摘要
针对材料类学生教学需求,以科研项目为牵引,设计了稀土合金化增强耐候钢表面锈层保护性能的实验教学案例。该实验案例以海洋大气环境下耐候钢耐蚀性能亟待提高这一实际工程问题为切入点,通过现场大气曝露腐蚀实验、实验室模拟加速腐蚀实验来评价耐候钢的耐腐蚀能力。通过扫描电镜、X射线衍射分析等物理方法和极化曲线等电化学方法,研究分析了稀土耐候钢在近海大气环境下表面锈层的形貌、物相组成、合金元素分布及其电化学腐蚀行为。利用综合实验结果分析了特定腐蚀环境下稀土耐候钢的耐蚀性能和耐蚀机理。该实验教学案例以“问题提出-材料制备-腐蚀行为分析-耐蚀性能评价”为主线,综合性强,涉及材料合金成分设计、电化学腐蚀机理、表征技术、电化学分析等众多知识点,在一定程度上实现了专业知识的系统化和一体化,对学生创新意识和研究能力的培养具有很好的推动作用。
[Objective]In response to the teaching needs of students in the field of materials,an experimental teaching case of“enhancing the protective performance of the rust layer on weathering steels(WSs)through rare-earth(RE)alloying”was designed.The experiment aimed to improve the corrosion resistance of WSs in a marine atmospheric environment.The complete experimental process can strengthen students’research abilities and innovative thinking.[Methods]In this experiment,the corrosion resistance and mechanisms of RE WSs were studied using electrochemical and physical methods.Rusty WS samples were obtained through atmospheric exposure corrosion and laboratory accelerated corrosion simulation tests.Atmospheric corrosion tests were performed in Qingdao,a tropical coastal zone with high humidity,high Cl−1 concentration,and low industrial pollution.The accelerated corrosion test was performed using an LRHS-270-RY salt spray corrosion test chamber.The size of specimens was 50 mm×50 mm×3 mm.One test cycle was 60 min,i.e.,a 15 min spray stage and a 45 min drying stage,and the corrosion test times were 24,48,96,144,and 192 h.The phase composition of the corrosion products generated on all samples was characterized by X-ray diffraction(D/Max2500PC),and the surface morphology of the corrosion products was observed by scanning electron microscopy(Apreo S HiVac)equipped with an energy dispersive spectrometer.The electrochemical corrosion behavior of the RE WSs was studied and analyzed using a PARSTAT2273 electrochemical workstation using a conventional three-electrode system,with the WS samples as the working electrode,the saturated calomel electrode as the reference electrode,and the counter electrode as the platinum plate.The rusty samples of 10 mm×10 mm×2 mm were subjected to encapsulation treatment with acrylic resin to leave a working surface with an area of 1 cm^(2).The test solution was 3.5wt.%NaCl.[Results]The experimental results show that in a corrosive medium containing Cl−,significant pitting corrosion occurs on the surface of WSs during the initial stage of corrosion.The pitting pits on the surface of RE WSs are small,regular,and uniformly distributed,which is beneficial for inducing uniform corrosion on the steel surface and forming a dense rust layer in the later stage of corrosion.The RE elements in steels promote the generation of stable rust products such asα-FeOOH and the enrichment of copper in the rust layer.The addition of REs increases the corrosion potential and anodic polarization effect of the rusty WS samples during the electrochemical corrosion process.[Conclusions]REs can promote the formation of a dense,uniform,and stable rust layer on the surface of WS and improve its corrosion resistance.This experimental teaching case focuses on“Problem posing–Material preparation–Corrosion behavior analysis–Corrosion resistance evaluation,”covering multiple knowledge points such as alloy composition design,electrochemical corrosion mechanism,characterization technology,and electrochemical analysis.The experiment is conducive to the systematization and integration of professional knowledge and has a positive promoting effect on cultivating students'innovative awareness and research ability.
作者
岳丽杰
杨克森
韩金生
谢鲲
YUE Lijie;YANG Kesen;HAN Jinsheng;XIE Kun(College of Material Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,China;College of Civil Engineering and Architecture,Shandong University of Science and Technology,Qingdao 266590,China)
出处
《实验技术与管理》
CAS
北大核心
2024年第4期155-162,共8页
Experimental Technology and Management
基金
山东省优质专业学位教学案例库建设项目(鲁教研[2022]17号)
山东省优质专业学位教学案例库建设项目(鲁教研[2022]17号)
山东科技大学金属材料工程专业核心课程教学团队项目(JXTD20190507)。
关键词
耐候钢
耐蚀性能
表面锈层
教学案例
实验设计
weathering steel
corrosion resistance
surface rust layer
teaching case
experiment design
