Fe32Mn3Al8Cr反铁磁精密电阻合金Al_2O_3防护涂层的研究

Protective Al_2O_3 Coating on Antiferromagnetic Fe32Mn3Al8Cr Precise Resistance Alloy

用溶胶-凝胶法在Fe32Mn3Al8Cr反铁磁精密电阻合金表面提拉制备Al2O3耐腐蚀防护涂层.采用X射线衍射分析涂层相结构,扫描电镜观察涂层表面形貌.在Fe32Mn3Al8Cr合金表面形成连续、光滑的Al2O3涂层,具有(110)择优取向的γ-Al2O3结构.采用动电位阳极极化法测定涂层的电化学腐蚀性能表明,与原始合金相比较,在1 mol/L Na2SO4溶液中,Al2O3涂层的自腐蚀电位提高了571 mV,自腐蚀电流密度降低了1个数量级以上,维钝电流密度降低了近1个数量级;在1%NaCl溶液中,自腐蚀电位与原始合金相当,自腐蚀电流密度降低了2个数量级,腐蚀电位高达2000 mV(SCE)时仍未发生孔蚀击穿.而且,Al2O3防护涂层的耐均匀腐蚀和耐孔蚀性能均优于1Cr18Ni9Ti奥氏体钢.

A protective Al203 coating on the antiferromagnetic Fe32Mn3A18Cr precise resistance alloy was prepared by sol-gel method with dip-coating process. The structure and surface morphologies of the Al2O3 coating were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The continuous and smooth coating on the precise resistance alloy is composed of γ-Al2O3 phase with a （110） preferred orientation. The potentiodynamic anodic polarization measurement indicates that the Al2O3 coating has a lower passivated current density by one order of magnitude in 1 mol/L Na2SO4 solution, compared with the original alloy. In 1% NaCl solution, its corrosion potential is equivalent to the original alloy, but its corrosion current density is decreased by two orders of magnitude with no pitting corrosion at the passive potential up to 2 000 mV（SCE）. Moreover, the protective γ-Al2O3 coating has the better general and pitting corrosion resistance than the 1Cr18Ni9Ti austenite steel does.