MECHANISM OF OXIDATION OF SOME NI-CR-BASED ALLOYS.
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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Conclusions 1 The rate of the oxidation of the binary alloy 80 Ni - 20 Cr is lower than the rate of oxidation of chromium at the temperature of 800 - 1000 C. The cause of the greater heat resistance of the alloy, as compared with chromium, is to be found in the formation on the surface of the alloy of an oxide film, the outside layer of which consists of NiCr204 and a higher energy of the transition of the ions of the chromium into the oxide film from the alloy, as compared with pure chromium. 2 The rate of the oxidation of the nichrome alloy falls with the addition of aluminum. The effect of the aluminum appears plainly with the temperature above 700 C. For successful protection of the alloy Ni-Cr from oxidation up to the temperature of 900 C, there is sufficient content of aluminum in the alloy of the amount of 4 to 5. For protection of the alloy at 1000 C, there is necessary the addition of aluminum to the amount of 7. Author
- Physical Chemistry
- Metallurgy and Metallography