AISI 304表面硅化物渗层的制备及其900 ℃循环氧化性能研究
Preparation of Silicide Layer Deposited on AISI 304 Surface and Its Cyclic Oxidation Behavior at 900 ℃
安 亮1, 马 勤1,2, 贾建刚1,2, 李 鹏1
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作者单位：(1.兰州理工大学 甘肃省有色金属新材料省部共建国家重点实验室, 甘肃 兰州 730050; 2. 兰州理工大学 有色金属合金省部共建教育部重点实验室, 甘肃 兰州 730050)
中文关键字：Fe3Si； 硅化物渗层； 氧化膜； 氧化动力学； AISI 304
英文关键字：Fe3Si; silicide layer; oxide film; oxidation kinetic; AISI 304
中文摘要：采用NaCl ∶ KCl ∶ NaF=2 ∶ 2 ∶ 1(摩尔比)的中性熔融盐作为载体，Na2SiF6 ∶ Si=8 ∶ 2粉末做为渗硅剂，以SiO2为助渗剂，800 ℃下渗硅5 h可实现在AISI 304不锈钢表面形成厚约600 μm的富含Cr、Ni合金元素的Fe3Si型硅化物渗层，研究了渗层在900 ℃下的循环氧化行为。采用X射线衍射仪分析了渗层和氧化膜的物相组成，用附带能量色散谱仪附件的扫描电子显微镜研究了渗层和氧化膜截面的形貌和成分。结果表明，渗层为以Fe3Si相为主，Cr在渗层中含量低于其在304不锈钢基体中含量，而Fe和Ni在基体和渗层中的含量大致相当。氧化动力学遵从二次抛物线规律；Cr和Si元素发生上坡扩散形成以SiO2和Cr2O3为主的内层氧化膜，外层氧化膜以Fe2O3为主，这种复合氧化膜是渗层具有优异抗氧化性能的原因。
英文摘要：AISI 304 stainless steel was formed in molten salts at 800 ℃ for 5 h using molten mixture of Na2SiF6 ∶ Si=8 ∶ 2 as silionizing agent and the molten halogenide of alkali metals of NaCl ∶ KCl ∶ NaF=2 ∶ 2 ∶ 1 as siliconizing agent carrier by adding SiO2 as another source. The cyclic oxidation behavior of the layer at 900 ℃ was studied as well. The phase of the silicide layer and the oxide film was analyzed by X-ray diffraction. Meanwhile, the micrographs and the composition of the cross section of the silicide layer and the oxide film were studied by SEM and EDS. The results show that the phases of the silicide layer mainly consist of Fe3Si. The amount of Cr containing in silicide layer is lower than in AISI 304 matrix, while the amount of Fe and Ni containing in the layer is about equal to those in the matrix. The oxidation kinetic curve of the Fe3Si type silicide layer obeys a parabolic rule. The oxide film close to the interface of the oxide film/silicide layer contains with SiO2 and Cr2O3 resulting from the uphill diffusion of Cr and Si and the outer oxide film contains with Fe2O3. The composite oxide film accounts for the excellent high temperature oxidation properties.