新型热扩散法制备耐海洋环境腐蚀钢筋及其耐蚀性

A Novel Thermal Diffusion Method to Produce Marine Corrosion Resistant Steel Bar and Its Corrosion Resistance

通过热扩散工艺在自行研制的钢筋原坯表面形成一层化学成分满足不锈钢要求且耐蚀性能优异的"类不锈钢"表面层。采用XRD、SEM及EDS对热扩散层的相结构、表面形貌和截面成分分布进行了分析和表征。通过浸泡加速腐蚀试验、动电位极化曲线和电化学阻抗谱研究了HRB400、316L以及"类不锈钢"钢筋试样在含氯离子混凝土模拟孔隙液中的腐蚀行为及规律。结果表明,热扩散层主要由Cr_(23)C_6、Fe-Cr和Cr_2N等相组成。在含有氯离子的混凝土模拟孔隙液中,"类不锈钢"钢筋的耐蚀性比HRB400提高了287.4倍,比316L提高了1.4倍。"类不锈钢"钢筋的腐蚀电流密度是HRB400的1/299,是316L的1/223。"类不锈钢"钢筋的极化电阻R_p值是HRB400的28.7倍,是316L的4.5倍。因此,"类不锈钢"钢筋在混凝土模拟孔隙液中的耐氯离子腐蚀性能优于316L和HRB400。

The thermal diffusion treatment was performed on a self-developed steel bar to form a stainless-steel-like surface layer with stainless steel chemical composition and excellent corrosion resistance. The phase structure, surface morphology and cross-section composition distribution of the thermal diffusion layer were analyzed and characterized by XRD, SEM and EDS. Immersion test, potentiodynamic polarization and electrochemical impedance spectroscopy were used to study the corrosion behavior and mechanisms of HRB400, 316L and stainless-steel-like steel bar in simulated concrete pore solution with chloride ions. Results show that the thermal diffusion layer is mainly composed of Cr23C6, Fe-Cr and Cr2N phases. In simulated concrete pore solution with chloride ions, the corrosion resistance of stainless-steel-like steel bar is 287.4 times better than HRB400, and 1.4 times better than 316L. The corrosion current density of stainless-steel-like steel bar is 1/299 of HRB400 and 1/223 of 316L. The polarization resistance Rp of stainless-steel-like steel bar is 28.7 times larger than that of HRB400 and 4.5 times larger than that of 316L. Therefore, the corrosion resistance of stainless-steel-like steel bar in simulated concrete pore solution with chloride ions is obviously better than that of 316L and HRB400.