电流密度对镀锡板钝化膜厚度、成分及膜中铬元素的影响

镀锡板钝化过程中的电流密度对钝化膜的性能影响较大,同时膜的性能又与厚度、成分、Cr元素含量等因素相关。实验通过改变镀锡板钝化膜生成过程中的钝化电流密度,探究电流密度对生成的钝化膜的厚度和成分的影响,并使用X射线光电子能谱(XPS)对在此电流密度下得到的钝化膜中Cr元素的组元和价态进行分析。结果表明在电流密度由3A/dm~2变为0.5A/dm2时:钝化膜厚度变薄,钝化膜中Sn元素含量增加,Cr元素含量减小;钝化膜中Cr元素的组元均由单质Cr、Cr_2O_3、Cr(OH)_3构成且不发生变化,但各价态组分的相对含量发生改变,低价态Cr含量降低,高价态Cr含量升高;镀锡板钝化膜组成成分呈现层状分布。     

不锈钢表面钝化膜特性的研究进展

金属钝化膜的研究已从宏观研究进展到结构和组成等微观研究阶段.通过不锈钢表面自发形成的薄而稳定的钝化膜主要由金属氧化物组成.钝化膜的厚度由不锈钢的成分、溶液pH值、电位、电解液和温度等因素决定,一般不超过10 nm.综述了不锈钢表面钝化膜的厚度、组织和结构,钝化膜的形成和生长机理、半导体性能和耐蚀性,讨论了纳米结构对不锈钢钝化膜性能的影响.当前研究重点是开发高强度和耐磨性、更好耐蚀性的新型不锈钢,而采用纳米技术是有效途径之一.     

热镀锌表面铈盐钝化

采用Ce(NO3)3取代铬酸盐对热镀锌表面进行钝化，通过研究钝化液组成、pH值、温度及钝化时间等因素对钝化成膜及其耐蚀性的影响，获得钝化处理最佳技术条件（质量浓度）为：Ce(NO3)320g/L,H2O2(25-35)mL/L,HBO32g/L,pH(1.4-1.75)，温度45－50℃，时间40－90s。检测分析表明，采用该研究成果可获得效果与低铬酸盐钝化相近的耐蚀性较好的金黄色钝化膜。这对于改变钝化处理毒性容易造成环境污染的现状具有积极的现实意义。     

成膜时间对AZ31B镁合金Mn-Y转化膜的影响

镁合金表面稀土盐转化膜是近些年发展起来的一种绿色环保的表面处理技术,本文采用了电子扫描显微镜(SEM)、析氢实验、电化学工作站及X射线能量色散光谱(EDS)考察了不同成膜时间对获得的Mn-Y转化膜的微观形貌、耐蚀性、半导体特性及组成的影响。实验结果表明,随着成膜时间的增加,AZ31B镁合金表面逐渐生成一层转化膜,膜层呈泥巴状,当成膜时间为5 min时,基体表面的转化膜层最为密实。析氢实验结果显示,当成膜时间为5 min时,镁合金的析氢量最小,说明其耐蚀性最好;动电位极化曲线和电化学交流阻抗谱结果同样显示,随着成膜时间的增加,镁合金表面的耐蚀性不断增加,成膜时间为5 min的试样耐蚀性最好。Mott-Schottky曲线测试结果表明,镁合金表面膜层为n型半导体,5 min获得镁合金试样的施主浓度N_D最小,平带电位E_(fb)最正,耐蚀性能最好。EDS结果表明,化学转化膜的主要成分由锰、钇的磷酸盐和氧化物组成。     

高纯铁素体不锈钢在湿法磷酸中的耐蚀性及机理探讨

本文采用腐蚀实验、电化学测试及X光电子能谱(XPS)对不同成分的高纯铁素体不锈钢(F·S·S)在湿法磷酸中的耐蚀性及其耐蚀机理进行了研究。结果表明,铬是控制F·S·S耐蚀性的主要元素,随钢中铬量增加,耐蚀性提高。当Cr=25％时,F·S·S的耐蚀性显著增加,出现了突变效应。钼的作用则与钢中铬含量有关,足够量的铬存在对改善F·S·S耐蚀性是必不可少的。 良好耐蚀性的F·S·S表面钝化膜内存在明显的铬富集区,但没有发现钼的富集。F·S·S的耐蚀性取决于膜内Cr(Ⅰ)的相对富集程度。钼改善F·S·S耐蚀性是通过富集于活性表面上的钼氧化物大大降低了钢的活性溶解速度,促使均匀膜快速形成;同时提高了膜内铬的富集程度,进一步加强了铬的有效作用。     

超声辅助镁合金表面碳酸盐复合膜耐蚀性研究

将超声波用于镁合金表面(Mg_6Al_2(OH)_(16)CO_3?4H_2O)/MnCO_3复合膜的制备,通过扫描电镜(SEM)、X射线衍射(XRD)和能谱(EDS)分析了膜层的表面形貌和成分,利用极化曲线和交流阻抗(EIS)评价了该转化膜的耐蚀性,研究了超声时间对膜层结构及耐蚀性的影响规律。研究结果表明:超声辅助能够促进膜层的形成,但过长的处理时间会导致膜层质量的恶化,当时间为3 h时,膜层较厚且完整,耐蚀性明显优于锾合金基体,腐蚀电流密度约为钱合金基体的1/10。     

镀锡板表面特性对涂饰性的影响研究

镀锡板在食品包装领域有着广泛的应用。本文采用电子扫描电镜、电化学分析和划痕分析方法,研究了镀锡表面性能对涂饰性的影响。结果表明,镀锡板表面钝化膜含铬量对涂饰性有着重要的影响。当钝化膜含铬量控制10～20 mg／m2范围内,镀锡板表面具有较好的涂饰性。烘烤温度和烘烤时间对镀锡板表面形貌和耐蚀性无明显影响,但对涂饰性有着明显影响。烘烤时间为15 min ,烘烤温度在200℃左右,镀锡板表面与漆膜具有较好的结合力。     

钝化膜对镀锡板漆膜结合力的影响

通过化学溶解+ICP法、X射线光电子能谱分析法研究了钝化膜的组成及结构,确认铬酸盐钝化膜中含有Cr_2O_3、Cr(OH)_3、Cr和Cr(Ⅵ),不同镀锡板钝化膜的差异主要在总Cr量以及各组分之间的比例,这种差异对常规附着力测试无影响,但在电解脱膜测试时有明显差异。分析认为镀锡板与漆膜的结合存在机械附着和化学附着,在涂料流动性及固化条件良好的情况下,机械附着足以保证漆膜结合力,钝化膜影响不大;当漆膜有破损时且有水或液体存在时则需要依靠钝化膜来保证漆膜结合力。     

锌表面稀土化学钝化及耐蚀性研究

采用三价铈盐对锌进行化学钝化处理 ,研究了有关工艺参数对锌表面稀土转化膜耐蚀性的影响 ,测量了钝化过程中试样的交流阻抗谱 (EIS)和表面显微硬度的变化 ,探讨了稀土转化膜的形成机理 ,并对成膜动力学进行了分析。随着钝化液的铈盐浓度、pH值、温度和处理时间的增加 ,稀土转化膜的耐蚀性也相应提高 ,一定条件下可达到或优于铬酸盐钝化的防蚀性能。稀土钝化成膜反应动力学符合Arrhenius方程 ,反应活化能约为 6 4 8kJ/mol。     

醇盐体系增材制造钛合金的电化学抛光机理

电化学抛光是增材制造TC4钛合金表面处理的方法之一.采用循环伏安、交流阻抗、计时电流及X射线光电子能谱仪(XPS)等测试方法,研究了乙二醇-氯化钠电解液中增材制造TC4钛合金的电化学抛光行为.结果表明,钛合金在乙二醇-氯化钠体系中的氧化过程是Ti→TiO→Ti₂O₃→TiO₂.施加不同的电位,影响钛合金表面氧化膜(也可称为钝化膜)厚度的演化,随着施加电位的增大,氧化膜厚度先增大后减小.根据氧化膜厚度的变化规律提出两步抛光法,与单一钝化区电位抛光相比,两步抛光法抛光速率更大.在25 min时钛合金表面取得了最佳抛光效果,此时粗糙度为2.6μm.     

镁合金电镀铝前处理工艺的探讨

采用氢氟酸对AZ31镁合金电镀铝进行前处理,并对钝化处理得到的转化膜的物相、表面形貌和耐蚀性进行测定.结果表明,钝化处理得到的转化膜对镁合金基体有较好的保护作用,符合镀前处理的要求.     

Corrosion resistance and ion dissolution of titanium with different surface microroughness

In vitro corrosion resistance and ion dissolution of commercial pure titanium with different surface microroughness are studied adopting constant potential meter and atomic absorption spectroscopy. In terms of the surface roughness, titanium samples are divided into 5 groups: smooth surface, machining surface, 2 different microroughness surfaces and macrorough surface. Each group contains three category samples under different treatments: natural oxidation (24 h exposure to air), oxidation under 400 degrees C (400 degrees C, 45 min thermal oxidation), oxidation under 700 degrees C (700 degrees C, 45 min thermal oxidation). In Hanks corrosion media, comparative studies through constant potential anode polarization curves and titanium release rates of the 5 groups of Ti samples demonstrates that oxidation under 400 degrees C best increase corrosion resistance and decrease ion release sharply, oxidation under 700 degrees C is better than natural oxidation. Ti samples with a different surface roughness all have good corrosion resistance and their corrosion resistance drop with the raising of surface roughness. Comparing with macrorough surface and machining surface, microrough surfaces have better corrosion resistance and a lower ion release rate which are similar to those of smooth surfaces. Moreover, the corrosion resistance of machining surface Ti is the lowest. It is hypothesized that surface treatment methods such as surface thermal oxidation, surface aging and so on will improve the corrosion resistance and decrease the ion release rate of rough surface effectively by increasing the thickness of surface protection film, improving its structural uniformity and facilitating the formation of ordered, compact surface protection film.     

彩涂板脱漆缺陷对耐蚀性能影响分析

针对彩涂板压型后在使用过程中因表面漆膜脱落．造成耐蚀性能劣化的问题进行了分析,采用扫描电镜、能谱仪和盐雾腐蚀试验等方法,对缺陷板进行检验。结果表明,彩涂板前处理钝化层缺失是其产生脱漆缺陷、造成耐蚀性能下降的主要原因,而涂层厚度减薄也是其中原因之一。     

无铬钝化热镀锌耐指纹板的开发

针对首钢冷轧薄板公司冷轧的0.3~2.5 mm无铬钝化耐指纹DX15D+Z普通低碳钢薄板生产过程出现的耐指纹膜厚度不均,辊印敏感形成印痕等质量问题,提出化学涂机逆涂报停、耐指纹膜厚控制、钝化辊印等工艺控制措施。生产结果表明,薄板成品96 h盐雾耐蚀性,表面电阻试验,烤漆附着力等性能均满足要求。     

Microstructure Characteristic and Electrochemical Corrosion Behavior of Surface Nano-crystallization Modified Carbon Steel

The surface nano-crystallization( SNC) of carbon steel was achieved via a high-speed rotating wire-brushing process.Microstructure characteristics of SNC steel were systematically studied.The SNC steel surface exhibited marked deformed plastic flows and high surface roughness.Due to the accumulated strains,a deformed gradient layer with thickness of 40-50 μm was produced,and the grain size of the topmost zone was about 50-100 nm.X-ray photoelectron spectroscopy( XPS) analysis indicated that enhanced Fe oxides and Cr oxides were generated.Electrochemical corrosion tests,including open circuit potential( OCP),electrochemical impendence spectroscopy( EIS),potentiodynamic polarization( PDP) and potentiostatic polarization( PP) were conducted to study the corrosion behavior of SNC steel in 3.5 mass% Na Cl solution,where an improved corrosion resistance was observed.The resulted improvement resulted from the dominated positive effects( the attached Cr alloying element and enhanced oxide film) against the negative effects( the higher roughness and the improved corrosion activity of surface microstructure).     

氧化膜对14Cr12Ni2WMoVNb钢QPQ渗层的室温摩擦磨损和腐蚀性能的影响

为了研究14Cr12Ni2WMoVNb钢QPQ(淬火-抛光-淬火)处理后的氧化膜对渗层室温摩擦磨损和腐蚀性能的影响,利用金相、X射线衍射分析、扫描电镜、能谱分析、划痕仪、摩擦磨损试验机和电化学工作站对试样进行了表征.结果表明:氧化膜对渗层室温摩擦学性能的影响与载荷大小有关.在摩擦时间均为4 min情况下,载荷较小(50 N)时,氧化膜可以降低摩擦系数和体积磨损率;载荷较大(100 N)时,氧化膜被破坏无法降低体积磨损率.氧化膜可明显提高渗层的耐腐蚀性能.含氧化膜试样的极化曲线有明显的钝化区,点蚀电位为-13 mV,去除氧化膜试样在盐雾腐蚀12 h后表面有大范围的腐蚀区域,而含氧化膜试样盐雾腐蚀48 h后才有大区域腐蚀发生.      

Electron microscopy study of the passivating layer on iron-nickel martensite

A passivating oxide layer is known to form rapidly on the surface of Fe or Fe alloys exposed to air at low temperature. The properties of this passivating layer largely control the low temperature oxidation and corrosion properties of iron. It is hence important that the nature of this passivating layer be well understood. The work reported here principally involved a transmission electron microscopy examination of the thin oxide film formed on the surface of Fe?12Ni alloys on exposure to air at room temperature. Using high resolution microscopy the oxide particles of the film could be directly resolved and their structure and morphology characterized. The following conclusions were drawn from these characterization studies: 1) a passivating oxide layer (principally Fe₃O₄) forms spontaneously on the surface of Fe?Ni alloys on exposure to air at room temperature; 2) the orientation relation between the oxide and the metal surface depends on surface orientation; the Bain relation is obeyed when the alloy surface is (100)_α while the Nishiyama-Wasserman relation is obeyed on other low index surfaces. This phenomenon is attributable to the need to accommodate the misfit strain between the oxide and the substrate; 3) the oxide layer consists of dispersed, small (～20Å) oriented particles rather than a continuous thin film; and 4) the size of the oxide particles and the density of their distribution is related to the crystal surface orientation and condition.     

镀锌层表面新型环保钝化膜的耐腐蚀性能

 通过扫描电镜、辉光光谱、电化学测试、盐雾实验及湿热实验等手段探讨了用于钢板镀锌层表面A、B两种新型环保钝化膜的微观状态和耐腐蚀性能。结果表明：A型环保钝化膜的耐腐蚀性能明显优于传统铬酸盐钝化膜;B型环保钝化膜的耐腐蚀性能略低于传统铬酸盐钝化膜;并讨论了A型环保钝化膜耐腐蚀性能优异的原因。     

Effect of pH on Semiconducting Property of Passive Film Formed on Ultra-High-Strength Corrosion-Resistant Steel in Sulfuric Acid Solution

Because Cr9Ni5MoCo14 is a new ultra-high-strength corrosion-resistant steel, it is important to study its corrosion behavior in sulfuric acid solution, which is used to simulate the aggressive environment. The effect of pH on the electrochemical and semiconducting properties of passive films formed on ultra-high-strength corrosion-resistant steel in sulfuric acid solution was investigated by means of the potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and X-ray photoelectron spectroscopy (XPS). The results indicated that Cr9Ni5MoCo14 steel showed a passive state in acid solutions. The corrosion behavior of this Cr9Ni5MoCo14 alloy was influenced by the passive film formed on the surface, including thickness, stability, and partitioning of elements of the passive film. The passive current density decreases with increasing pH, and the corrosion resistance was enhanced by the increasing thickness and depletion of the defects within the passive film. Moreover, an enrichment of chromium (primarily the oxides of Cr) and depletion of iron in the passive film led to improved corrosion resistance. These results can provide a theoretical basis for use of this alloy and further development of ultra-high-strength corrosion-resistant steel in today’s society.     

Effect of Pulsed Plasma Treatment on Structure and Corrosion Behavior of Sm-Co and Nd-Fe-B Magnets

The combination of conventional ion-plasma deposition and pulsed plasma technologies (PPT) has been applied for rare-earth Sm-Co and Nd-Fe-B based magnets, to provide them with enhanced corrosion resistance. The influence of pulsed plasma treatment on Sm-Co magnets with deposited titanium coatings has been investigated. It was revealed that the thickness of modified layer significantly depends on the thickness of initial titanium film and plasma treatment regimes. As a result of plasma treatment with energy density of 30 J/cm^b for 5 pulses fine-grained layer with me thickness of 70 microns has been formed on the Sm-Co magnet with pure titanium film of 50 μm. According to SEM analyses considerable diffusion of titanium to the bulk of the magnet on the depth of 20 microns took place. Such reaction enhances strong bonding between the coating and the magnet. The effects of plasma processing on corrosion properties of Nd-Fe-B sintered magnets with ferroboron Fe₈₀B₂₀ (wt.%) coatings have been studied. The tests were carried out in naturally aerated sodium sulphate solutions by polarization method. It was shown that polishing of the initial surface before plasma treatment and ferroboron deposition have a strong influence on the corrosion behavior of Nd-Fe-B magnets.