CLAM钢表面铝化物涂层的制备与铅液相容性研究

目的探索铝化物涂层的制备工艺,研究其是否能有效抑制铅液对CLAM钢的腐蚀。方法用配制的渗剂对CLAM钢进行包埋渗铝,并通过随后的热扩散和原位氧化处理,在CLAM钢表面制备铝化物涂层,研究不同渗铝时间和热扩散时间对涂层厚度的影响。通过静态氧化试验和铅液腐蚀试验,分别评价铝化物涂层的抗氧化性能及其与铅液的相容性,采用XRD、SEM和EPMA分析涂层的相组成以及铅液腐蚀前后的微观形貌和元素分布。结果包埋渗铝+热扩散+原位氧化处理制备的铝化物涂层主要由约30μm的FeAl相层和约70μm的α-Fe(Al)固溶体层组成。在热处理过程中,由于Al和Fe的互扩散现象,涂层中的Fe-Al相依次经过了Fe₂Al₅、FeAl₂、FeAl、Fe₃Al和α-Fe(Al)的转变。在600℃空气中静态氧化120 h后,铝化物涂层试样氧化质量增量为0.028 mg/cm²,比CLAM钢的氧化质量增量降低了1个数量级,铝化物涂层使CLAM钢的氧化动力学曲线由直线规律转变为抛物线规律。经550℃铅液腐蚀600、1800 h后,铝化物涂层的腐蚀质量增量分别为0.058、0.077 mg/cm²,仅约为CLAM钢的1/120。CLAM钢表面产生了疏松多孔的铁氧化物层,而铝化物涂层没有发生明显的腐蚀,但是腐蚀1800 h后,随着表面铝含量的不断消耗,Al₂O₃层厚度逐渐减小。结论铝化物涂层具有良好的抗氧化性能及与铅液的相容性,能够有效抑制铅液对CLAM钢的腐蚀。

Preparation of Aluminide Coating on CLAM Steel Surface and Compatibility with Liquid Lead

This paper is to explore the preparation process of aluminide coating and study whether it can effectively inhibit the corrosion of liquid lead to CLAM steel.The aluminide coating was prepared on the surface of CLAM steel by pack cementation with the formulated penetrant and subsequent thermal diffusion and in-situ oxidation treatments.The effects of different aluminizing time and thermal diffusion time on the coating thickness were studied.The oxidation resistance and compatibility of the aluminide coating with liquid lead were evaluated by static oxidation test and liquid lead corrosion test,respectively.The phase composition of the coating as well as the microstructure and element distribution of the coating before and after liquid lead corrosion were analyzed by XRD,SEM and EPMA.The aluminide coating prepared by pack cementation+thermal diffusion+in-situ oxidation is mainly composed of about 30μm FeAl phase layer and about 70μmα-Fe(Al)solid solution layer.In the process of heat treatment,the Fe-Al phase in the coating underwent the transformation of Fe₂Al₅,FeAl₂,FeAl,Fe₃Al andα-Fe(Al)in turn due to the phenomenon of mutual diffusion between Al and Fe.After static oxidation at 600℃ for 120 h,the oxidation weight gain of the aluminide coating is 0.028 mg/cm²,which is one order of magnitude lower than that of the CLAM steel.The aluminide coating changed the oxidation kinetic curve of CLAM steel from a linear law to a parabolic law.After corrosion of liquid lead at 550℃ for 600 h and 1800 h,the corrosion weight gain of aluminide coating were 0.058 mg/cm²and 0.077 mg/cm²respectively,which was only about 1/120 of the CLAM steel.A loose and porous iron oxide layer was formed on the surface of CLAM steel,and the aluminide coating did not corrode significantly,but after 1800 hours of corrosion,the thickness of the Al₂O₃ layer gradually decreased with the continuous consumption of the surface aluminum content.The aluminide coating has good oxidation resistance and compatibility with liquid lead,which can effectively inhibit the corrosion of liquid lead to CLAM steel.