The Protection of Aluminides by Alloying with Molybdenum in High Chlorine Containing Atmospheres at 1,000°C

M.C. Galetz, B. Rammer, M. Schütze

Nickel aluminides are widely employed as coatings to enhance the oxidation resistance of alloys at high temperatures. However, some modern processes require the use of extremely high levels of chlorine in the process gas. This evokes a type of attack that no classical coating system can withstand. Nickel aluminide with molybdenum addition has been reported to be a potential candidate material before, but the corrosion mechanism of this system has not yet been investigated. To evaluate the influence of the molybdenum content on the corrosion behavior of NiAl, coupons were manufactured using an arc-melting process. The degradation mechanisms of these samples in synthetic air with 10 % chlorine gas at 1,000 °C are reported and discussed. It was found that molybdenum addition to NiAl changes the mechanisms of the attack and highly decelerates the corrosion rate under such demanding conditions.

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