耐熱鋼の高温酸化に關する研究 (I) : バナジウム腐蝕に關する研究
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Burning of heavy oil in gas turbines raises some special problems. Especially, "vanadium attack" is a problem of importance. This report discussed the fundamental experiment concerning vanadium attack and some methods which were being considered for preventing them. The presence of a small quantity of the vanadium pentoxide or artifical ash, 2mg (5mg) on specimens (15×20×1mm), was sufficient to increase the loss of metal from tenfold to fiftyfold in 100 hours. It was found that this attack was acceralated with increasing quantity of vanadium pentoxide or artifical ash. Especially, Timken 16-25-6 alloy was attached at 800∿850℃ very severely. It was presumed that when this alloy with 6 pct. molybdenum content was oxidized, molybdenum trioxide appeared on its surface, and because molybdenum trioxide as well as vanadium pentoxide which had the very low melting point, fused together with the oxide film, the protecting action of the film was destroyed. In addition, molybdenum trioxide and vanadium pentoxide were the catalyser of oxidizing reactions, and thus the oxidation of the alloy was remarkably promoted. The protection of vanadium attack would be needed either to render V_2O_5 inert (CaO, MgO etc.) or to provide some new kind of protective layer (ceramic coating etc.) over the materials. It was found that when vanadium pentoxide was mixed with MgO or CaO, the oxidizing reaction of materials was impeded at about 700℃∿800℃, and the materials which had been given ceramic coating showed very excellent results for vanadium attack at 800℃∿900℃.
- 1954-01-25
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