硫酸钙沉积导致铁基和镍基合金的热腐蚀

作者在几种铁基和镍基高温合金的试样上涂硫酸钙盐膜在1000℃及1150℃加热研究了硫酸钙对这些合金热腐蚀的影响。测定了这些合金的高温腐蚀动力学曲线。对腐蚀产物进行了 X 射线衍射、电子衍射、电子探针分析及金相检查。实验结果证明:由硫酸钙沉积导致的热腐蚀与合金成份有密切的关系。温度愈高,盐膜愈厚,腐蚀也愈严重。含钼又有足够铝含量以生成 Al_2O_3氧化皮的合金,由于 Al_2O_3被 MoO_3酸性熔融,与 CaSO_4反应可能生成液态的 CaMoO_4,会发生严重的腐蚀。合金的铬含量增高会提高抗 CaSO_4沉积腐蚀的能力,抗蚀性原来不好的合金渗铬后抗蚀性亦显著提高。

HOT CORROSION OF IRON-AND NICKEL-BASE SUPERALLOYS CAUSED BY DEPOSIT OF CALCIUM SULFATE

The effect of calcium sulfate deposit on hot corrosion of iron-and nickel base superalloys was studied by coating various alloy samples with salt films of calcium sulfate and heating them up to 1000 and 1150℃.Kinetics curves were run for the alloys under study.Corrosion products were analyzed by X- ray diffraction,electron diffraction and electron probe analyses as well as by metallographic techniques.Experimental results showed that hot corrosion caused by CaSO_4 is highly composition dependent.Corrosion becomes more severe with increasing temperature and larger amount of salt coating.Mo-con- taining alloys with enough Al to give protective films of Al_2O_3 show catas- traphic corrosion due probably to the formation of liquid calcium molybdate. Increasing the Cr of content of the alloy raises its hot corrosion resistance,as is also evidenced by enhanced corrosion resistance of the less resistant alloys with chromizing.The mechanism of corrosion caused by CaSO_4 deposit is proposed.