热镀锌层在模拟湿热酸性大气环境中的耐蚀性研究

目的研究Q420钢表面热镀锌工艺中,Zn和Zn-Al-Ni-RE合金镀层在酸性铜离子加速盐雾试验条件下的耐蚀性能。方法 Q420钢表面预处理后进行热镀锌,根据GB 6460—1986进行铜加速醋酸盐雾腐蚀试验,对比纯Zn镀层与Zn-Al-Ni-RE合金镀层的耐蚀性。结果 Ni,RE等元素的加入使镀层表面光亮,组织更加细密。在酸性铜离子加速实验进行到192 h时,纯锌镀层的腐蚀质量损失是合金镀层的2.7倍;72 h后纯锌镀层出现红锈,120 h后合金镀层出现红锈,说明Zn-Al-Ni-RE合金镀层比纯Zn镀层更耐腐蚀。结论通过适量添加Al,Ni与稀土元素,能使Q420钢合金镀层的耐蚀性能大幅度提高。     

带钢入锌锅温度对连续热镀锌层的影响

在带钢连续热镀锌工业化生产过程中,向锌液中添加少量Al,采用不同带钢入锌锅温度进行连续热镀锌。利用扫描电镜（SEM）和能谱仪（EDS）对热镀锌镀层的形貌、相结构和成分进行分析,研究带钢连续热镀锌过程中带钢入锌锅温度对镀层的影响。结果表明,带钢连续热镀锌过程中,向锌液中添加少量Al可使钢基板和锌镀层间形成Fe-Al中间层,抑制Fe-Zn合金层的形成,提高镀层的粘附性;而带钢入锌锅温度显著影响Fe-Al抑制层的结构,进而影响Fe-Zn合金层厚度,并最终影响镀层性能;对于试验钢DX51来说,当锌液中铝含量为0.18%,锌液温度为475 ℃时,带钢最佳入锌锅温度为495 ℃,此时镀层具有良好的粘附性。     

机械镀Zn-RE复合镀层的结构

以机械镀方法制备了Zn-RE复合镀层,采用SEM观察了镀层的结构,采用XRF、XPS分析了镀层表面的化学组成和镀层的表面化学状态,采用XRD分析了镀层的物相组成。结果表明,Zn-RE复合机械镀层主要由锌粉颗粒组成,稀土有利于镀层中的锌粉颗粒发生变形。镀层中主要含有Zn、Sn、Fe、La、Ce元素,其中La、Ce含量很低;Zn、Sn、Fe以单质态存在,La以La2O3存在。镀层表面主要由Zn、Sn、La、O组成,Zn以单质态存在,Sn以单质态和氧化态共存,La以La2O3存在。Zn-RE复合镀层形层过程中所添加混合稀土中的La未发生化学位态的变化。     

宁夏恒力4项科技成果入载年度公报

宁夏恒力钢丝绳股份有限公司研究开发的柔性抽油杆表面涂塑技术、高强度低松弛预应力螺旋肋钢丝、 4股钢丝绳 ,及与东北大学联合研究开发的锌铝镁稀土合金镀层钢丝通过了自治区科技厅组织的技术鉴定 ,并入载 2 0 0 0年宁夏回族自治区科学技术成果公报。锌铝镁稀土合金镀层钢丝经中科院腐蚀所中性盐雾试验、铜加速醋酸盐雾试验和电化学检测表明 ,合金镀锌层耐腐蚀性能明显优于纯锌镀层 ,可提高钢丝的使用寿命 ,具有很大的经济效益和社会效益。宁夏恒力钢丝绳股份有限公司将投资兴建年产 2 5万ｔ热镀锌铝镁稀土合金镀层钢丝、钢绞线项目 ,计…     

锌铝镀层热轧板的耐蚀性

采用扫描电子显微镜观察锌铝镀层热轧板表面形貌,并通过中性盐雾试验,研究了锌铝镀层热轧板耐蚀性。结果表明:镀锌铝工艺可以填补热轧板表面凹坑,使热轧板的耐蚀性显著提高;随着腐蚀时间的延长,锌铝镀层热轧板的腐蚀速率先增大后减小;5%白锈和5%红锈出现的时间约为第15天和第54天;结合试验数据建立的镀锌铝热轧板腐蚀动力学模型,与试验数据拟合程度较好,可以为锌铝镀层热轧板的腐蚀动力学定量分析提供理论依据。     

热浸Zn-Ti合金镀层的耐腐蚀性能

为了抑制热镀锌过程中因含硅活性钢引起的镀层超厚生长,采用在纯锌浴中加Ti的方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.采用浸泡腐蚀、电化学极化、交流阻抗以及X射线光电子能谱等方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.结果表明:Zn-Ti舍金镀层在5%NaCl溶液中的自发腐蚀倾向小于Zn镀层,其极化电阻和交流阻抗增大,腐蚀电流密度减小,耐蚀性能提高.Zn-Ti镀层表面形成的氧化膜由ZnO和TiO2组成.Zn-Ti合金镀层的耐腐蚀性能优于纯锌镀层是由于在镀层表面形成了更加稳定的TiO2膜.     

稀土锌铝合金在热镀锌钢管上的应用

为了降低锌耗,提高热镀锌钢管的防腐性能,增加经济效益,长春钢管总厂采取了在热镀锌液中加入微量稀土锌铝合金的方法。介绍了稀土锌铝合金镀管工艺流程,合金镀管镀层均匀性检验与盐雾检验的结果,并作了经济分析。通过应用稀土锌铝合金,可改善镀层合金金属的流动性,使镀层减薄 18％～ 20％,锌耗下降 10％,耐腐蚀性能提高 1～ 2倍,吨管节锌 8.2kg。     

高耐蚀性Zn-Mg合金镀层钢板的开

由于热镀锌钢板具有良好的耐蚀性 ,在土木建材行业已广泛地被使用。热镀锌钢板镀锌附着量 90～30 0ｇ/ｍ2 。在一般腐蚀环境下年腐蚀速度 5～ 10ｇ/ｍ2 ,在海岸地带年腐蚀速度 2 0～ 30ｇ/ｍ2 ,在盐分浓度高的地区热镀锌钢板耐蚀性较差。新日本制铁公司为了满足土木建材行业的需要 ,开发出高耐蚀性Ｚｎ Ｍｇ合金镀层钢板。对新开发Ｚｎ 0 .5 %Ｍｇ合金镀层钢板进行了海水喷雾试验 ,并以普通热镀Ｚｎ钢板作比较材。其结果新开发Ｚｎ 0 .5 %Ｍｇ合金镀层钢板产生红锈时间有明显延长 ,如在附着锌含量 4 5 0 ｇ/ｍ2 时 ,普通热镀钢板约10 0 0ｈ…     

Bi含量对热浸镀Zn-Bi合金镀层形貌和性能的影响

为了探索新的镀层成分,提高热镀锌层的性能,在锌液中加入不同含量的Bi,配制成Zn-x（x=0.1,0.2,0.3,0.4,0.5wt%）合金镀浴,并在20钢表面进行了热浸镀。采用金相显微镜、显微硬度计和全浸腐蚀试验对镀层形貌与性能进行了表征。结果表明,随着Bi含量的增加,Zn-Bi镀液的流动性提高,镀件表面的平整度和光亮度提高,镀层的纯锌层厚度减小,显微硬度降低,耐蚀性能变差。Bi     

电镀锌镍合金的盐水腐蚀行为

研究了电镀锌镍合金在5％NaCl溶液中的腐蚀行为。结果表明,12％～16％Ni镀层5％红锈出现时间是锌镀层的5倍,而且在腐蚀过程中出现腐蚀增重。SEM,EPMA,AES和XRD分析表明,锌镍合金镀层的高耐蚀性和腐蚀增重与生成粘附力强、绝缘性好的腐蚀产物ZnCl2·4Zn（OH）2有关。盐水腐蚀过程中未发现微裂纹,其腐蚀机理与盐雾腐蚀不同。     

彩色热镀锌工艺及镀层的抗蚀性能

通过镀液成分和工艺试验，筛选出Ｚｎ－Ｍｎ－Ｃｕ和Ｚｎ－Ｔｉ－Ｎｉ两种成分镀液，在一定的浸镀温度和冷却方式下，可以获得表面光滑，色泽均匀的彩虹，金黄，紫，蓝等彩色镀层。盐雾腐蚀试验表明；彩色热镀锌层比常规热镀锌层的耐蚀性能约提高一倍。     

La2O3对镍基合金激光熔覆层耐蚀性的影响

研究了Ｌａ２ｏ３对镍基合金激光熔覆层耐蚀性的影响,对加与不加Ｌａ２Ｏ３的激光熔覆试样进行了对比实验,研究结果表明,Ｌａ２Ｏ３的加入对激光熔覆层的组织起到了细化和净化作用。使熔覆层的二次枝晶间距减小,夹杂物含量降低,并明显提高了激光熔覆层的耐性能。     

Effect of silicate pretreatment, post-sealing and additives on corrosion resistance of phosphated galvanized steel

Sodium silicate （water glass） pretreatment before phosphating, silicate post-sealing after phosphating and adding silicate to a traditional phosphating solution were respectively carried out to obtain the improved phosphate coatings with high corrosion resistance and coverage on hot-dip galvanized（HDG） steel. The corrosion resistance, morphology and chemical composition of the coatings were investigated using neutral salt spray（NSS） tests, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results show that pretreatment HDG steel with silicate solutions, phosphate coatings with finer crystals and higher coverage are formed and the corrosion resistance is enhanced. Adding silicate to a traditional phosphating solution, the surface morphology of the coatings is nearly unchanged. The corrosion resistance of the coatings is mainly dependent on phosphating time. Phosphating for a longer time （such as 5 min）, the corrosion resistance, increasing with concentration of silicate, is improved significantly. Post-sealing the phosphated HDG steel with silicate solutions, the pores among the zinc phosphate crystals are sealed with the films containing Si, P, O and Zn and the continuous composite coatings are formed. The corrosion resistance of the composite coatings, related to the pH value, contents of hydrated gel of silica and Si2O^2- 5 and post-sealing time, is increased markedly. The improved coatings with optimal corrosion resistance are obtained for phosphating 5 min and post-sealing with 5 g/L silicate solution for 10 min.     

热镀锌层柠檬酸改进型铈盐转化膜的生长机理

将热镀锌钢板浸入含有25 g/L Ce(NO3)3·6H2O、4~6 g/L H2O2(30%)、15~20 g/L H3Cit的处理液中,在70℃下处理10 s~240 min,从而在其表面获得铈盐转化膜。采用中性盐雾试验(NSS)和电化学极化曲线来分析膜层耐蚀性能,确定最佳成膜时间范围。采用扫描电镜(SEM)观察膜层的微观形貌,利用能谱仪(EDS)、X射线光电子能谱仪(XPS)、红外吸收光谱仪(IR)分析膜层的化学组成。结果表明:处理时间为10 min左右的铈盐转化膜耐腐蚀性能最优,最佳工艺条件下得到的铈盐转化膜的耐蚀性能与铬酸盐转化膜的相当;随着处理时间的延长,膜的厚度增加,膜层的裂纹变宽;处理时间超过10 min后膜层逐步产生脱落,耐腐蚀性能也随之降低;转化膜的生长过程中,前期以柠檬酸铈吸附膜的沉积为主,后期以Ce(OH)3/Ce2O3及Ce(OH)4/CeO2的沉积占主导。     

Effect of porosity of phosphate coating on corrosion resistance of galvanized and phosphated steels Part II: Evaluation of corrosion resistance

The effect of porosity of phosphate coatings on the corrosion resistance of ungalvanized (UG), electrogalvanized, and hot dip galvanized steels is evaluated in this study. The corrosion resistance of phosphatized and painted steel is related to the integrity and continuity of phosphate and paint layers, and pores in the phosphate layer affect the corrosion resistance of material. The porosity of the phosphate coating was evaluated by using the cathodic polarization electrochemical test. To evaluate the corrosion resistance of the phosphatized and painted steels, they were submitted to accelerated corrosion tests. As was expected, the creepback from the scribe increased with the increase in porosity. This behavior was evident for UG steel, but less evident for galvanized steels due to cathodic protection and/or barrier effect of the zinc coating.     

Ra 及 Rpc 对无铬耐指纹热镀锌板表面性能的影响

目的研究热镀锌板表面平均粗糙度Ra和峰值数Rpc对无铬耐指纹热镀锌板表面耐指纹性、耐腐蚀性和涂装性的影响。方法将Ra=0.6~1.1μm和Rpc=55~100的热镀锌板制成耐指纹板,采用X射线光电子能谱仪分析其组成,采用分光光度仪分析其耐指纹性,采用硫酸铜混合溶液滴定和盐雾试验方法检测其耐腐蚀性,采用涂漆和冲击实验检测其涂装性。结果耐指纹膜和锌层表面形成Si—O—Zn金属键,耐指纹膜除了物理结合,还通过化学键合的方式与锌层表面结合。在充分交联固化和化学键合的情况下,无铬耐指纹热镀锌板耐指纹性不受热镀锌板Ra和Rpc的影响;热镀锌板Ra值越低,耐腐蚀性越好;耐指纹膜单位质量为1.1 g/m2,Ra≤1.1μm时,耐指纹板72 h盐雾试验白锈面积不大于5%;热镀锌板Rpc值越高,无铬耐指纹热镀锌板涂装性越好,Rpc≥80时,耐指纹热镀锌板涂漆冲压后,漆膜完好。结论 Ra和Rpc对热镀锌板耐指纹性影响不大,对耐磨蚀性和涂装性影响显著。     

Microbial corrosion resistance of galvanized coatings with 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one as a biocidal ingredient in electrolytes

Electrodeposition of galvanized coatings from electrolyte containing 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) can increase microbial corrosion resistance. Coatings were found to inhibit the growth and metabolism of sulphate-reducing bacteria (SRB). Open circuit potentials and corrosion rates of coupons revealed DCOIT effectively influences the coating property. Energy diffraction spectrum and infrared absorption spectra were used to detect DCOIT on the coating surface. Scanning electron microscopy and X-ray diffraction revealed morphological and structural modifications. Electrochemical impedance spectroscopy and polarization techniques determined the corrosion behaviour of coatings in SRB. Results showed coatings formed from electrolytes with DCOIT have improved microbial corrosion resistance and bactericidal action.     

涂膜破坏后膜下镀锌钢板大气腐蚀扩展研究

    通过SEM和EDS研究了带有划痕的涂装镀锌钢板在海洋大气环境下暴露一年半后,划痕周围涂膜下腐蚀产物的扩展行为,并分别对电镀锌、热镀锌、电镀锌预磷化的材料进行了耐蚀性比较.结果表明,在划痕周围涂膜下镀层的耐蚀性与镀层制作工艺无关,而与镀层厚度有关;涂膜前的预磷化对耐蚀性产生了不利影响;虽然涂膜与镀锌层间发生分离,但对镀层的耐蚀性没有产生影响;海洋大气环境存在的氯容易富集在腐蚀产物的前端,而硫则较均匀的分布在整个腐蚀产物转化区.     

Synergistic corrosion protection for galvanized steel by phosphating and sodium silicate post-sealing

To improve the corrosion resistance of phosphate coatings, the phosphated hot-dip galvanized (HDG) sheets were post-sealed with sodium silicate (water glass) solutions. The morphology and chemical composition of the composite coatings was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The effect of sodium silicate post-sealing treatment on the corrosion behaviors of phosphate coatings was investigated by neutral spray salt (NSS) tests and electrochemical measurements. The results show that after the silicate post-treatment the pores among zinc phosphate crystals are sealed with the films containing Si, P, O and Zn, leading to the formation of the continuous composite coatings on the surface of HDG steel. The corrosion resistance of the composite coatings depending on concentration of sodium silicate and post-sealing time is greatly improved by the silicate post-treatment. The optimum concentration of silicate and post-sealing time are 5 g/L and 10 min, respectively. Both the anodic and cathodic processes of zinc corrosion on the samples are suppressed conspicuously, and the synergistic protection effect of the single phosphate coatings and the single silicate films is evident. Moreover, the low frequency inductive loop in electrochemical impedance spectroscopy (EIS) is disappeared and the electrochemical impedance values are increased for more than one order of magnitude. The corrosion protection of the composite coatings is comparable to that provided by the chromic acid post-treatment.     

Si和RE对热浸铝镀层耐盐水腐蚀性能的影响

对铝浴中添加Ｓｉ和ＲＥ后批量热浸铝镀层的组织及耐盐水腐蚀性能的研究结果表明，铝浴中添加１￣７％Ｓｉ和适量ＲＥ，明显提高镀层耐腐蚀性能，减少镀层腐蚀速度随溶液温度升高而增加的幅度，但加入过量稀土则降低镀层耐蚀性，文中探讨了合金元素提高镀层耐蚀性能的原因。