预氧化对一种镍基单晶高温合金的热腐蚀影响  

Effect of pre-oxidation on hot corrosion of a nickel-base superalloy

作　　者：王盼航 余竹焕[1] 张洋[1] 刘蓓蕾 WANG Panhang;YU Zhuhuan;ZHANG Yang;LIU Beilei(College of Material Science and Engineering,Xi'an University of Science and Technology,Xi'an 710054,China)

机构地区：[1]西安科技大学材料科学与工程学院,西安710054

出　　处：《材料科学与工艺》2018年第6期36-42,共7页Materials Science and Technology

基　　金：国家自然科学基金项目(51201130);陕西省教育厅专项科研计划项目(15JK1487)

摘　　要：为了解预氧化对镍基单晶高温合金的短时热腐蚀影响,采用涂盐法研究了一种高温合金经预氧化后在Na_2SO_4-NaCl盐膜条件下的热腐蚀行为,测量了不同预氧化处理时间合金的腐蚀动力学曲线,借助扫描电子显微镜(SEM)观察了合金腐蚀层截面的微观组织,并利用X-射线衍射仪(XRD)确定相结构.结果表明:未经过预氧化处理的合金表面腐蚀严重,热腐蚀增重质量最多达到0. 033 mg/cm^2,其腐蚀动力学曲线遵循抛物线规律,而经过预氧化处理后合金表面腐蚀明显改善;合金在900℃下的热腐蚀符合硫化氧化模型,腐蚀产物出现了分层结构;合金的主要腐蚀产物是Ni O、Al_2O_3以及少量NiCr_2O_4、TiO_2、Ni S_2等,其中Al_2O_3、TiO_2等氧化物位于氧化层最外层;预氧化生成的Al_2O_3层对高温合金在Na_2SO_4-NaCl盐膜下的短时热腐蚀有明显的保护作用,腐蚀层厚度从170μm降低至80μm.致密的氧化物保护层能够显著阻止硫元素的扩散,提高合金的耐热腐蚀性能.To understand the effect of pre-oxidation on short-term hot corrosion of nickel-based single crystal superalloys,salt corrosion method was used to study the hot corrosion behavior of a superalloy after preoxidation under Na2SO4-NaCl salt solution. The corrosion kinetics curves of different pre-oxidation treatment time of the alloy were measured,the microstructure of the cross-section of the alloy corrosion layer was observed with a scanning electron microscope( SEM),and the phase structure was confirmed by X-ray diffraction( XRD). The result showed that the alloy surface without pre-oxidation was severely corroded,hot corrosion weight gain reached the maximum mass 0. 033 mg/cm2,and the corrosion kinetic curve followed the parabolic law. After pre-oxidation treatment,the corrosion of the alloy surface was obviously improved,the hot corrosion of the alloy at 900 ℃ accorded with the model of sulfurization oxidation,and corrosion products appeared layered structure. The main corrosion products of the alloy were Ni O,Al2O3,a small amount of NiCr2O4,TiO2,NiS2,and so on,among which oxides such as Al2O3,TiO2 located on the outermost layer of the oxide layer. The pre-oxidized Al2O3 layer had a significant protective effect on short-term hot corrosion of superalloy under Na2SO4-NaCl salt film. The thickness of the etching layer was reduced from 170 μm to80 μm. A dense oxide layer could significantly prevent the diffusion of sulfur and improve the hot corrosion resistance of the tested alloy.

关 键 词：镍基高温合金 预氧化 热腐蚀 Na2SO4-NaCl 硫化氧化模型 

分 类 号：TG174.45[金属学及工艺—金属表面处理]