高熵合金涂层的微结构与耐腐蚀性能研究

发布时间：2018-06-20 02:39

本文选题：高熵合金涂层 + 磁控溅射　；参考：《四川理工学院》2015年硕士论文

【摘要】：材料表面合金化是金属表面防腐的重要手段之一,随着材料应用的多样化和使用环境的复杂化,对表面合金防腐层的性能要求也多重化。多数表面合金层难以同时满足高硬度、高耐热性、高耐腐蚀性、高耐磨抗性、抗氧化性等多重化性能的要求。高熵合金由五种及以上元素组成,各元素百分含量介于5at% 35at%,是一种新型合金体系。在高混合熵下,高熵合金表现出优异的综合性能,其中耐蚀性能甚至优于304不锈钢。将高熵合金引入到材料表面改性具有广泛的应用前景。本文采用等离子体五靶磁控溅射方法在X80基体上制得Al Ti Cr Ni Ta高熵合金耐蚀涂层。利用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)、能谱仪(EDX)、附着力划痕试验仪对涂层物相、微观形貌、成分、附着力进行表征。研究了溅射偏压(0V,-100V,-120V,-160V)和溅射气压(0.2Pa,0.4Pa,0.6Pa,0.8Pa)对沉积速率、表面粗糙度、膜密度、涂层附着力的影响。利用电化学方法对不同工艺下(溅射偏压、溅射气压、溅射功率、退火温度)Al Ti Cr Ni Ta高熵合金涂层在0.5mol/L H2SO4溶液中的耐蚀性能进行评价。并对涂层、X80基体在3.5wt%Na Cl溶液和0.5mol/L H2SO4溶液两种腐蚀体系中的腐蚀行为进行对比分析。研究发现:在溅射气压0.4Pa,负偏压为-100V下制得的Al Ti Cr Ni Ta高熵合金涂层,仅为单一的BCC结构,具有超细纳米晶结构,此时涂层最致密,粗糙度最小,临界载荷最大;电化学测试表明Al Ti Cr Ni Ta高熵合金可提高X80基体的耐Cl—腐蚀性能、致钝化性能,在0.4Pa,负偏压为-100V,0.5mol/L H2SO4溶液中涂层致钝电流密度最大;自然腐蚀状态下,Clˉ存在涂层腐蚀程度加剧;退火处理可释放部分涂层内应力,提高涂层耐局部腐蚀性能。
[Abstract]:Surface alloying is one of the most important methods for anticorrosion of metal surface. With the diversification of material application and the complication of application environment, the performance requirements of surface alloy anticorrosive coating are also multiple. It is difficult for most surface alloy layers to meet the requirements of high hardness, high heat resistance, high corrosion resistance, high wear resistance, oxidation resistance and so on. The high entropy alloy is composed of five or more elements. The content of each element is between 5at% and 35ats. it is a new alloy system. The high entropy alloy exhibits excellent comprehensive properties under high mixing entropy, and the corrosion resistance of the alloy is even better than that of 304 stainless steel. The introduction of high entropy alloy to the surface modification of materials has a wide application prospect. In this paper, Al Ti Cr Ni Ta high entropy alloy corrosion resistant coatings were prepared by plasma five target magnetron sputtering on X80 substrate. The phase, microstructure, composition and adhesion of the coating were characterized by X-ray diffractometer, field emission scanning electron microscope (SEM), atomic force microscope (AFM), energy spectrometer (EDS) and scratch test. The effects of sputtering bias voltage (0V / 100V) and sputtering pressure on deposition rate, surface roughness, film density and coating adhesion were investigated. The corrosion resistance of Al Ti Cr Ni Ta high entropy alloy coating in 0.5 mol / L H _ 2SO _ 4 solution was evaluated by electrochemical method (sputtering bias voltage, sputtering pressure, sputtering power, annealing temperature and annealing temperature). The corrosion behavior of the coating X80 substrate in 3.5 wtNaCl solution and 0.5 mol / L H2SO4 solution was compared and analyzed. It is found that the Al Ti Cr Ni Ta high entropy alloy coating prepared at the sputtering pressure of 0.4 Pa and negative bias voltage of -100 V is a single BCC structure with ultrafine nanocrystalline structure. The coating is the densest, the least roughness and the most critical load. The electrochemical measurements showed that the high entropy Al Ti Cr Ni Ta alloy could improve the Cl-corrosion resistance and passivation performance of the X80 matrix. In 0.4 Pa, the negative bias voltage was -100 V + 0.5 mol / L H _ 2SO _ 4 solution, and the coating had the highest passivation current density in 0.5 mol / L H _ 2SO _ 4 solution. The corrosion degree of the coating is aggravated under natural corrosion condition, and annealing treatment can release part of the internal stress of the coating and improve the local corrosion resistance of the coating.
【学位授予单位】：四川理工学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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