能最佳,硬度达777.78 HV、致密度达96.49%,合金材料的晶粒均匀细小、组织结合紧密而且孔隙率极小(3)利用化学反应热力学吉布斯能变原理讨论了压力和温度对金刚石石墨化平衡常数的影响规律及加快反应的措施,并以此为依据,在搭建的摩擦化学抛光盘抛光性能实验台上,设计了金刚石晶体材料摩擦化学抛光的单因素实验,优选了合理的抛光工艺参数。实验结果显示,抛光压力65 N、抛光速度8000 rpm的条件下,可以实现金刚石高效率高表面质量加工,同时抛光盘的磨损率和氧化程度最低。(4)通过对摩擦化学抛光实验过程观察与反应产物成分的检测分析,并结合化学反应热力学的基本原理,研究了金刚石摩擦化学抛光机理。通过分析抛光前后金刚石与抛光盘表面的化学成分与内部组织的变化,研究了金刚石晶体在摩擦化学抛光中的石墨化转化过程,发现了采用WMoCr合金抛光盘时特有的材料去除机理,即：除了基于石墨化与扩散作用的材料去除外,还通过金刚石相碳与中间产物W03发生化学反应生成WC来实现材料去除。(5)在以上工作基础上,采用自行研制的WMoCr合金杯形砂轮,进行了金刚石晶体的摩擦化学抛光实验,并与传统金刚石砂轮的对金刚石晶体的加工效果进行对比分析,实验结果表明采用WMoCr合金杯形砂轮时,可获得更高的材料去除率和表面质量。最后采用自行研制的WMoCr合金抛光盘探索了金刚石砂轮的修整方法,分析其可行性与修整效果。
[Abstract]:Diamond is not only the most hard material known in the world at present, but also a high performance material with a variety of superior physical and chemical properties. It has very small friction coefficient, excellent thermal conductivity, excellent electrical insulation, wide transmittance, excellent semiconductor characteristics and very strong chemical inertness, so it is not only widely used. The pan should be used in military defense, aerospace and other high-precision fields, and it also has broad application prospects in the field of ultra precision processing. With the successful development of artificial diamond, the use of diamond has developed rapidly in width and depth. It is necessary to make precision ultra precision machining to make it meet various requirements. However, the unique and excellent performance potential of diamond will cause great difficulty for its precision ultra precision machining. It has become one of the technical bottlenecks to limit the practical application of diamond, and it is urgent to solve the high efficiency and precision of diamond crystal material. Many of the existing polishing methods for diamond materials, whether physical removal or chemical removal, contact or non-contact, have their own advantages and disadvantages. There are great differences in polishing mechanism, polishing rate, size limitation and equipment requirements. The friction chemical polishing technology is a kind of use machine. The synergistic action of weapons and chemistry promotes the graphitization of diamond and realizes the new method of high efficiency removal of diamond materials. Compared with the traditional thermo chemical polishing technology, this method promotes the graphitization of diamond with the aid of mechanical friction and heat generation, so it does not need heating equipment, vacuum or closed protective atmosphere, which greatly reduces the effect. The technical requirements of special polishing equipment are a very promising diamond polishing method. Because of the characteristics of high efficiency and low damage removal, the friction chemical polishing technology has a good prospect in the field of rough machining of diamond crystal materials with high efficiency as the main target. The research on the preparation and polishing mechanism of the discs is relatively less. There are still many problems in the polishing efficiency and the quality of the polishing surface. In this paper, a new type of alloy discs formula is put forward in view of the problems in the diamond friction chemical polishing technology. The preparation of the discs and the friction chemical polishing of diamond crystals are studied. The key technology and related theories in the process are as follows: (1) in order to improve the diamond removal rate in the friction chemical polishing and reduce the wear rate of the discs, a kind of alloy discs with good catalytic ability and good physicochemical properties is needed to be developed. The theory of d electron catalysis is not matched with the transition metal, and the requirements of the friction chemical polishing technology to the properties of the discs are designed. A total of seven kinds of alloy discs are designed for the four kinds of alloys, such as Fe, Ni, Mn and W. By developing the discs and comparing the polishing performance, it is found that the comprehensive performance of the WMoCr alloy discs is the best. The removal rate of the material is 1.5 m/min, and the wear rate of the discs is only 0.35 mm3/min, and the grinding ratio is up to 23.06.. By adding the rare earth Y element to the alloy, the microstructure of the WMoCr alloy is further improved and the polishing performance of the discs is improved. (2) in order to improve the comprehensive performance of the discs, the preparation of the discs of the WMoCr alloy is made. In the process, the good alloy powder prealloyed by mechanical alloying is obtained first, and then the alloy discs with high hardness and density are obtained by vacuum hot pressing and sintering. Through the mechanical alloying process test, the influence law of ball milling parameters on the properties of the powder in the process of mechanical alloying is studied. The process parameters: the ball milling speed is 300rpm, the ball milling time is 60 hours, the ball material ratio is 15:1 and the PCA content is 10%. The pre alloyed powder with fine grain and excellent microstructure and properties is prepared. On this basis, the sintering temperature, the sintering pressure and the guarantee are studied through the vacuum hot press sintering test. The effect of temperature time and other factors on the properties of alloy materials such as density and hardness, and the results show that, under the conditions of sintering temperature 1400 C, sintering pressure 30 MPa and holding time 30 min, the properties of the prepared WMoCr alloy are the best, the hardness is 777.78 HV, the density is 96.49%, the grain size of the alloy material is even fine, the microstructure is tightly combined with the hole. The gap rate is very small (3) the effect of pressure and temperature on the equilibrium constant of the graphitization of diamond and the measures to expedite the reaction are discussed by the principle of chemical reaction thermodynamics Gibbs energy change. On this basis, a single factor of friction chemical polishing of diamond crystal material is designed on the experimental table of friction chemical polishing disc polishing performance. The experimental results show that the reasonable polishing process parameters are optimized. The experimental results show that the high efficiency and high surface quality processing of diamond can be achieved with the polishing pressure of 65 N and the polishing speed of 8000 rpm, and the wear rate and oxidation degree of the discs are the lowest. (4) detection and analysis of the composition of the reaction products by the experimental process of friction chemical polishing. On the basis of the basic principle of chemical reaction thermodynamics, the mechanism of diamond friction chemical polishing was studied. By analyzing the chemical composition and internal structure of the surface of diamond and discs before and after polishing, the transition process of the graphitization transformation of diamond crystal in the friction chemical polishing was studied, and the characteristic of using WMoCr alloy discs was found. The material removal mechanism is: except for the material based on the graphitization and diffusion, the chemical reaction of the diamond phase carbon and the intermediate product W03 is also produced to produce WC to realize the material removal. (5) on the basis of the above work, the friction chemical polishing experiment of the diamond crystal was carried out by using the self developed WMoCr alloy cup wheel. Compared with the traditional diamond grinding wheel, the processing effect of diamond crystal is compared and analyzed. The experimental results show that higher material removal rate and surface quality can be obtained when WMoCr alloy cup grinding wheel is used. Finally, the self developed WMoCr alloy discs are used to explore the dressing method of diamond wheel, and the feasibility and dressing effect is analyzed. Fruit.

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ163

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