【作者】 王云龙；

【导师】 姜兆华；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2010， 博士

【摘要】 为提高钢铁材料的耐磨耐蚀性能,本文运用等离子体液相电解沉积（PED）方法在不同钢铁表面生长陶瓷膜。利用阴极PED法采用硝酸-铝乙醇溶液（乙醇体系）在Q235碳钢和30CrMnSi合金钢表面制备陶瓷膜;利用阳极PED法分别在铝酸钠-磷酸盐（铝酸盐体系）和硅酸钠-次磷酸盐（硅酸盐体系）两种水溶液体系中制备陶瓷膜。采用SEM、XRD、EDS、FTIR、XPS等手段系统地研究了陶瓷膜层的微观组织结构,并分析了PED过程中膜层的形成过程,建立膜层微区放电模型。利用球-盘摩擦磨损试验、电化学测试技术、显微硬度测试、拉伸和热震实验研究了陶瓷膜层的耐磨性能、耐腐蚀性能、硬度和结合强度。研究表明,Q235碳钢、30CrMnSi合金钢两种基体在乙醇体系中获得的阴极PED膜层组成和结构相似,均由α-Al₂O₃和γ-Al₂O₃组成,其中α-Al₂O₃为主晶相。提高占空比或电流密度有利于α-Al₂O₃含量的提高,膜层的组成元素主要来自基体,基体中的主要元素铁只有少量存在于膜层和基体的界面处,膜层生长过程中沿基体表面向外生长。Q235碳钢在在铝酸盐体系中形成的陶瓷膜层由Fe₃O₄-FeAl₂O₄晶相组成,随峰值电流密度、频率的提高以及反应时间的延长,膜层的结晶度略有提高,在硅酸盐体系中形成的膜层主要含有O、Si和Fe元素。30CrMnSi合金钢表面阳极PED膜层Q235碳钢相似,在铝酸盐体系中制备的膜层为Fe₃O₄-FeAl₂O₄晶相,在硅酸盐体系中制备的膜层由O、Si和Fe元素元素组成。钢铁阳极PED膜层的组成元素来自基体和电解液,膜层沿基体同时向内向外生长。Q235碳钢在乙醇体系中的膜层的腐蚀电流密度为7.359×10-8A/cm2,腐蚀电位为-0.490V,其腐蚀电流比基体降低三个数量级。在铝酸盐体系和硅酸盐体系中获得的膜层的腐蚀电流密度分别为3.117×10?7A/cm2 ,和7.636×10?7A/cm2,腐蚀电位分别位0.423V,-0.491V。腐蚀电流均比基体降低2个数量级。Q235碳钢表面膜层的摩擦系数以铝酸盐体系膜层最低,乙醇溶液中的膜层次之。三种膜层的最高硬度分别为为1896Hv,1201Hv,987Hv,最大结合强度为17.8MPa,21MPa,和15MPa。总体而言,Q235碳钢在铝酸盐体系的膜层具有最低的摩擦系数和较好的耐蚀性能,乙醇体系膜层具有最好的耐蚀性能和较低的摩擦系数。30CrMnSi在乙醇体系中的膜层的腐蚀电流密度也比基体降低三个数量级,铝酸盐体系和硅酸盐中获得膜层腐蚀电流密度比基体降低100倍左右。30CrMnSi表面膜层硬度以及结合强度与Q235碳钢表面膜层相似。30CrMnSi在乙醇体系的膜层具有较好的耐磨、耐蚀综合性能。更多还原

【Abstract】 In order to improve the wear resistance and corrosion of steels, ceramic coatings were prepared on different kinds of steels by the technique of plasma electrolytic deposition （PED）. The cathodic PED method was employed to prepare ceramic coatings on Q235 carbon steel and 30CrMnSi alloy steel in Al（NO₃）₃-ethanol solution（ethanol system）. The anodic PED method was performed in NaAlO₂-NaH₂PO₄ solution （aluminate system） and Na₂SiO₃-NaH₂PO₂ solution （silicate system）, respectively, to prepare ceramic coatings on the steels. The microstructure of the coatings was systematically observed by SEM、XRD、EDS、FTIR and XPS,and the formation process of the ceramic coatings was also analyzed and the discharge model of the coatings was put up. The wear resistance, corrosion resistance, hardness and bonding strength of the ceramic coatings were studied by ball-on-disk tester friction and wear test, electrochemical test and in micro-hardness instrument , pull-off test and thermal shock method, respectively.The results show that the composition and structure of the coatings prepared in ethanol system on both Q235 carbon and 30CrMnSi alloy steels were similar. The coatings obtained were composed ofα-Al₂O₃ andγ-Al₂O₃, andα-Al₂O₃ was the dominated phase. Increasing the duty ration and current densities will be helpful for increasing the contents ofα-Al₂O₃ in the coating. The coating mainly consisted of Al and O elements. Only a little Fe, which was the main elements of in the substrates, was found in the interface of the substrates and the coatings. The coating only grew outward the surface of the substrate during its growth process. The coatings forming in aluminate system by anodic PED on Q235 and 30CrMnSi are composed of crystal phase of Fe3O4-FeAl2O4, the crystallinity of which was enhanced by increasing the current densities or the frequencies or prolonging the treating time, while coatings forming in silicate system were proved to be composed of non-crystal SiO₂. The anodic PED coating forming on Q235 were mainly composed of Al, O, Fe, and a little P elements and coating on 30CrMnSi were mainly composed of Si, O, Fe and a little Mn、Cr and P elements. The elements in both Q235 and 30CrMnSi made contribution to composition of the coating during anodic PED. The coating grew both inwards and outwards the substrates.The coatings forming on Q235 obtained in ethanol system showed a low current density of 7.359×10^-8A/cm² and corrosion potential of -0.490V, the corrosion current density of which was decreased by 3 order of magnitudes compared to the substrate. Coatings forming on Q235 in aluminate system and silicate system showed corrosion current densities of 3.117×10^-7A/cm², 7.636×10^-7A/cm², respectively, and corrosion potential of -0.423V, -0.491V, respectively. The corrosion current densities of the coatings were decreased by 2 order magnitudes compared to the substrates. Coatings forming on Q235 in aluminate system showed the lowest friction coefficient of all the coatings on its surface, and coatings obtained in ethanol system ranked second. Coatings obtained from the above three systems exhibited highest hardness of 1896Hv,1201Hv, 987Hv, respectively, and highest bond strength of 7.8MPa, 21MPa, 15MPa respectively. In a word, coatings obtained in aluminate exhibited the best corrosion resistance and lower friction coefficient; coatings obtained in ethanol system exhibited the lowest friction coefficient and better corrosion resistance.The corrosion current density of coating forming on 30CrMnSi in ethanol system was also decreased by three order of magnitudes compared to 30CrMnSi substrate. The corrosion current densities of coating obtained in aluminate and silicate system were nearly decreased by 100 times than that of the substrate. Coatings on 30CrMnSi alloy steel in all electrolytes showed similar hardness and bond strength of coatings on Q235 carbon steel. The coatings obtained in ethanol system exhibited the comprehensive performance of corrosion resistance and wear resistance更多还原