310不鏽鋼於850℃含一大氣壓SO2氣氛下的融鹽熱腐蝕行為

The Hot Corrosion Behaviour of SS310 at 850℃ under 1 atm SO2

本研究探討310不鏽鋼在850℃，（一大氣壓）二氧化硫的氣氛下，表面鍍Na2SO4及Na2SO4+NaCl對鋼材的熱腐蝕行為；研究顯示，僅含硫酸鈉的腐蝕性很小，但當硫酸鈉中添加少量的氯化鈉時，由於受到氯的影響，腐蝕速率會快速的增加。當氯化鈉含量達到100%時，對310不鏽的侵蝕行為極為嚴重，且其試片表面的氧化層可分為三層。最外層（第一層）為一較緻密的Fe3O4層，其中並分佈著FeS硫化物顆粒。中間層（第二層）為多孔性的Cr2O3層，也發現有Cr2S3硫化物。最內層（第三層）為一內硫化層，此層在高溫下為液態，並會沿著晶界上的孔洞向內部侵蝕，其成份會隨著侵蝕深度的不同而改變，由於此液態硫化層的關係，氧化層極易從硫化層/Cr2O3層的界面分離，而Fe3O4和Cr2O3之間的附著性相較之下較好。

The hot corrosion behavior of 310 stainless steel coated with NaSO4 and Na2SO4+NaCl was studied at 850℃ under 1 atm SO2. The results showed that little effect was observed by Na2SO4 coating, but addition NaSO4 with small amount of NaCl would increase the corrosion kinetics markedly. When the samples were coated with pure NaCl, the scale consisted of three layers. The outermost layer (layer 1) was Fe3O4 which contained FeS with dissolved Ni. The middle layer (layer 2) was Cro which contained Cr2S3 with dissolved Fe. The innermost layer (layer 3) was a liquid sulfide layer whose composition varied with the layer depth and grain boundary location. Because of the presence of liquid phase, the spallation was observed at the Cr2O3/layer 3 interface, while the adherence between Fe3O4/Cr2O3 was better.