多相流环境下选矿设备材料的界面损伤行为与机理研究.pdf

博士学位论文 多相流环境下选矿设备材料的 界面损伤行为与机理研究 Research on Interfacial Damage Behaviors and Mechanisms of Mineral Processing Equipment Material under Multiphase Flow Environment 作 者李超永 导 师章新喜教授 中国矿业大学 二〇二〇年七月 万方数据 学位论文使用授权声明学位论文使用授权声明 本人完全了解中国矿业大学有关保留、使用学位论文的规定，同意本人所撰 写的学位论文的使用授权按照学校的管理规定处理 作为申请学位的条件之一， 学位论文著作权拥有者须授权所在学校拥有学位 论文的部分使用权，即①学校档案馆和图书馆有权保留学位论文的纸质版和电 子版，可以使用影印、缩印或扫描等复制手段保存和汇编学位论文；②为教学和 科研目的，学校档案馆和图书馆可以将公开的学位论文作为资料在档案馆、图书 馆等场所或在校园网上供校内师生阅读、浏览。另外，根据有关法规，同意中国 国家图书馆保存研究生学位论文。 （保密的学位论文在解密后适用本授权书） 。 作者签名 导师签名 年 月 日 年 月 日 万方数据 中图分类号 TD923 学校代码 10290 UDC 622.7 密 级 公开 中国矿业大学 博士学位论文 多相流环境下选矿设备材料的 界面损伤行为与机理研究 Research on Interfacial Damage Behaviors and Mechanisms of Mineral Processing Equipment Material under Multiphase Flow Environment 作 者 李超永 导 师 章新喜 申请学位 工学博士 培养单位 化工学院 学科专业 矿物加工工程 研究方向 选矿设备的腐蚀与防护 答辩委员会主席 陶有俊 评 阅 人 二○二○年七月 万方数据 致谢致谢 十年矿大，恍然如梦。惊回首，求学之路，至此而终。忆往昔，感慨万千， 求学艰辛，苦乐相伴。 导师章新喜教授。幸得招募，忝列门墙。导师于我，授之渔鱼。此文凝聚恩 师诸多心血。师惠六载、其渊博的学识、敏锐思维、宽广胸怀、治学理念精益求 精、工作作风求真务实、学术态度一丝不苟，其为人处事之道，明辨是非之理无 不敬佩万分。桃李不言，下自成蹊 朱荣涛副教授明我科研之理，悟学问之道。本文自选题至定稿，章句措辞， 细推严敲， 良工劳心， 历历印心。 师博学谨思， 审问笃行； 每周组会， 必躬亲至； 事无巨细，悉本究末；言传身教，可昭可彰。言之谆谆，教之切切；每思及此， 倍感恩情。而今启程，定从教诲之辞，立德立言，无问西东。 李海生教授，相处六年、亦师亦兄，为师者，点拨迷津，有醍醐灌顶之感； 为兄者，关怀备至，觉感念至深之情。感激之情，难以言表。 学贵得师，亦贵得友。师王艳飞、沈利民、李延锋、孙凤杰、杨海峰。每每 每求教，必倾心相助，指我迷津解我惑。友温晓龙、吴玄培、胡炳涛、陈浙锐， 不辞吝教，指点模型算法，仿真模拟。 独学而无友，则孤陋而寡闻。师门同侪吴开波、何鑫、武涛、杨乃赞、陈玉 坤、史婷、陈晓炜、赵斌、范徐萌、黄鹏飞、刘壮、王贤、王香、马澍、杨胜辉、 董浩然、 王文平。 可谈经论典， 能舞文戏乐； 同舟共济长相伴， 砥砺前行同风雨。 家有椿庭萱堂，已过耳顺之年。灿灿萱草花，罗生北堂下。长我育我，顾我 复我。至于成人，惠泽茂焉，欲报之德，昊天罔极。 恰逢国之盛世，于彭城得殊遇，偶遇新冠疠疾，困敝庐囿作文。幸得国士坐 堂，艰难逆行，坚守寒冬，终迎春辉。 议此文，虽全力以赴，仍有几多尚需推敲。此文亦未逐句练字。知文字无它 术，成文绝非一蹴而就，唯书与文献多读之，亦知万析斧正，方可就梓，诸君之 言，由是感激。 再谢徐州，寄我十年芳华思承恩源，望无愧于所学。 别期将至，离情依依。结余六载，谨为此记。 万方数据 I 摘摘 要要 多相流下选矿设备的界面损伤现象普遍存在于选矿领域， 如冲蚀、 空蚀损伤， 它们是选矿设备用材料破坏或失效的重要原因之一。 每年有巨大数量的钢材被冲 蚀、空蚀消耗，造成惊人的经济损失。湿法选矿工艺中，起泡剂的加入使矿浆环 境更加复杂，过流部件的冲蚀、空蚀损伤更加严重，故有必要对选矿设备材料进 行表面改性，使其具有优异耐磨和耐蚀性能，并对改性后的选矿设备材料的多相 流环境下界面损伤行为和机理进行研究， 以期降低矿用金属材料界面的破坏速率， 延长矿山设备关键零部件的使用寿命。 本文以选矿设备中关键过流部件常用材料 304 奥氏体不锈钢（304 SS）为研 究对象。首先，利用表面超声滚压（SURP）技术对 304 SS 进行表面改性处理， 分别对 304 SS 基体和 SURP 试样进行微观形貌、力学性能、表面电势、钝化膜 状态的表征和电化学性质的测量。结果表明滚压后试样表面维氏硬度和残余应 力增加且部分奥氏体转化成马氏体， 维氏硬度和残余应力的增加有助于减少介质 流动过程中界面因碰撞而产生的划痕和压痕， 奥氏体转变成马氏体的相变可以在 空泡作用下吸收冲击能而避免裂纹扩展， 故试样具有良好的耐磨性。 另外， SURP 304SS 试样表面有晶粒细化的现象， 晶界间表面电势差减小； 同时， 钝化膜中 O、 Cr、Ni 元素的比例增多，Fe 的比例减少，Ni 的富集更为明显，钝化膜中高价态 金属氧化物（CrO3、Ni2O3）和致密性氧化物（Fe2O3、Cr2O3、Ni2O3）的含量增 多。 这些现象使 SURP 试样的具有较高的开路电位和自腐蚀电位、较大的阻抗曲 率半径和较低的自腐蚀电流密度，试样的抗腐蚀性能得以提升；因此，SURP 能 大大减少试样在多相流环境下 304 SS 界面损伤的失重量，延长材料的空蚀孕育 期和抑制增长期的腐蚀率；可见，SURP 304 SS 抗界面损伤性能提升的机理是相 变、硬度、残余应力、晶粒细化、表面电势、钝化膜的组成和厚度等共同作用的 结果。 其次，对 SURP 试样在不同的滚压工艺和选矿工艺参数下进行空蚀、冲蚀和 空蚀-冲蚀耦合试验，揭示了滚压工艺和选矿工艺参数在多相流环境下对 304 SS 试样界面损伤的影响。试验表明选矿工艺对 SURP 304 SS 的界面损伤行为具有 显著的影响 浆料浓度的增加会降低试样的抗冲蚀、 空蚀-冲蚀性能， 其表现在浆 料浓度增加时会增加试样表面的磨损损失，但抗电化学腐蚀性能略微增强；随浆 料 pH 的增加，试样的抗电化学腐蚀性能则先增强后减弱；冲蚀速度的增加将加 速冲蚀过程中的摩擦磨损从而降低试样的抗冲蚀性能； 低冲击角时冲蚀的界面损 伤以切削磨损为主， 高冲击角时冲蚀的界面损伤受变形磨损和电化学腐蚀共同控 制； 冲蚀过程中引入空蚀将大大增加试样的失重量，增加腐蚀介质中的气含量将 万方数据 II 降低设备的使用寿命；粒径的增加在提升抗电化学腐蚀性能的同时减小失重量， 试样的抗空蚀-冲蚀性能得以提升；空蚀-冲蚀耦合作用比二者单独作用更严重， 其不仅增加试验过程中的磨损腐蚀，也增加腐蚀中的电化学腐蚀速率。不同滚压 遍数下 304SS 界面损伤的表征和试验表明，SURP 510 遍时 304 SS 表面维氏硬 度和残余应力达到饱和， 晶粒细化速度达到最大化而缺陷生成速度处于较低水平， 同时晶间的表面电势差有最小值，奥氏体和马氏体之间的相变处于稳定状态。因 此，SURP 510 遍时 304 SS 有最佳的抗界面损伤性能，并且材料经 SURP 处理 后能大幅减少 304 SS 在多相流环境下的界面损伤。 最后，对多相流和 304 SS 的界面以分子动力学和流体力学的角度进行了微 观和宏观方面的跨尺度模拟， 进一步丰富了多相流环境下选矿设备材料的界面损 伤的行为和机理。结合能表明，在 Cl-环境下，Fe 和 Cr 金属单质的E（结合能 的绝对值）均大于其氧化物的E。钝化膜中 Fe 和 Cr 与 Cl-有较强的相互作用 力，吸附紧密，Fe2O3和 Cr2O3与 Cl-相互作用较弱；费米能级附近的能带和态密 度表明，O 2p、Cr 3d、2p 和 Fe 3d、2p 是影响钝化膜中腐蚀电流大小的因素。 Fe2O3和 Cr2O3中 O 元素和 Fe、Cr 元素的 s 轨道电子形成共价键不能自由运动， 产生电流的电子为受到较强的原子核束缚力电子和 d 轨道电子。 而 Fe 和 Cr 对应 的 s 轨道电子为可自由运动，易产生电流。在 SURP 试样表面钝化膜中高价态金 属氧化物和致密性氧化物的含量比基体材料的多，因此，SURP 试样具有良好的 抗腐蚀性能。结合能、能带和态密度表明 304 SS 试样钝化膜组成的改变是界面 损伤性能提升的机理之一。 冲蚀率是与冲蚀速度、 冲蚀角度和颗粒粒径密切相关， 宏观模拟获得的冲蚀速度、 冲击角度和颗粒粒径对冲蚀的影响与试验数据相吻合。 该论文有图 100 幅，表 30 个，参考文献 195 篇。 关键词关键词多相流；选矿设备材料；超声表面滚压；界面损伤；钝化膜 万方数据 III Abstract As a common occurrence in the field of mineral processing that interfacial damage behaviors and mechanisms of mineral processing equipment materials under multiphase flow environment, is one of the key reasons for the failure of mineral processing equipment materials. Every year, an enormous quantity of steel is corroded by cavitation and erosion, causing huge economic losses. In the wet mineral process, the addition of foaming agent makes ore pulp environment more complex, which deteriorates the damage of flow passage components caused by erosion and cavitation. Therefore, it is of great necessity to conduct surface modification of mineral processing equipment materials so as to endow them with excellent abrasive resistance as well as corrosion resistance. Meanwhile, research on interfacial damage behaviors and mechanisms between mineral processing equipment materials and multiphase flow should be conducted to reduce the damage rate of metal material interfacial and prolong the service life of key mineral processing equipment. In this paper, 304 austenitic stainless steel 304 SS, which is a common material of key overcurrent components in mineral processing equipment, is taken as the research object. First, surface modification of 304 SS was pered by surface ultrasonic rolling processing SURP; and the microstructure, mechanical properties, surface potential, passivation film state and electrochemical properties of matrix and SURP 304 SS were characterized subsequently. The results show that the SURP specimens display a better abrasive resistance due to the increase of Vickers hardness and residual stress on the surface of the specimens and the transation of some austenite phase into martensite phase. The increase of Vickers hardness and residual stress helps to reduce the scratch and indentation caused by the collision between specimens and medium flow; and the phase transition of austenite phase into martensite can absorb the impact energy and avoid the crack growth under the effect of cavitation. In addition, the surface of SURP 304SS specimens has the phenomenon of grain refinement, and the surface potential difference between grain boundaries decreases. At the same time, the proportion of O, Cr and Ni in the passivated film increases while the proportion of Fe decreases. The enrichment of Ni is more obvious. Furthermore, the content of high oxide CrO3, Ni2O3 and dense oxide Fe2O3, Cr2O3, Ni2O3 in the passivated film increases. These phenomena endow the SURP specimens with higher open circuit potential and corrosion potential, larger impedance curvature radius and lower corrosion current density. In other words, the corrosion resistance of the sample 万方数据 IV has been greatly improved. Accordingly, it can be summed up that SURP greatly reduces the mass loss of 304 SS interfacial damage of the specimens in the environment of multiphase flow, prolongs the cavitation incubation period of the material and inhibits the corrosion rate during the growth period. In a word, the mechanism of SURP 304 SS resistance to interfacial damage is the combined effects of phase transition, Vickers hardness, residual stress, grain refinement, surface potential, and the composition and thickness of passivation film. Secondly, cavitation, erosion and cavity-erosion coupling experiments were carried out on SURP samples with different SURP parameters and mineral processing parameters. And the effects of SURP parameters and mineral processing parameters on the interfacial damage of 304 SS specimens in multiphase flow environment were revealed. The experiments show that the mineral processing parameters have a significant effect on the interfacial damage behavior of SURP 304 SS The increase of Ore Pulp Mass reduces the erosion resistance, cavitation erosion and erosion perance of the specimens, for the surface abrasion loss of the specimens increases on the one hand while the electrochemical corrosion resistance is slightly enhanced on the other when the Ore Pulp Mass increases; with the pH of Ore Pulp increasing, the electrochemical corrosion resistance of the specimens increases at first then decreases; the enhancing of erosion speed would accelerate the friction and abrasion between particles and interface, so the erosion resistance of the specimens would reduce. The erosion interfacial damage is mainly caused by cutting wear at low impact angle while controlled by deation wear and electrochemical corrosion at high impact angle. The mass loss of the specimens witnesses a sharp increase when cavitation is added to erosion process, and the increase of gas content in the corrosive medium would reduce the service life of mineral processing equipment. Increasing of particle size, would reduce the mass loss while improving the electrochemical corrosion resistance. Thereby, the cavitation-erosion corrosion resistance of the specimens can be improved. The characterization and experiments of interfacial damage of 304SS under different SURP times show when the surface of 304 SS is processed with SURP for 5 10 times, the Vickers hardness and residual stress reach saturation, the grain refinement speed is maximized while the defect generation speed is at a low level; at the same time, the surface potential between the crystals has a minimum difference, and the phase transition between austenite and martensite is in a stable state. In short, 304 SS has the best perance of anti-interfacial damage when SURP 510 times, and SURP can 万方数据 V significantly reduce the interfacial damage of 304 SS in a multiphase flow environment. Finally, the interface between multiphase flow and 304 SS was simulated from the perspectives of molecular dynamics and fluid mechanics at the micro and macro scales respectively, which further enriches interfacial damage behaviors and mechanisms between mineral processing equipment materials and multiphase flow. The binding energy shows that, the E absolute value of binding energy of Fe and Cr metal elements is greater than that of oxides in the corrosive solution which contains Cl-. In the passivated film, Fe and Cr have a strong interaction force with Cl- and the adsorption is close while Fe2O3 and Cr2O3 are relatively weak in this aspect; The energy band and state density near the Fermi energy level indicate that O 2p, Cr 3d, 2p and Fe 3d, 2p are the factors affecting the corrosion current in the passivation film, where O and s orbital electrons of Fe and Cr elements covalent bonds, so the electrons that generate the current are the electrons bound by the stronger nucleus Nuclear binding force and d orbital electrons in Fe2O3 and Cr2O3. By contrast, the s orbital electrons of Fe and Cr are free to move, thus being more capable of generating current. The content of high oxide and dense oxide in the passivation film on the surface of SURP specimens is higher than that of the matrix material. Therefore, SURP specimens has a better corrosion resistance. The binding energy, energy band and state density indicate that the change of passivation film composition of 304 SS specimens is one of the mechanisms to improve the interfacial damage perance. Erosion rate is the function that is related to erosion speed, erosion Angle and particle size. The simulated calculation of erosion rate under erosion speed, erosion Angle and particle size is consistent with the rules in the experiment. The thesis contains 100 figures, 30 tables and 195 pieces of references. Keywords Multiphase Flow; Mineral Processing Equipment Materials; Ultrasonic Surface Rolling Processing; Interfacial Damage; Passivation Film 万方数据 VI 目目 录录 摘摘 要要 ........................................................................................................................... I 目目 录录 ........................................................................................................................ VI 图清单图清单 .......................................................................................................................... X 表清单表清单 .................................................................................................................... XVII 变量注释表变量注释表 ............................................................................................................. XIX 1 绪论绪论 ........................................................................................................................... 1 1.1 研究背景及意义..................................................................................................... 1 1.2 冲蚀与空蚀的防护................................................................................................. 1 1.3 表面自纳米化的发展........................................................................................... 11 1.4 多相流界面仿真模拟........................................................................................... 13 1.5 本文研究内容....................................................................................................... 16 1.6 本文技术路线....................................................................................................... 17 2 试验和方法试验和方法 ............................................................................................................. 19 2.1 试验原料............................................................................................................... 19 2.2 试验药剂与仪器................................................................................................... 20 2.3 试验方法与试样表征........................................................................................... 25 3 304 SS 的的 SURP 表面改性表面改性...................................................................................... 31 3.1 改性试样的微观形貌和力学性能....................................................................... 31 3.2 改性试样的表面钝化膜....................................................................................... 35 3.3 改性试样的静态电化学腐蚀性能....................................................................... 44 3.4 改性试样的性能评价........................................................................................... 45 3.5 SURP 提升 304 SS 表面性能的机理 ................................................................... 51 3.6 本章小结............................................................................................................... 53 4 SURP 试样抗空蚀性能研究试样抗空蚀性能研究 ................................................................................... 55 4.1 SURP 滚压遍数对试样抗空蚀性能的影响......................................................... 55 4.2 浆料浓度对 SURP 试样抗空蚀性能的影响....................................................... 68 4.3 矿浆 pH 值对 SURP 试样抗空蚀性能的影响 .................................................... 75 4.4 章节小结............................................................................................................... 79 5 SURP