共查询到19条相似文献,搜索用时 156 毫秒
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应用4×4阵列丝束电极模拟研究了混凝土中钢筋的腐蚀.将混凝土试样浸泡在浓度为1.9m01/L的NaCI溶液中,通过测量铁丝束电极的自腐蚀电位,获得在不同埋置深度时,铁丝腐蚀的电位分布信息;并研究了加入不同水泥添加剂对水泥性能影响的电化学行为.结果表明,普通混凝土中铁丝腐蚀不均匀,自腐蚀电位较分散.电位随时间负移.加入0.25%木质磺酸钠,铁丝自腐蚀电位负移量减少,腐蚀程度显著下降;加入0.34%苯甲酸钠,铁丝自腐蚀电位负移量比加入木质磺酸钠更少,铁丝的腐蚀程度明显减少;当混凝土中同时添加0.25%木质磺酸钠和0.34%苯甲酸钠时,电位负移速度减缓,但达不到单独添加木质磺酸钠或苯甲酸钠时的防腐效果.比较得出,单独加入苯甲酸钠防腐效果最好. 相似文献
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应用3x3矩列丝来电极模拟研究混凝土中钢筋的腐蚀情况。将混凝土试样(空白样和加入粉煤灰的混凝土样)分别都浸泡在1.7mol/LNaCl溶液中,通过测量铁丝来电极的自腐蚀电位,获得了在不同埋置深度时,铁丝腐蚀的电位分布信息。结果表明:(1)普通混凝土中铁丝腐蚀不均匀,自腐蚀电位较分散,电位随时间负移;(2)加入粉煤灰后,铁丝自腐蚀电位负移量减少,腐蚀程度显著下降,因此粉煤灰能有效提高混凝土中钢筋的抗锈蚀能力。 相似文献
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针对混凝土结构中钢筋的锈蚀问题,以普通硅酸盐水泥和镁水泥作为胶凝材料,制作了钢筋裸露和涂有环氧树脂涂层的4种钢筋混凝土试件,将其浸泡在氯盐、硫酸盐及镁盐的耦合溶液中,利用电化学方法得到极化曲线和交流阻抗谱,通过塔菲尔外推法进行非线性最小二乘法拟合计算得到腐蚀电流密度、腐蚀电位、腐蚀速率等相关评价指标来衡量混凝土中钢筋锈蚀情况.结果表明:长期浸泡在耦合盐溶液中,普通硅酸盐水泥和镁水泥钢筋混凝土试件都发生了较严重的腐蚀,普通硅酸盐水泥的抗腐蚀性优于镁水泥;在钢筋表面涂有GHT涂层可极大地降低钢筋的腐蚀速率;镁水泥GHT涂层混凝土试件的抗腐蚀性能劣于硅酸盐GHT涂层混凝土试件但优于硅酸盐裸露钢筋混凝土. 相似文献
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采用线性极化法研究了电化学氯离子萃取处理后砂浆中已被氯离子侵蚀的钢筋的再钝化.研究表明:应用电化学氯离子萃取(electrochemical chloride extraction,ECE)后60d,钢筋经去极化和再钝化,腐蚀电位升高到-200mV以上,与基准试件低于-400mV的电位相比,腐蚀概率大为降低:腐蚀电流密度的变化规律与腐蚀电位相似,ECE时钢筋腐蚀电流密度仍较高,60 d后则降到安全的范围内.经ECE处理后,钢筋腐蚀电位和腐蚀电流密度的变化表明钢筋经过了再钝化,有效地抑制已被氯离子侵蚀的钢筋进一步腐蚀. 相似文献
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针对镁水泥混凝土自身氯离子对钢筋的腐蚀而降低了镁水泥钢筋混凝土工作寿命的问题,提出利用久美特涂层来缓解氯盐对钢筋的腐蚀作用.试验通过利用电化学工作站对久美特涂层钢筋的镁水泥钢筋混凝土试件在自然环境下和水环境以及氯化镁溶液中的极化曲线进行分析.结果表明:通过对腐蚀电流密度和腐蚀电位的分析得导出久美特涂层可以很好的保护镁水泥钢筋混凝土中的钢筋免受腐蚀,并且混凝土保护层厚度越大钢筋的腐蚀电流密度就越小.在最后腐蚀达到稳定后,久美特涂层钢筋腐蚀电流密度的数量级是钢筋无锈蚀时的100分之一,从而得出久美特涂层对镁水泥钢筋混凝土中的钢筋起到很好的保护作用,使得镁水泥混凝土在盐渍土中依然可以拥有很好的工作性能. 相似文献
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利用丝束电极技术研究0.1~0.3 mm裂缝砂浆保护下电极表面腐蚀电流分布与电化学阻抗谱。在海洋浪溅区对0.1~0.3 mm裂缝混凝土暴露700d,测试钢筋混凝土阻抗谱并计算腐蚀电流演变。结果表明:无裂缝砂浆中钢筋钝化时间大约为10~17 d,裂缝使得混凝土中钢筋钝化时间提前。混凝土中钢筋钝化与锈蚀均是由点到面的非均匀过程,裂缝使得氧气快速渗透至钢筋表面并在裂缝处形成阴极区;随着氯离子通过裂缝扩散至钢筋,裂缝处钢筋氧化形成若干阳极区。当横向裂缝小于0.1 mm时,海洋环境下的混凝土微细裂缝自愈合降低了氧气供给,使得裂缝处阳极区再次转化为阴极区从而延缓钢筋腐蚀。当横向裂缝为0.3 mm时,混凝土裂缝处钢筋快速锈蚀并向裂缝两边扩展,海洋浪溅区钢筋腐蚀速度可达到0.484μm/a。 相似文献
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应用电化学方法测试了不同氯盐含量混凝土试件在表面涂覆迁移性阻锈剂(MCI)后不同时刻钢筋的腐蚀电流密度,应用MCI渗透模型,计算不同渗透时间钢筋界面区的阻锈剂浓度,利用统计产品与服务解决方案软件SPSS(Statistical Product and Service Solutions)进行多元非线性统计分析,得到了混凝土中钢筋腐蚀电流密度与界面区MCI浓度、水溶性氯离子含量的量化模型,应用该模型并根据Broomfield准则,计算出使不同氯盐含量混凝土中锈蚀钢筋腐蚀速率降低到钝化状态所需的临界MCI浓度,进而确定在混凝土表面MCI的涂覆量。采用Java语言进行计算机编程,根据混凝土强度(孔隙率)、混凝土水饱和度、水溶性氯离子含量、钢筋锈蚀程度及保护层厚度等参数,计算并输出使混凝土中锈蚀钢筋腐蚀速率降低到钝化状态所需的MCI涂覆量及涂覆工艺。 相似文献
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针对因钢筋腐蚀而造成镁水泥钢筋混凝土使用寿命较短的问题,制备不同涂层钢筋的镁水泥混凝土试件,通过CS350工作站及其分析软件对不同龄期试件进行测试分析,根据腐蚀电位、腐蚀电流密度、腐蚀速率及涂层电阻等电化学参数,衡量同种涂层钢筋在不同环境下的抗腐蚀性能.结果表明:锌美特涂层在三种环境下均出现低腐蚀现象,且室内自然环境下腐蚀情况最轻、自然水浸泡环境下次之,氯盐浸泡环境下最差.美加力涂层与久美特涂层在三种环境下均未出现腐蚀现象,且室内自然环境下抗腐蚀性能最好、氯盐浸泡环境下次之、自然水浸泡环境下最差;三种环境下涂层钢筋防腐性能均为:久美特涂层钢筋最好、美加力涂层钢筋次之、锌美特涂层钢筋最差;涂层钢筋在不同环境下虽然抗腐蚀性能不同,但涂层技术均可以延长镁水泥钢筋混凝土构件的使用寿命. 相似文献
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用钝化剂TRI-V 120、TRI-V 121和SpectraMATETM 25分别对碱性无氰镀锌层进行钝化,考察了钝化层在不同pH的1%(质量分数)NaCl溶液中的开路电位随时间的变化.结果表明,开路电位变化受溶液pH的影响.在pH=3时,镀锌钝化层的开路电位随时间呈规律性变化:开始电位较高,反映了完整钝化层的电极电位;随后逐渐变负,反映了钝化膜的溶解过程;最后处在锌的电极电位范围,反映了钝化膜已经完全溶解.对比盐雾试验结果后发现,从钝化膜电位变化到锌电极电位所需的时间能够反映钝化膜的稳定性,即时间越长,耐蚀性能越好.因此,开路电位测量法能够快速评价镀锌钝化层的耐蚀性. 相似文献
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Electrochemical behavior of mild steel in concrete: Influence of pH and carbonate content of concrete pore solution 总被引:1,自引:0,他引:1
The increase of the rebars corrosion rate due to the concrete carbonation is the major cause of reinforced concrete degradation. The aim of this study was to investigate the transition from passive to active corrosion of mild steel rebars in carbonated concrete. For this purpose, electrochemical techniques (polarization curves, free corrosion potential measurements) and surface analyses (EDS, XRD, XPS) were used. Five different electrolytes, with pH ranging from 13 to 8.3, were chosen to simulate the interstitial concrete pore water at various degrees of carbonation. The results indicate that the transition pH is between 10 and 9.4. XPS results indicate a passivation of mild steel for pH values ranging from 13 to 10 due to the formation of a thin iron III oxide layer. Immersion tests highlight the importance of the buffering effect of the carbonate content. At the free corrosion potential in an aerated solution, a decrease of the carbonate content increases the corrosion rate. On the opposite, at low electrode potential, the kinetics of oxidation increases with the carbonate content. 相似文献
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The effect of surface preparation on electroless Ni‐P plating on carbon fiber reinforced cyanate ester resin laminate has been investigated. Three different surface chemical etching ways were performed, namely: (i) hexanediamine etching, (ii) hexanediamine followed by aniline etching, and (iii) aniline etching. The results indicated that Ni‐P coating on hexanediamine etching or hexanediamine followed by aniline etching pretreated carbon fiber reinforced cyanate ester resin laminates usually tended to be cracked, veined, and low adhesion, while aniline etched laminates showed a homogenous roughing surface which is suitable for subsequently uniform, cellular, and good adhesion Ni‐P plating. POLYM. COMPOS., 37:1161–1166, 2016. © 2014 Society of Plastics Engineers 相似文献
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I Fernández‐Olmo A Ortiz A Urtiaga I Ortiz 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(12):1616-1622
BACKGROUND: Post‐treatment of zinc plated surfaces is required to provide corrosion protection; for this purpose chromium passivation is usually used. In the EU, the older hexavalent chromium passivation baths have been replaced by trivalent chromium conversion coatings. However, the life of Cr(III) passivation baths is reduced due to iron and zinc impurities generated in the process. Thus, the objective of this work was to investigate the regeneration of spent passivation baths from the plating industry by ion exchange using a new chelating resin (Purolite S‐957). RESULTS: Three genuine passivation baths with different iron and zinc concentrations were investigated; the effect of loading flow rate, temperature and resin regeneration conditions on the uptake of iron ions was also studied. The removal performance of iron was increased at higher temperature (55 °C) and lower flow rates. The best regeneration conditions were found to be 6 bed volumes (BV) of 30 wt% HCl. CONCLUSION: This work has shown that iron can be selectively removed from trivalent chromium passivation baths using a new chelating resin (Purolite S‐957) and no addition of chromium (III) is required. Low feed flow rate and high bath temperature (up to 55 °C) are recommended for high iron uptake. Copyright © 2008 Society of Chemical Industry 相似文献
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介绍了电泳槽玻璃钢衬里施工的流程,包括材料的表面处理,刷底漆,涂防腐树脂,贴增强纤维布,树脂积层,防腐面处理,涂面层,检查及养护固化.指出了在材料检验、施工管理及安全防护等方面的注意事项.给出了玻璃钢涂层的检测步骤. 相似文献
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The iron dissolution and passivation was studied in sulphate solution containing different oxygen concentrations and within the range 3 < pH < 6. The measurements were carried out cyclic voltammetrically and under steady-state polarization conditions using a rotating disc electrode of highly pure recrystallized iron. The obtained kinetic data can be explained mainly by the iron dissolution and passivation mechanism proposed previously for oxygen free solutions. This mechanism is characterized by the formation of different oxide intermediates [Fe(OH)n]ads, with n = 1,2,3 depending on the pH and the potential. Above a critical pH-value, the diffusion controlled oxygen reduction is the dominating cathodic process, and the anodic iron dissolution and passivation is inhibited by the time-dependent formation of three-dimensional porous oxide layers on the electrode surface. In neutral solutions the iron dissolution and passivation mechanism turns to that encountered in alkaline media. 相似文献