准晶磨料在软金属表面的研磨特性及其诱发的不锈钢增强钝化效应

发布时间：2018-07-10 02:49

本文选题：Al基准晶 + 研磨　；参考：《大连理工大学》2017年博士论文

【摘要】：准晶材料因其特殊的结构而具有低摩擦系数、低表面能、不粘性、高硬弹比以及高化学和热稳定等特性,在摩擦磨损领域有重要应用价值。本文选用典型的Al_(62.0)Cu_(25.5)Fe_(12.5)二十面体准晶作为磨料,与传统硬质磨料如金刚石、Al_2O_3和SiO_2等进行对比,研究其在研磨金属如铝、铜合金和不锈钢时的摩擦磨损行为,尤其关注准晶独特的碾磨机制,即以极少的表面去除率达到表面平整化,同时揭示了准晶碾磨所带来的特有的不锈钢表面钝化增强效应。本论文的主要研究内容和结论包括如下几点:(1)针对准晶磨料特殊的摩擦磨损方式,建立了相关几何模型,定量描述了准晶磨料对软金属的碾磨主导机制。定义了表征磨损机制的"碾磨系数",表达为表面压痕尺寸变化和表面去除深度的比值△R/△h,碾磨系数越高,说明碾磨作用越占主导地位,反之,则说明切削作用占主导地位。Al_(62.0)Cu_(25.5)Fe_(12.5)二十面体准晶磨料在抛光2024铝合金、T2紫铜、QSn6.5-0.1锡青铜和304不锈钢时始终表现高的碾磨系数,说明了准晶磨料具有突出碾磨作用。(2)准晶磨料的碾磨特性导致金属表面产生强烈硬化效应。Al_(62.0)Cu_(25.5)Fe_(12.5)准晶磨料处理不锈钢表面后,硬度比传统磨料处理的高0.25～0.40GPa,处理紫铜表面,其硬度比传统磨料处理的高0.12～0.21GPa。碾磨机制与传统切削机制比较,准晶磨料在保证加工表面平整性的同时,有效避免表面产生严重的划伤,最大程度的保证加工工件尺寸,符合软金属材料表面抛光的需要。(3)基于准晶磨料特殊的碾磨机制,提出一种区别传统磨料的不锈钢表面预处理方法,可明显提高不锈钢钝化特性和耐蚀性能。利用准晶磨料在平整化金属表面的同时,亦积累大量的塑性变形,增加钝化元素扩散系数形成完整致密的钝化膜,从而有效提高不锈钢耐蚀性能。利用3种传统磨料和准晶磨料预处理304不锈钢样品,进行酸洗钝化处理。在3.5%NaCl中性溶液浸泡不同时间,阻抗EIS测试结果表明,Al_(62.0)Cu_(25.5)Fe_(12.5)准晶磨料处理的不锈钢样品表面阻抗随浸泡时间增加而显著增大。根据等效电路模拟结果,不锈钢内层钝化膜阻抗值在浸泡96 h时达到最大为21.5×105Ω cm~2,比传统磨料预处理的样品高一个数量级。Mott-Schottky结果表明,准晶磨料处理的不锈钢工件的载流子浓度最低,与传统磨料相比,准晶磨料处理的工件表面生成的钝化膜更加完整致密。极化曲线结果表明,随着浸泡时间的增加,准晶磨料抛光的不锈钢表面钝化膜的耐点蚀能力提高。(4)在KOH+NaOH+3.5%NaCl的碱性溶液中,Al_(62.0)Cu_(25.5)Fe_(12.5)准晶磨料处理的不锈钢表面的内层钝化膜阻抗最大为18.543×105Ωcm~2,内层钝化膜的导纳Y2最小,总阻抗值最大。Mott-Schottky结果表明准晶处理的表面钝化膜缺陷最少,在碱性溶液中能够快速地生成比较完整的钝化膜。循环极化曲线结果表明,准晶磨料处理的不锈钢在碱性溶液中能快迅钝化,生成具有较强抗点蚀能力和自我修复能力的钝化膜。上述结果为准晶材料开辟了全新的磨料应用领域,有望形成兼具表面平整化和增强钝化效果的表面处理新方法。
[Abstract]:The quasicrystal material has the characteristics of low friction coefficient, low surface energy, viscosity, high hard elastic ratio, high chemical and thermal stability, because of its special structure. It has important application value in the field of friction and wear. In this paper, the typical Al_ (62) Cu_ (25.5) Fe_ (12.5) twenty surface quasicrystals are used as abrasive and the traditional hard abrasive, such as diamond, Al_2O_3 and SiO, is used. The friction and wear behavior of _2 in grinding metal such as aluminum, copper alloy and stainless steel is studied, especially the unique grinding mechanism of quasicrystals, that is, the surface leveling is achieved with very little surface removal rate. At the same time, the enhancement effect of the specific stainless steel surface passivation caused by the quasicrystal grinding is revealed. The main research content of this paper is the main research content of this paper. And the conclusions are as follows: (1) in view of the special friction and wear mode of the quasicrystal abrasive, a correlative geometric model is established, and the leading mechanism of the grinding of the soft metal is described. The "grinding coefficient" which characterizing the wear mechanism is defined, which is expressed as the ratio of the surface indentation size to the surface removal depth and the ratio of the grinding coefficient, the more the grinding coefficient is, the more the grinding coefficient is obtained. It shows that the grinding effect is the dominant position, and on the contrary, it shows that the cutting action dominated.Al_ (62) Cu_ (25.5) Fe_ (12.5) twenty face quasicrystal abrasive in polishing 2024 aluminum alloy, T2 copper, QSn6.5-0.1 tin bronze and 304 stainless steel. It shows that the quasicrystal abrasive has a prominent grinding effect. (2) quasicrystal abrasive. .Al_ (62) Cu_ (25.5) Fe_ (12.5) pericrystal abrasive has a strong hardening effect on the surface of the stainless steel. The hardness is 0.25 ~ 0.40GPa higher than that of the traditional abrasive. The hardness of the copper surface is compared with the traditional grinding mechanism of the traditional abrasive treatment, which is 0.12 to 0.21GPa., and the quasicrystal abrasive is guaranteed. At the same time, it can effectively avoid serious scratches on the surface and ensure the size of the workpiece to the maximum. (3) based on the special grinding mechanism of the quasicrystal abrasive, a stainless steel surface pretreatment method which distinguishes the traditional abrasive is proposed, which can obviously improve the passivation of stainless steel. When the quasicrystal abrasive is used to smooth the surface of the metal, a large amount of plastic deformation is accumulated while the diffusivity of the passivation element is increased to form a complete and compact passivation film, thus effectively improving the corrosion resistance of stainless steel. 3 kinds of traditional abrasives and quasicrystal abrasives are used to pretreat 304 stainless steel samples to be treated by pickling and passivation. In 3.5 %NaCl neutral solution was soaked for different time. The impedance EIS test results showed that the surface impedance of the stainless steel samples treated with Al_ (62) Cu_ (25.5) Fe_ (12.5) increased significantly with the soaking time. According to the equivalent circuit simulation results, the impedance value of the passivation film in the stainless steel inner layer reached to the maximum of 21.5 x 105 Omega cm~2 when soaking 96 h. The results of a high order of magnitude.Mott-Schottky of the sample prepared by the abrasive pretreatment showed that the carrier concentration of the stainless steel workpiece treated by the quasicrystal was the lowest. Compared with the traditional abrasive, the passivation film formed on the surface of the quasicrystal abrasive was more complete and compact. The polarization curves showed that the polishing of the quasicrystal abrasive was not good as the soaking time increased. Corrosion resistance of the passivation film on the surface of rust steel is improved. (4) in the alkaline solution of KOH+NaOH+3.5%NaCl, the internal passivation film impedance of the stainless steel surface treated by Al_ (62) Cu_ (25.5) Fe_ (12.5) is 18.543 x 105 Omega cm~2, the admittance Y2 of the inner passivation film is the smallest, and the maximum impedance value.Mott-Schottky results show the table of quasicrystal treatment. The surface passivation film has the least defects, which can quickly produce a relatively complete passivation film in the alkaline solution. The cyclic polarization curve shows that the stainless steel treated by the quasicrystal can quickly passivate in the alkaline solution and produce a passivating film with strong resistance to pitting and self repair. The above results have opened a new grinding for the quasicrystal material. In the field of material application, it is expected to form a new surface treatment method with surface smoothness and enhanced passivation effect.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG73

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