基板组织对镀锡板锡铁合金层及其耐蚀性的影响

研究了基板金相组织对镀锡板锡铁合金层及其耐蚀性的影响。结果表明,晶界较少的镀锡基板提高了电镀过程锡的形核率,促进了晶粒细小、孔隙较少锡铁合金层的生成。BA材自腐蚀电流明显小于CA材,BA材、CA材和DR材的自腐蚀电位差别较小。3种镀锡板循环伏安曲线均出现析氧峰,BA材氧化峰电流密度最高。     

镀锡板表面白线缺陷分析及改善

镀锡板是制作食品及饮料包装盒的重要原材料,现代工业化生产的电镀锡板是以冷轧优质低碳钢作基板,采用电镀的方法在钢板的两面均匀地镀上较薄的锡层,镀锡层经过软熔后形成锡所特有的光滑表面[1],从而钢的强度和成形性与锡的耐蚀性、锡焊性和美观外表完美的结合在一起.由于镀锡板主要用于各种食品及饮料等的外包装盒,镀锡板表面有划伤、白...     

低锡量镀锡板点锈原因分析和预防

针对低锡量镀锡板点锈问题,测试了锡层孔隙率、锡层在基板上的截面分布、基板表面轮廓形貌以及Tafel曲线,从电化学腐蚀角度分析了点锈的原因。结果表明：点锈产生的原因与镀锡板表面漏铁有关,Fe²⁺的溢出与锡层产生电势差,为原电池的形成创造了条件。助熔剂对镀锡板的腐蚀性和溜平作用使锡层聚集在基板表面的凹坑处,加剧了镀锡板表面漏铁的概率。基板的表面轮廓越复杂,凸点数越多,越易导致锡层分布越不均匀,镀锡板耐蚀性越差。为此,对助熔剂进行了管控,高锡量镀锡板仍用助熔剂助熔,低锡量镀锡板改为水助熔,且当助熔剂槽切换为水助熔的时候,需要确保槽内无助熔剂残留。对平整工艺段的基板表面轮廓进行管控,通过改变工作辊的毛化参数,降低连退基板的凸点数,同时限定凸点数低于80个/8 mm的基板可用于低锡量镀锡板的生产,如凸点数高于80个/8 mm,则用于高锡量镀锡板的生产实践。     

基板金相结构对镀锡板锡层特性及其结合力的影响

采用金相显微镜、扫描电镜和电化学分析方法,研究了基板金相结构对镀锡板锡铁层特性和锡层结合力的影响.结果表明,晶粒细小的镀锡基板获取的镀锡层较为粗糙,且镀锡层存在明显的孔隙;随着镀锡基板晶粒的增大,镀锡层的孔隙减少,且镀层均匀致密;晶粒粗大的镀锡基板沉积锡层的自腐蚀电位明显大于晶粒细小的镀锡基板表面镀锡层;晶粒粗大的镀锡基板表面沉积锡层的结合力较好.     

原板内应力对镀锡板耐蚀性的影响

通过测试原板的内应力及原板经过相同生产工艺得到的镀锡板的ATC值,研究了原板内应力对镀锡板耐蚀性的影响,并研究了影响机理。研究结果表明：原板轧制方向与垂直轧制方向内应力之差|X-Y|对镀锡板的耐蚀性影响显著,耐蚀性随|X-Y|的上升而上升。研究结果还表明,原板的|X-Y|对镀锡板耐蚀性的影响源于|X-Y|对原板酸洗后表面状态的影响,进而影响锡铁合金层结构,而镀锡板的耐蚀性多取决于合金层的结构。     

镀锡板冲压黑线缺陷的成因分析与改进

利用扫描电子显微镜、能谱仪、电化学工作站分析了化工喷雾罐顶盖冲压黑线及镀锡基板的缺陷形貌。结果表明,喷雾罐顶盖黑线处已裸露铁基体,且部分部位被氧化,镀锡板针状黑点或短线状黑点处的锡层已被破坏和氧化。利用电化学法脱去锡层,观察基板形貌,发现针状黑点对应的基板部位存在缺陷,而短线状黑点对应的基板部位未见异常。可以推断冲压黑线是由于镀锡板锡层因基板缺陷或擦伤而遭到破坏,经冲压变形后加剧铁基体裸露在外的程度导致形成黑色短线。为此,提出了相应的改进措施,避免了缺陷的产生。     

软熔条件对镀锡板合金层组织及其耐蚀性的影响

镀锡板合金层的耐蚀性好坏直接关系到镀锡板用作食品包装材料时的寿命。为此 ,研究了软熔过程中的时间与温度对镀锡板合金层形貌及其耐蚀性的影响。结果表明 ,随着软熔时间的延长和软熔温度的升高 ,镀锡板合金层的晶粒度增大 ,镀锡板的耐蚀性增强。     

镀锡板表面黑灰缺陷成因分析及对涂饰性的影响

电镀锡板在生产和存储过程中表面易产生黑灰缺陷,其对镀锡板的涂饰性、耐蚀性、美观性等均造成不利的影响。分析了电镀锡工艺、镀液杂质离子、锡泥、软熔、电解钝化等因素对电镀锡板表面黑灰程度的影响,综述了国内镀锡板黑灰的相关研究。讨论了黑灰缺陷对镀锡板涂饰性的影响。     

合金层白点的产生及其对镀锡板耐蚀性的影响

脱去镀铬板的自由锡层后，在锡铁合金层的表面目视发现了大量沿轧制方向伸展的白点，并且合金层的耐蚀性奠着白点数量与覆盖面积的增加而下降。采用扫描电镜(SEM)观察了合金层的形貌，用能谱(EDS)分析了白点与非白点处的成分，结果发现：白点处的合金层存在空洞，且铁的含量高于非白点处的含量。将表面带有大量白点的合金层进行14d的湿热实验后发现，在白点的边缘以及小白点处容易生锈，采用原子力显微镜(AFM)观察了锈点处的形貌，并解释了发生这一现象的原因。通过实验室模拟和现场数据的分析，找出了合金层表面白点产生的原因。     

镀锡钢板耐蚀性与恒电流阳极溶解电位-时间曲线的关系

在恒电流条件下，将镀锡钢板作为阳极在稀盐酸中用高电流密度电解。测定其电位E随时间t变化的曲线和相应的dE／dt-t微分曲线，从中抽取与镀锡钢板合金层致密程度和耐蚀性有关的参数，用支持向量机算法(support vector machine，SVM)和主成分分析(principal component analysis，PCA)及Fisher法等模式识别算法总结这些参数和镀锡钢板耐蚀性标准测试方法所得的合金-锡偶合电流值(alloy-tin couple value test，ATC值)的对应关系．据此找出耐蚀优级镀锡钢板E-t曲线判据和优化产品耐蚀性的工艺条件．结果表明：可在此基础上建立监测和优化镀锡钢板耐蚀性的快速测定方法．     

Cerium: a suitable green corrosion inhibitor for tinplate

In chloride solutions, tinplate exhibits localised corrosion processes due to the defects or imperfections of the outer Sn layer, which leaves the Sn-Fe alloyed layer exposed to aggressive solutions. The anodic character of the external Sn with respect to the internal alloyed layer, will lead to its dissolution acting as a sacrificial anode. The addition of cerium salts to the aggressive media decreases the pitting susceptibility of tinplate by means of cerium precipitation on the cathodic sites (bare Sn-Fe areas). This induces to a change of the controlling mechanism suggesting that cerium is a cathodic inhibitor for tinplate, which could be corroborated by removal selectively the outer Sn layer and leaving the Sn-Fe layer directly exposed to the solution. In these conditions, the corrosion process of the steel base will take place through the defects of the Sn-Fe layer, which presents a cathodic character in comparison to the base metal, inducing the precipitation of cerium on the alloyed layer.Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that the location of cerium precipitates depend on the distribution of the cathodic areas that could lead either to a continuous layer covering the surface or to precipitates inside the mechanical failures.     

Crystal orientation and corrosion resistance of CuNi10Fe1Mn alloy billet under rotating electromagnetic field

CuNi10Fe1Mn alloy billet under rotating electromagnetic field (REF) was characterized in this work. The change of the crystal orientation was first explored by X-ray diffraction (XRD) and scanning election microscope (SEM); the corrosion resistance was done by three electrodes system, and the natural sea water was used as corrosion medium. The results demonstrate that the strongest crystal orientation is transformed from crystal plane (200) to (111); moreover, the crystal plane (111) whose intensity is the strongest on the cross section and vertical section with REF causes the tubes be rolled easily, and the corrosion resistance of the billet is increasing with REF. As a result, properties of CuNi10Fe1Mn alloy tubes can be improved by REF.     

Effect of Al Content on the Corrosion Behavior of Extruded Dilute Mg-Al-Ca-Mn Alloy

The microstructure, extrusion texture and corrosion behavior of extruded dilute Mg-Al-Ca-Mn alloy with different Al contents were investigated. The corrosion rate of the alloy was more sensitive to the Fe impurities. The 1.2 wt% Al showed the lowest corrosion rate, which was mainly attributed to the weakening of the cathode effect caused by the increase of the Al and the decrease of the Fe in the precipitated phase. Refined grains, stronger basal surface texture and higher corrosion potential deriving from the higher Al content of the matrix also further enhanced the corrosion resistance of the matrix.     

The Effect of Texture on the Corrosion Behavior of AZ31?Mg Alloy

Magnesium (Mg) grains show anisotropic corrosion behavior, which implies that the single-phase, hot-rolled Mg alloy AZ31 sheet, if highly textured, will have different corrosion performance depending on its crystallographic orientation of the grains. Its rolling surface, dominated by (0001) basal crystallographic planes, is more corrosion resistant than its cross-section surface, which is mainly composed of $ \{ 10\overline{1} 0\} $ and $ \{ 11\overline{2} 0\} $ prismatic crystallographic planes. Furthermore, grain refinement by hot rolling is beneficial to the overall corrosion resistance of AZ31 because of the dissolution of AlMn(Fe) intermetallic precipitates in the alloy. Surface compressive deformation machining can lead to refined grains and an expected preferred grain orientation, thus improving the corrosion resistance of AZ31 alloy.     

铝合金稀土硝酸盐磷化的电化学行为

采用电化学测试和扫描电镜等方法研究了硝酸铈对6061 铝合金磷化过程及磷化膜形貌的影响。结果表明,硝酸铈的加入改变了铝合金基体与磷化液之间液固界面间的初始电位;硝酸铈吸附在铝合金表面上形成凝胶,成为磷酸盐晶体形成的良好晶核,磷化晶粒细化,生成较为致密的磷化膜,膜的耐蚀性得到提高。硝酸铈使铝合金达到最高电位的时间缩短,阴极极化电流密度增大,磷化速度加快。硝酸铈在整个铝合金磷化过程中起到了成核和促进的作用。在本实验条件下,最佳硝酸盐含量为20 mg/L～40 mg/L。     

退火孪晶对hcp结构二元镁锂合金腐蚀行为的影响

采用浸泡实验、电化学实验、腐蚀形貌观察以及扫描开尔文探针测试等实验方法对挤压态和退火态二元Mg-xLi（x=1,3,5,质量分数,%）合金的耐腐蚀性能进行研究。结果表明：挤压态Mg-Li合金经350 ℃/4 h退火处理后,可在基体中形成退火孪晶。在 0.1 mol/L NaCl溶液中,退火态合金的耐腐蚀性能明显劣于挤压态合金。通过扫描电子显微镜和激光共聚焦三维形貌分析,发现挤压态合金在腐蚀初期具有丝状腐蚀特征,并且随着腐蚀时间的延长形成了腐蚀坑;退火态合金表面发生快速腐蚀损伤,同时形成较大且深的腐蚀坑形貌。另外,退火态Mg-3Li合金的腐蚀等势线分布表明该合金退火孪晶区域优先发生了腐蚀溶解现象。因此,退火孪晶与母体晶粒之间可形成微电偶腐蚀效应,且退火孪晶区域充当阳极,母体晶粒作为阴极,从而降低了退火态Mg-Li合金的耐腐蚀性能。     

利用随机方法研究纳米化对纯锌点蚀行为的影响

选择柠檬酸型镀液,用脉冲电镀法成功制备纳米锌镀层;并用电化学法和随机法等研究纳米化对纯锌点蚀行为的影响.结果表明：纳米锌和铸态锌的点蚀击破电位均服从正态分布;纳米化增加了纯锌点蚀击破电位对电位扫描速度的敏感性,使纯锌的点蚀产生类型由B1（parallel）型转为B2（series）型,并能抑制纯锌的点蚀生长.