Ni基合金在900 ℃75%Na2SO4+25%NaCl盐膜下的热腐蚀

Hot Corrosion Behavior of Ni-Base Alloys Coated with Salt Film of 75%Na2SO4+25%NaCl at 900 ºC

摘要:

研究了纯Ni、Ni-10Cr和Ni-10Cr-5Al合金在900 ℃空气中涂敷Na2SO4+25%NaCl盐膜时的热腐蚀行为。结果表明，Ni-10Cr合金的腐蚀动力学曲线近似服从抛物线规律，而纯Ni和Ni-10Cr-5Al合金的腐蚀动力学曲线分段服从抛物线规律。Ni-10Cr的腐蚀增重最小，抗热腐蚀性能最好，Ni-10Cr-5Al次之，纯Ni的腐蚀增重最大。Ni-10Cr-5Al合金热腐蚀24 h后氧化产物分为3层，外层氧化产物主要是NiO，中间层氧化产物为Cr2O3和Al2O3，最内层有少量Cr2S3和Al2S3。Ni-10Cr合金热腐蚀24 h后氧化膜分为3层，外层氧化产物是NiO，中间层是不连续的Cr2O3，内腐蚀区有少量Cr2S3。由于熔盐中NaCl的存在，Ni-10Cr-5Al和Ni-10Cr合金的腐蚀产物会变得疏松多孔。

Abstract:

The hot corrosion behaviors of pure Ni, Ni-10Cr alloy and Ni-10Cr-5Al alloy (mass fractions, %, similarly hereinafter) coated with salt film of 75%Na2SO4+25%NaCl (mass fraction) were investigated at 900 °C in air. Results show that the corrosion kinetic curve of Ni-10Cr approximately follows the parabolic rate law while the corrosion kinetic curves of Ni and Ni-10Cr-5Al alloy follow the parabolic rate low by stages. The corrosion mass gain of Ni-10Cr is minimum, the one of Ni-10Cr-5Al comes next and that of pure Ni is maximum. The corrosion products of Ni-10Cr-5Al can be divided into three layers, of which the outermost layer is mainly composed of NiO, the intermediate layer consists of Cr2O3 and Al2O3 , and the internal corrosion zone contains a small amount of Cr2S3 and Al2S3. For Ni-10Cr alloy, the corrosion products consist of three layers, the outermost layer of NiO, the intermediate layer of noncontinuous Cr2O3 and the internal corrosion zone with a small amount of Cr2S3. The corrosion scales of Ni-10Cr-5Al and Ni-10Cr are both loose and porous due to the existence of NaCl.