表面粉浴氧化鋁處理對鐵鋁基合金在含H2/H2S/H2O混合氣氛下之抗蝕效應研究

The Effect of Surface Alumina-packing Treatment on the Corrosion Resistance of Fe-Al Base Alloys in H2/H2S/H2O Mixed Gases

本研究主要探討鐵鋁基二元及三元合金（含Fe-28Al+5 at.% Cr、Mo及Y）經表面粉浴氧化鋁處理後在H2/H2S/H2O混合氣氛下，溫度範圍700～900℃間的高溫腐蝕行為。研究結果顯示，表面粉浴氧化鋁處理之各式合金在測試溫度範圍內的腐蝕動力學皆遵守拋物線型定律，且腐蝕速率隨溫度的增加而加快。由腐蝕動力學可知，經表面粉浴氧化鋁對合金抗蝕性有不同程度的改善，其中Fe-28Al-5Cr其腐蝕速率約可降低0.5～0.8個數量級；Fe-28Al-5Mo 其腐蝕速率約可降低0.2～0.3個數量級；Fe-28Al-5Y其腐蝕速率約可降低0.3～0.4個數量級，整體而言，Fe-28Al-5Y經氧化鋁處理後的腐蝕速率最低。經X-光繞射分析得知，粉浴處理之Fe-28Al-5Cr在700℃～900℃腐蝕時主要生成α-Al2O3，並伴隨Cr2S3、Fe1-xS，及少量的Al2S3；而粉浴處理之Fe -28Al-5Mo主要生成α-Al2O3，並伴隨MoS2及少量的FeS；而粉浴處理之Fe-28Al-5Y主要生成α-Al2O3及Y3Al5O12，並伴隨少量FeS。

The high-temperature corrosion of Fe-28Al and Fe-28Al-5M ternary alloys(where M= Cr, Mo, or Y) with the surface alumina-packing treatment has been studied over the temperature range 700~900℃ in H2/H2S/H2O mixed gases. The results indicated that the corrosion kinetics of all packing-treatment alloys followed the parabolic rate law, the corrosion rate constants increased with increasing temperature. Typical corrosion rates of Fe-28Al-5Cr with alumina-packing treatment are about 0.5~0.8 orders of magnitude lower than those of Fe-28Al-5Cr. In addition, the corrosion rate constants of Fe-28Al-5Mo and Fe-28Al-5Y with alumina-packing treatment can be reduced by 0.2~0.3 and 0.3~0.4 orders of magnitude, respectively, as compared to those without packing treatment. The adherence between the scales and the substrate, resulting in a significant reduction in the corrosion rates for Fe-28Al-5Y. XRD results showed that the scales formed on the Fe-28Al-5Cr with packing-treatment consisted of mostly Al2O3, and minor amounts of Cr2S3, Fe1-XS, and Al2S3. The scales formed on the Fe-28Al-5Mo with packing-treatment consisted of mostly Al2O3, some MoS2, and minor amount of FeS. The scales formed on the Fe-28Al-5Y with packing-treatment consisted of mostly Al2O3 and Y3Al5O12, and minor FeS.