发表在《期刊》上的最新研究Metals查看拉伸压力和无压力碳钢的电化学影响,以及在建模的混凝土孔隙液中张力对钢钝化和生锈行为的影响。
学习:Galvanic Corrosion Study between Tensile-Stressed and Non-Stressed Carbon Steels in Simulated Concrete Pore Solution。Image Credit: P. Thungsarn
碳钢及其利用
碳钢是一种铁碳合金,碳含量高达2.1%。碳钢中额外合金的额外合金没有最小的比例,但是经常包含的元素是锰。碳钢根据其热量价值分为三种类型:低碳钢,中碳钢和高碳钢。低碳钢经常用于车身部位,结构形式,管道,建筑物和食品罐中。
中碳钢通常用于铁轨,机车轮胎,发动机组件,变速箱和工程产品,因为它们的高韧性,耐磨性和耐用性。高碳钢由于其高摩擦系数和刚度而用于金属切割,弹簧,巨型电线和铸件中。
压力的影响
External stress increases forceful chemical infiltration owing to the production of fractures at aggregate/paste contacts (i.e., continual microcracks), reducing the performance of the concrete. Despite the damage in concrete, stress affects the corrosive rate of steel. Under stress, the erosion dynamics can change, potentially because of localized lattice distortion and increased kinetic energy.
当钢暴露于水泥的碱性条件下时,其表面会形成潜在涂层。拉伸应力可能会导致钢的被动氧化物涂层的微观裂纹,而压缩应力可能会导致保护膜和钢基材之间的分层。
结果,在应力下向钢的氧化物层分层是可能的。在压缩应力的影响方面,应力条件下的钢在经历含氯化物的气氛时的表现优于卸载钢。
等效电路用于模拟混凝土孔溶液中钢的行为。图片来源:Dong等。al。,金属
电效应
The galvanic effect refers to corrosive harm caused by the coupling of two different metals in the presence of an electrolyte. It happens when two (or more) different metals make electrical contact beneath the water. When two different metals are submerged in a conductive fluid and electronically linked, galvanic corrosion develops.
One metal is shielded (the cathode), while the other (the anode) is eroded. To minimize the galvanic effect, using materials with equal corrosive capabilities and disconnecting the electrical connection using insulation is effective. Apart from this, the inclusion of corrosion inhibitors, coating the materials, and the inclusion of sacrificial material may play their part in minimizing this harmful phenomenon.
Experimental Conditions
C-shape samples have been frequently employed in assessing metallic stress corrosion. The exposed portion in a C-shape carbon steel alloys experienced the highest tensile stress value.
C形碳钢的示意图。图片来源:Dong等。al。,金属
除裸露区域外,样品的面上覆盖了三层环氧树脂。唯一样品用于创建具有应力水平的集合(σy)分别标记为A0,A3,A5和A10的0%,33%,55%和100%的屈服应力(Y)。为了模仿混凝土微环境,采用合成混凝土孔溶液(SCP)作为溶液。每三天使用饱和钙胶电极(SCE)作为测试集对标本的开路电势(OCP)值进行一次监测。使用电化学阻抗光谱法(EIS)方法研究了两个特定样品的氧化和腐蚀特性。
Research Findings
在钢的SCPS钝化过程中,FE首先被氧化以产生Fe(II)和Fe(III)氧化物的复合物。氧化物膜电阻率的时间依赖性变化的发现(Ro)and the impedance of the charge transfer (RCT)表明氯化物的含有降低了RO和RCT。After the injection of chlorides, the charge transport impedance of tensile-stressed steels dropped precipitously, finally yielding a similar or even lower value of RCT比无压力钢的0)。
在各种应力水平上的氧化物膜(A)和电荷转移(B)的电阻。图片来源:Dong等。al。,金属
随着拉伸应力的增加,注意到混凝土基质中被动膜电阻(RO)的降低。在不含氯化物和氯化物污染的SCPS中,RO下降,因为应力的拉伸值升至。加入3%wt之后。氯化钠百分比占个别钢试样,电荷转移耐药性显着降低(RCT)was frequently found.
通过电化学,最新的研究探讨了SCP中拉伸压力和无压力钢的电腐蚀,以及拉伸应力对钢的腐蚀行为的影响。将来,需要长期检查应变和无压力钢之间的电腐蚀。
Further Reading
Dong et. al. Galvanic Corrosion Study between Tensile-Stressed and Non-Stressed Carbon Steels in Simulated Concrete Pore Solution. Metals. 2022; 12(1). 98. Available at:https://www.mdpi.com/2075-4701/12/1/98
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