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反应元素对耐热合金氧化铝氧化膜微观结构的影响。研究了含3，35，53,104,171,185,491,1300和6300ppmS的Fe-20Cr-4Al合金在1273，第1373,1473,1573和1673K氧气中18K的氧化行为。3ppmS上的氧化膜在任何氧化温度下都表现出良好的氧化附着力。35ppmS、53ppmS和104ppmS的氧化膜在1473K氧化后的冷却过程中大量剥落。3ppmS的氧化膜呈平面状，而7ppmS、35ppmS和53ppmS的氧化膜在1473K氧化后呈卷曲状。研究了Fe-20Cr-4Al合金(185ppmS)和含Y(10,300,800和3700ppmY)或含Hf(500,900,1900和4300ppmHf)的合金在1273，第1373,1473,1573和1673K氧气中18K的氧化行为。掺Y合金由于硫的脱除和Y-S颗粒的形成，改善了合金的氧化物附着力。另一方面，在1573K氧化后，掺入Hf的合金表面的氧化膜发生剥落。研究了Fe-20Cr-4Al合金(3、7、53、104、171、185和1300ppmS，10、300、800和3700ppmY，500、900、1900和4300ppmHf)在第1373、1473和1573K空气中360K的氧化行为。在1573K下氧化后，7ppmS和53ppmS上的氧化膜表现出良好的氧化附着力，而104,171,185和1300ppmS上的氧化膜在冷却过程中剥落。另一方面，掺Y合金表现出良好的氧化膜附着性，合金表面的氧化膜剥落。合金表面氧化膜的微观结构取决于氧化温度和时间，以及硫、Y或Hf的含量。

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.