合金元素钨对新型Co-Al-W合金热腐蚀行为的影响

Effect of alloying element tungsten on hot corrosion behavior of novel Co-Al-W superalloys

研究Co-Al-W和商用MAN900合金在800℃75%Na2SO4+25%NaCl混合熔盐中的腐蚀动力学及热腐蚀行为。结果表明:7.5 W、9.8 W和10.7 W合金经热腐蚀后质量增加量比MAN900合金的质量增加量少,Co-Al-W合金的耐热腐蚀能力比MAN900合金的耐热腐蚀能力强。Co-Al-W合金在熔盐中腐蚀膜结构分成3层,即呈蓬松状由富钴氧化物Co3O4组成的腐蚀膜最外层,由Co、Al、W复杂氧化物组成的中间过渡层和主要由Al及Co氧化物组成较致密的腐蚀膜内层。随着腐蚀时间的增加,合金腐蚀膜最外层由于脱落逐渐变薄;中间过渡层厚度逐渐增加,该层中各元素分布趋于均匀、稳定;腐蚀膜内层致密性增加使该层增厚不明显。

The hot corrosion kinetics and hot corrosion behavior of Co-Al-W and MAN900 superalloys at 800 ℃ in 75%Na2SO4＋25%NaCl molten salt were studied.The results show that the mass gains of 7.5 W,9.8 W and 10.7 W alloys are less than those of MAN900 superalloy.The hot corrosion resistance of Co-Al-W superalloys is superior to that of MAN900 superalloys.The hot corrosion oxide scale of Co-Al-W superalloys is made up of three layers,that are,the external corrosion layer consisting of Co oxide（Co3O4）,the intermediate mixed oxides layer composed of complex oxide and nonuniform-barren oxide layer of Co,Al,W and an internal attacked layer with different compounds of Co,Al and O.With the increase of corrosion time,the intermediate mixed oxide layer becomes thicker,the external layer becomes thinner and internal layer almost has no change,but compactness of internal layer increases gradually.