The effects of sulfur and reactive elements to the microstructure of alumina scale on heat-resistant alloys

本研究的目的是阐明硫和活性元素对耐热合金中氧化铝垢微观结构的影响。研究了Fe-20Cr-4Al合金在1273、1373、1473、1573和1673K条件下，3、35、53、104、171、185、491、1300和6300ppmS的氧化行为。在任何氧化温度下，3ppmS上的氧化鳞都表现出良好的氧化粘附性。氧化鳞在35,53和104ppmS在1473K氧化后的冷却期间广泛剥落。在1473K.2氧化后，3ppmS上的氧化鳞呈平面状，而7,35和53ppmS上的氧化鳞呈卷曲状。研究了Fe-20Cr-4Al合金（185ppmS）和含钇（10、300、800和3700ppmY）、含铪（500、900、1900和4300ppmHf）合金在1273、1373、1473、1573和1673K氧中18ks的氧化行为。由于硫的去除和硫化钇颗粒的形成，钇掺杂合金表现出更好的氧化物粘附性。另一方面，在1573K.3氧化后，掺铪合金的氧化层剥落。研究了Fe-20Cr-4Al（3、7、53、104、171、185和1300ppmS、10、300、800和3700ppmY、500、900、1900和4300ppmHf）在1373、1473和1573K空气中360ks的氧化行为。1573K氧化后，7和53ppmS的氧化皮粘附良好，而104、171、185和1300ppmS的氧化皮在冷却过程中剥落。另一方面，掺钇合金表现出良好的氧化物粘附性，掺铪合金表面的氧化物鳞片剥落。氧化温度、氧化时间、硫、钇、铪的含量对合金表面氧化鳞的微观结构有影响。

The purpose of this study is to clarify the effect of sulfur and reactive elements to the microstructure of alumina scale on heat-resistant alloys.1. Oxidation behavior of Fe-20Cr-4Al alloys with 3, 35, 53, 104, 171, 185, 491, 1300 and 6300ppmS was studied for 18ks at 1273, 1373, 1473, 1573 and 1673K in oxygen. Oxide scales on 3ppmS showed good oxide adherence at any oxidation temperatures. Oxide scales on 35, 53, and 104ppmS spalled extensively during cooling after oxidation at 1473K.Oxide scales on 3ppmS showed a planar morphology, however, oxide scales on 7, 35 and 53ppmS showed a convoluted morphology after oxidation at 1473K.2. Oxidation behavior of Fe-20Cr-4Al alloys (185ppmS), and the alloys with yttrium (10, 300, 800 and 3700ppmY), or hafnium (500, 900, 1900 and 4300ppmHf) was studied for 18ks at 1273, 1373, 1473, 1573 and 1673K in oxygen. Yttrium-doped alloys showed an improved oxide adherence because of removal of sulfur and formation of yttrium-sulfide particles into the substrate. On the othe hand, oxide scales on hafnium-doped alloys spalled after oxidation at 1573K.3. Oxidation behavior of Fe-20Cr-4Al (3, 7, 53, 104, 171, 185 and 1300ppmS, 10, 300, 800 and 3700ppmY, 500, 900, 1900 and 4300ppmHf) was studied for 360ks at 1373, 1473 and 1573K in air. After oxidation at 1573K, oxide scales on 7 and 53ppmS showed good oxide adherence, however, oxide scales on 104, 171, 185 and 1300ppmS spalled during cooling. On the other hand, yttrium-doped alloys showed good oxide adherence, and oxide scales on hafnium-doped alloys spalled. The microstructure of oxide scales on the alloys depended on temperature and time of oxidation, and contents of sulfur, yttrium or hafnium.