共查询到19条相似文献,搜索用时 955 毫秒
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为找到在热浸镀钢材表面清洗处理过程中替代铬酸使用的缓蚀剂,通过质量损失测试、电化学测试和扫描电镜分析等方法研究了烟酸、吖啶和小檗碱对热浸镀5%铝-锌和55%铝-锌合金镀层在盐酸介质中的缓蚀作用。结果表明,3种杂环化合物在盐酸介质中对两种锌铝合金镀层均具有良好的缓蚀作用,其中小檗碱的缓蚀作用最好;它们通过单分子层、化学吸附方式吸附在镀层表面从而阻滞酸液对镀层的腐蚀,其吸附遵从Langmuir吸附等温式。在盐酸介质中,烟酸、吖啶和小檗碱对5%铝-锌和55%铝-锌合金镀层钢材均为有效的环境友好型缓蚀剂。 相似文献
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用盐雾试验和电化学阻抗谱法研究了热浸镀55%Al-Zn-1.6%Si合金镀层和某商用热浸镀锌层在5%NaCl溶液中的腐蚀行为,并用光学显微镜和扫描电镜分析了清除腐蚀产物后镀层表面组织形貌特征.结果表明,热浸镀55%Al-Zn-1.6%Si合金镀层耐盐雾腐蚀性约为商用热浸镀锌层的2.5倍.商用热浸镀锌层腐蚀表现出显著的扩散控制特征,而热浸镀55%Al-Zn-1.6%Si合金镀层腐蚀主要由电极表面电荷转移过程所控制. 相似文献
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用盐雾腐蚀和浸泡腐蚀两种方法对比研究了热浸镀55%Al-Zn镀层和Zn镀层在盐水环境中的腐蚀行为。用光学显微镜和扫描电子显微镜观察了清除腐蚀产物后镀层表面组织和横截面形貌特征。热浸镀55%Al-Zn镀层在盐雾腐蚀288h时的失重率约为Zn镀层的1/2,说明55%Al-Zn镀层具有更好的耐蚀性。用电化学阻抗谱方法分析镀层的腐蚀机理,认为55%Al-Zn镀层腐蚀前期由扩散控制,后期由于极化电阻的减小,电荷转移增多;而Zn镀层腐蚀前期是由于极化电阻减小,电极表面以电荷转移过程为主,后期表现出扩散特征。 相似文献
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目的 为详细研究热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气下的腐蚀行为及作用机理,同时为热浸镀Zn-Al-Mg镀层在湿热海洋大气环境中服役提供数据参考。方法 采用腐蚀失重、XRD、SEM、电化学等测试方法对热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气环境下的腐蚀行为进行研究。结果 腐蚀产物主要由Zn5(OH)8Cl2·H2O组成,腐蚀一段时间后,发现少量ZnO、Zn5(OH)6CO3,腐蚀产物具有与锌腐蚀类似的层状结构,1 848 h呈“三明治”型,相比于上下两层暗色物质,中层亮色腐蚀产物富集更多的Cl元素。热浸镀Zn-Al-Mg镀层腐蚀速率大体随时间延长呈上升趋势,只在672~840 h腐蚀速率下降,对比镀锌在模拟环境和锌在湿热大气环境中的腐蚀,热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气中表现出较好的耐蚀性。结论热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气下腐蚀产物演变与腐蚀过程中Mg的参与有关。腐蚀672~840h阶段腐蚀速率... 相似文献
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钢板热镀55%Al-Zn层的耐盐水腐蚀性能 总被引:4,自引:0,他引:4
采用全浸、半浸和盐雾等试验方法研究了钢板热镀55 %Al-Zn合金镀层在3%NaCl的盐水溶液中的腐蚀行为.观察分析了镀层的组织结构和在盐水中 腐蚀后的表面形貌及腐蚀产物,阐述了镀层在盐水中的腐蚀过程和机理.结果表明55%Al-Zn 合金镀层比Zn镀层更耐蚀,并同样具有Zn镀层对钢基体的保护能力. 相似文献
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综述了热浸镀Zn、Zn-Al和Zn-Al-Mg系合金镀层的性能特点和研究现状。在Zn-Al合金中添加Al元素可以减缓Zn的腐蚀氧化,同时可以在镀层表面形成致密的Al_2O_3薄膜起到屏蔽保护作用。在此基础上,采用Mg合金化,不仅可细化镀层组织,还可抑制疏松腐蚀产物的生成,进一步延长合金镀层的寿命。阐明了桥梁缆索用钢丝热浸镀工艺的特点和不足。采用中性盐雾试验评估了应力加载对桥梁缆索用热浸镀层组织和耐腐蚀性能的影响。应力加载会使镀层表面的腐蚀产物保护层破裂,加快腐蚀进程。同时指出了现有桥梁缆索用钢丝镀层评价标准尚存在一些争议,应结合现行的评价体系,重视讨论和探索新的更合适的评价标准。需要研究新一代(Zn-Al-Mg)合金镀层的制备技术和评价标准,推动具有高耐蚀性的多元合金镀层在桥梁缆索用钢丝上的推广应用。同时,桥梁缆索用钢丝热浸镀层的腐蚀性能应考虑应力加载下的腐蚀破坏和相关机理研究。 相似文献
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Al—Zn热浸镀层在H2S—NaCl—H2O体系中的腐蚀行为 总被引:3,自引:0,他引:3
采用表面钝化助镀法进行热浸镀,获得了55%Al-Zn镀层。研究了溶液温度、H2S浓度、NaCl浓度、pH值及试验时间对55%Al-Zn镀层在H2S-NaCl-H2O体系中的腐蚀行为。分析了镀层腐蚀前后的表面组织形貌及腐蚀产物,阐述了镀层的腐蚀机理。结果表明,55%Al-Zn镀层具有Zn镀层的电化学保护作用,其耐蚀性是镀锌钢的2-3倍,是风Q235的10-11倍。 相似文献
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B. Poulson 《工业材料与腐蚀》1987,38(7):359-367
An instance where a pre-commissioning hydrochloric acid clean caused localised corrosion of the heat-affected-zones (HAZ) in a carbon steel containing 0.25/0.3%C (ASTM Grade 210C) is described. The factors influencing the occurrence of corrosion at welds during chemical cleaning have been examined. In inhibited hydrochloric acid it has been shown that undesirably high weight losses are associated with pitting and a pitting potential below which pits will not initiate can be determined. Although the susceptibility to attack was different for welds in different steels, all steels were susceptible to localised attack. This susceptibility was reduced but not removed by a stress relieving post weld heat treatment. The use of inhibited citric acid, as an alternative acid cleaning solution, reduces but does not eliminate the possibility of localised weld corrosion. It is recommended that each material/weld combination be tested for susceptibility to localised attack prior to it being cleaned. This should be performed under dynamic conditions using a potentiostat or oxidising additions to examine how near the corrosion potential is to potentials promoting localised corrosion. 相似文献
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Influence of alloying elements on the passivation and the corrosion resistance of iron chromium base alloys The authors investigated the influence of cathodic alloying (with 0.1–0.5% Pd) on the passivation and the corrosion resistance of alloys of the system FeCr(25–100% Cr) and 25% Cr steels containing Mn, Ni, Mo and N; the experiments have been carried out in hot concentrated sulfuric acid and diluted hydrochloric acid solutions. It has been found that the addition of Pd as a cathodically active component considerably increases the autopassivation tendency as well as the corrosion resistance of the alloys under the particular conditions. Mn gives rise to improved autopassivation of austenitic and austenitic ferritic CrNi and CrNiMo steels, since it is catodically active, too. Cr steels cathodically alloyed with Pd acquire resistance to hydrochloric acid, too. 相似文献
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Corrosion resistance of unpainted and coil-coated sheets under atmospheric exposure An extensive study was carried out to compare the corrosion behaviour of unpainted and coil-coated hot dip galvanised and Galfan-coated sheets under atmospheric exposure. FIat and roll-formed test pieces with various metallic and organic coatings were exposed to atmospheric weathering at five different locations for 9 years. The corrosion behaviour of unpainted specimens was determined quantitatively by measuring the loss of metallic coating thickness and by visual assessment of red rust on surfaces and bends. In the case of organically coated specimens formation of red rust and blistering on surfaces and bends was assessed visually and creepage at scores and cut edges was measured. The results show that Galfan coatings are subject to much slower weathering than hot dip galvanised coatings. It is concluded that in most applications users could select the next lower coating thickness group when using Galfan instead of hot dip galvanised sheet. Visual assessment of corrosion damage (red rust, blisters, creepage) also leads to the overall conclusion that both unpainted and coil coated Galfan perform much better than hot dip galvanised sheet in natural weathering. The advantages of using Galfan especially for building applications are thus being established. 相似文献
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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. 相似文献
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Hot dip fine Zn and Zn-Al alloy double coating for corrosion resistance at coastal area 总被引:1,自引:0,他引:1
A new hot dip Zn-7Al alloy coating was performed on a structural steel by double coating of fine Zn and Zn-7 wt.% Al alloy, to prevent severe corrosion in coastal area. The alloy-coated steels were exposed to seaside, quasi-industrial, and rural districts to compare with conventional Zn coating. Double coating was significantly effective in preventing corrosion, particularly in a seaside. It was estimated from the exposure test for 10 years that the life of the Zn-7Al alloy-coated steel would be almost four times that of the Zn-coated steel in the seaside. A bending test showed that no exfoliation occurred at the interface between the coated alloy and substrate steel. TEM observation revealed that the excellent adhesiveness of the doubly coated fine Zn and Zn-7Al alloy to the steel substrate was due to formation of the interface region consisting of heterogeneous fine phase mixture of zinc, aluminium and iron. 相似文献
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环保节能领域光伏支架用有锌花镀锌产品是邯钢市场开发的重点,但用户对其表面质量、力学性能、耐蚀性能和变形延展性有较高的要求。从热轧备料,酸洗工艺,热镀锌退火温度及锌层控制等方面阐述了开发光伏支架用热镀锌S390GD(S450GD)+Z产品的质量保证措施。通过降C、增Mn的化学成分设计,板坯出炉温度1 100~1 150℃、粗轧压下率40%~45%、终轧温度(850±20)℃、卷取温度降至(580±20)℃ 的热轧工艺优化,保证了热轧原料强度。通过酸液温度、酸洗速度、缓蚀剂添加量的优化,以及热镀锌退火温度、锌液成分的优化改进,实现了锌花结晶均匀性控制,产品质量满足用户要求。 相似文献