添加不同稀土元素对固体包埋法在304不锈钢表面制备Ti/Cr-RE双层涂层电化学性能的影响

Influence of Adding Various Rare Earth Elements on Electrochemical Corrosion Resistance of Ti / Cr-RE Coatings Fabricated on 304 Stainless Steel by Pack Cementation

目的选择合适的稀土制备Ti/Cr-RE双层涂层,提高不锈钢的耐腐蚀性能。方法采用两步粉末包埋法,先在304不锈钢表面渗Ti,再制备稀土改性Cr涂层,获得Ti/Cr-RE双层涂层。通过添加不同的稀土氧化物Y2O3和Ce O2,获得两种双层涂层,对比分析涂层的表面形貌、断面形貌及物相组成,利用电化学测试方法测定304不锈钢基体及两种Ti/Cr-RE双层涂层在3.5%(质量分数)Na Cl溶液中的电化学腐蚀性能。结果添加不同稀土元素钇、铈,都能在渗Ti不锈钢表面形成一层致密、连续的稀土改性渗铬层。在两种稀土元素改性的Cr涂层中,稀土元素分别与Cr,Fe,Ni,Ti形成了金属间化合物。304不锈钢基体的自腐蚀电位为-0.324 V,腐蚀电流密度为0.1363μA/cm2;钇改性铬涂层的自腐蚀电位为-0.341 V,腐蚀电流密度为0.2058μA/cm2;铈改性铬涂层则具有更高的自腐蚀电位(-0.263 V)及更低的腐蚀电流密度(0.030 86μA/cm2)。结论钇改性铬涂层不能提高304不锈钢基体的耐腐蚀性能,铈改性铬涂层可以明显提高基体的耐腐蚀性能。

Objective To prepare Ti / Cr-RE coatings on 304 stainless steel with suitable rare earth elements so as to improve corrosion resistance of stainless steel. Methods The Ti coating and Cr-RE coating were deposited on 304 stainless steel successively via pack cementation. In order to obtain two different Ti / Cr-RE coatings,Y2O3 and Ce O2 were used as RE sources. The sample surface and cross-sectional micrographs were investigated by scanning electron microscopy（ SEM）. The phase composition of sample surface was detected by X-ray diffraction（ XRD）. Electrochemical experiments were carried out to investigate the corrosion resistance of the 304 stainless steel substrate and the two kinds of Ti / Cr-RE double-layer coating in 3. 5% Na Cl solution. Results It was concluded from all the outcomes that the dense and continuous Cr-RE coatings can be formed on the Ti stainless steel by adding rare earth elements Y and Ce. In the two kinds of Cr coatings modified by rare earth elements,intermetallic compounds were formed from the rare earth elements with Cr,Fe,Ni,and Ti respectively. The corresponding corrosion potential of 304 stainless steel was- 0. 324 V,and the corrosion current density was 0. 1363 μA / cm2. The corresponding corrosion potential of Cr-Y coating was- 0. 341 V and the corrosion current density was 0. 2058 μA / cm2,while the Cr-Ce coating presented higher corresponding corrosion potential of- 0. 263 V and lower corrosion current density of 0. 030 86 μA / cm2. Conclusion The Cr-Y coating does not show a promotion in electrochemical corrosion resistance compared with 304 stainless steel,while the Cr-Ce coating presents a good performance in electrochemical corrosion resistance in 3. 5% Na Cl solution.