奥氏体不锈钢表面双辉等离子渗锆改性层的耐蚀性

Corrosion Resistance of Zr-Alloyed Layer on Austenite Stainless Steel by Double Glow Plasma Technique

利用双层辉光等离子渗金属技术,在0Cr18Ni9Ti奥氏体不锈钢表面形成了一层均匀致密连续的渗锆合金层,利用光学显微镜(OM)与扫描电子显微镜(SEM)分别观察了试样截面与表面的微观组织,并对其表面的物相进行了X射线衍射分析;且对不锈钢基材与渗锆合金层分别进行电化学腐蚀性能测试。结果表明:渗锆改性层的组织为柱状晶,渗锆改性层与基体有一明显分界线,且与基体呈良好的固态冶金扩散结合,渗锆改性层的物相主要为:ZrFe2,ZrC;在0.5 mol·L-1HCl溶液、3.5%NaCl溶液、0.5 mol·L-1NaOH溶液中,不锈钢基材的相对腐蚀速度分别是渗Zr合金层的24.43倍、2.44倍、1.90倍;未处理的不锈钢表面腐蚀较为严重,而渗Zr合金层表面只出现轻微的局部腐蚀,可见经渗锆处理后,不锈钢的耐蚀性有所提高。

A continuous and compact zirconium modified surface alloying layer was prepared on 0Cr18NigTi austenite stainless steel substrate by double-glow plasma surface alloying technology. The cross-section and surface microstructures of the samples were ob- served respectively by optical microscope（OM） and scanning electronic microscope （SEM）, and the phases of Zr-alloyed layer were analyzed by X-ray diffraction （XRD）. The electrochemical corrosion experiments were carried out for stainless steel and Zr-alloyed layer respectively. The results showed that the microstructure of Zr-alloyed layer was columnar crystal, and there was an obvious boundary between alloying layer and the matrix. Zr-alloyed layer achieved good solid metallurgical bonding with the matrix, and the phases of Zr- alloyed layer were mainly ZrFe2, ZrC. The relative corrosion rates of stainless steel were 24.43, 2.44 and 1.90 times of Zr-alloyed layer in 0.5 mol.L^-1 HCI solution, 3.5% NaC1 solution and 0.5 mol.L^-1 NaOH solution, respectively. The surface of unprocessed stainless steels were corroded seriously, but the surface of Zr-alloyed layers only existed slight local corrosion, which indicated that cor- rosion resistance could be improved after Zr-aUoyed layer being formed on 0Crl8NigTi stainless steel.