【作者】 刘琼；

【导师】 杜忠泽； 王庆娟；

【作者基本信息】 西安建筑科技大学 ， 材料加工工程， 2009， 硕士

【摘要】 超细晶材料具有优良的物理性能和化学性能,是为适应社会发展和需求而逐步开发出来的一种新型材料。在制备超细晶材料的技术中,等径弯曲通道挤压技术(EqualChannel Angular Pressing,简称ECAP)被认为是目前最具工业化应用前景的技术之一。本文以工业纯铜T1为原料,采用两通道内交角φ为90°,外接弧角Ψ为20°的ECAP模具制备出晶粒大小为0.2～0.3μm的块体超细晶铜,利用E-t曲线、动电位极化曲线、电化学阻抗谱(EIS)等电化学方法和x-射线能谱仪、扫描电镜测试方法研究了ECAP超细晶铜和挤压前退火态粗晶铜在不同条件下的腐蚀行为,主要研究结果如下:(1)室温条件下,在0.5mol/L NaCl溶液中,ECAP超细晶铜与粗晶铜相比,前者腐蚀电流密度较低,腐蚀速率减小,从电化学分析和微观腐蚀形貌来看,随着浸泡时间的延长,超细晶铜的腐蚀表面较光滑,且较为均匀,而粗晶铜的局部腐蚀十分严重,超细晶铜表现出更好的耐蚀能。在氯化钠溶液中浸泡64h后,ECAP超细晶铜和粗晶铜的腐蚀电流密度均减小,腐蚀速率减慢,表面腐蚀产物保护作用增强。(2)在0.5mol/L NaCl溶液中,随着温度的升高,ECAP超细晶铜和粗晶铜表面膜的孔隙率增大,氯离子在膜中更容易扩散,从而使电极的腐蚀速率增大,耐蚀性能降低。当温度达到90℃时,粗晶铜比超细晶铜具有较大的腐蚀电流密度和较高的致钝电位,表明粗晶铜比超细晶铜更易腐蚀。(3)室温条件下,随着氯离子浓度升高,ECAP超细晶铜和粗晶铜的腐蚀电位均负移,腐蚀电流密度、致钝电流密度及维钝电流密度都增大,这表明这两者表面钝化膜在高浓度氯离子溶液中更易遭到破坏,耐蚀性能降低。当氯离子浓度达到1.5mol/L时,超细晶铜和粗晶铜具有相似的腐蚀和钝化过程,耐蚀性能相似。(4)室温条件下,在含有硫离子的0.5mol/L氯化钠溶液中,随着硫离子浓度的升高,ECAP超细晶铜和粗晶铜的腐蚀电位减小,腐蚀电流密度增大,钝化膜更易遭到破坏,使材料的耐蚀性能降低。在含有0.01mol/L硫离子的氯化钠溶液中,超细晶铜比粗晶铜腐蚀电流密度低且更早进入钝化,表现出更佳的耐蚀性。(5)室温条件下,在盐酸溶液中,ECAP超细晶铜的腐蚀电流密度略高于氢氧化钠溶液和氯化钠溶液中的腐蚀电流密度。在氢氧化钠溶液中,随着电极电位的升高,阳极极化进入过钝化区,超细晶铜表面以很大的阳极电流密度溶解,钝化膜在局部遭到破坏,腐蚀又重新加剧。更多还原

【Abstract】 Ultra-fine grained（UFG） material is a new type of material with excellent physical properties and chemical properties to meet the needs of social development.Equal Channel Angular Pressing（ECAP） is considered one of the most promising industrial technologies in all preparation technologies of UFG material.In this paper,UFG T1（0.2-0.3μm） was made by ECAP（Φ=90°,Ψ=20°）,and the corrosion behaviors of ultra-fine grained（UFG） Cu and annealed coarse-grained（CG） Cu were studied in differnet systems through E-t curve, potentiodynamic polarization curve,electrochemical impedance spectroscopy（EIS）,X-ray energy dispersion spectrometer and scanning electron microscopy.The main research results were as follows:（1） Under room temperature,in 0.5mol/L NaC1 solution,UFG Cu exhibited lower corrosion current density in comparison with CG counterpart.It was that with the extension of immersion time,the corrosion surface of UFG Cu was very smooth and more uniform,but the localized corrosion of CG Cu was very serious,which indicated that UFG Cu had a better corrosion resistance than CG Cu.Immersion 64h later,the corrosion current density of UFG Cu and CG Cu decreased,and the protective effect of corrosion products enhanced.（2） In 0.5mol/L NaC1 solution,with increasing temperature,the surface film porosity of UFG Cu and CG Cu increased,which made C^1- so easily spread in the passive film that their corrosion rate increased and the protective character against corrosion reduced.When the temperature reached 90℃,CG Cu exhibited higher corrosion current density and passivation current,which showed that CG Cu was more likely to suffer corrosion than UFG Cu.（3） Under room temperature,with increasing concentration of C^1-,the corrosion potential of UFG Cu and CG Cu decreased,meantime their corrosion current density, passivation current density and blunt-dimensional current all increased,which indicated that copper was more likely to suffer damage and its protective character against corrosion reduced.In 1.5mol/L C^1- solution,UFG Cu and CG Cu had corrosion and passivation process,which indicated that UFG Cu and CG Cu had similar corrosion resistance.（4） Under room temperature,in 0.5mol/L NaC1 solution with S^2-,with increasing concentrations of S^2-,the corrosion potential of UFG Cu and CG Cu decreased,and their corrosion current density increased,which indicated that copper’s passive film was more likely to suffer damage and its corrosion resisting property reduced.In NaC1 solution with 0.01mol/L S^2-,UFG Cu had lower corrosion current density,earlier occurred passivation and showed better corrosion resistance than CG Cu.（5） Under room temperature,in HC1 solution,the corrosion current density of UFG Cu was higher than in NaC1 solution and NaOH solution.In NaOH solution,with increasing electrode potential,anodic polarization entered transpassive region,the surface of UFG Cu dissoluted in a large current density,copper’s passive film suffered damage on the local scale, and corrosion increased again.更多还原