| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
The purpose of this study is to clarify the effects of water vapor on high-temperature oxidation of alumina-forming heat-resistant alloys with rare earths (Y, Lu) and noble metals (Pd, Pt, Au, Ir). Oxidation test was carried out at 1473, 1573 and 1673 K for 18 ks in O_2 (100cc/min) and in O_2-H_2O (dew point : 80℃) atmospheres.
1 Mass gain of all the alloys increased with increasing oxidation temperature of both oxidizing atmospheres.The addition of noble metals to the base alloy did not affect to the mass gain, however, the addition up to 0.1% of yttrium to the base alloy decreased the mass gain.
2 Alumina scale on the base alloy spalled at the entire surface after oxidation at 1473 and 1573 K both oxidizing atmospheres. Alumina scale on 0.5Pd alloy at 1573 K, and those on 0.5Au, 0.1Ir, 0.01Y and 0.1Y alloys at 1573 and 1673 K spalled for a large portion of the surface in an O_2-H_2O atmosphere, and amounts of oxide spalled of these alloys increased compared with these of the alloys obtained in an O_2 atmosphere.
3 Alumina scale on 0.5Y alloy showed good adherence both oxidizing atmospheres and at all the oxidation temperature in this study. This result suggested that 0.5Y alloy is one of promising water vapor resistant materials.
4 Oxide scale on 0.5Pt, 0.1Lu and 0.05Y alloys partially spalled in an O_2-H_2O atmosphere, however, the amount of spalled oxide of these alloys were small. Therefore, oxide adherence of these alloys was also improved compared with the base alloy.
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