核桃青皮提取物对NH2SO3H溶液中冷轧钢的缓蚀作用研究

Inhibition Effect of Walnut Green Husk Extract on Steel in NH2SO3H Solution

采用体积分数为40%的乙醇为浸提溶剂,从核桃青皮原料中提取制备核桃青皮提取物,采用失重法和电化学法测试研究了核桃青皮提取物对冷轧钢在NH2SO3H溶液中的缓蚀作用,并用扫描电子显微镜研究了钢表面的微观形貌。结果表明:核桃青皮提取物对冷轧钢在0.10 mol/L NH2SO3H溶液中产生了显著的缓蚀作用;缓蚀率随着核桃青皮提取物浓度用量的增加而增大,且随温度的持续升高而不断增强。核桃青皮提取物主要通过物理和化学混合吸附在钢表面发生吸附,且吸附行为服从Langmuir吸附等温式;核桃青皮提取物同时减缓了氨基磺酸对冷轧钢阴阳两极的腐蚀反应速率,属于混合抑制型缓蚀剂。Nyquist谱图呈弥散容抗弧,其电荷转移电阻随核桃青皮提取物浓度用量的增加而显著增大。电子显微镜扫描结果,可明显观察到添加核桃青皮提取物后的钢表面腐蚀程度显著减弱。

Walnut green husk extract was extracted and prepared by using the extraction solvent of ethanol water solution(volume fraction is 40%).The inhibition effect of walnut green husk extract on the corrosion of cold rolled steel in sulfamic acid(NH2SO3H)solution was studied by weight loss method and electrochemical techniques.Scanning electron microscope(SEM)was used to examine the micro-graphs of steel surfaces.The results show that walnut green husk extract exhibits evident inhibitive performance on the corrosion of cold rolled steel in 0.10 mol/L NH2SO3H.Inhibition efficiency remarkably increases with the increase of the concentration of walnut green husk extract,and improves with an increase in temperature.Walnut green husk extract can adsorb on steel surface via mainly the mixed-adsorption mode of physisorption and chemisorption,and its adsorption behavior obeys Langmuir adsorption isotherm.The addition of walnut green husk extract drastically inhibits both anodic and cathodic reactions for the corrosion of sulfamic acid on steel,and can be arranged as a mixed-type inhib-itor.Nyquist appears an individual depressed capacitive loop,and the charge transfer resistance increases with the increase of walnut green husk extract concentration.Inspection of the SEM micrographs of corroded steel surface reveals that WGHI can efficiently retard the corrosion of steel surface.