Oxidation and Hot Corrosion of Superalloys Rene 100 and X-40 at Temperatures of 1475 F to 2000 F
ARMY RESEARCH LAB WATERTOWN MA MATERIALS DIRECTORATE
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The oxidation resistance and hot corrosion resistance of two superalloys, Rene 100 and X-40, and an aluminide coating for the protection of one of the superalloys are compared. The comparison is made by using tube- furnace oxidation and hot corrosion tests employing a Mettler TGA apparatus at temperatures of 1475 deg F to 2200 deg F. For hot corrosion tests the samples were precoated with Na2SO4 prior to heating to the desired temperature and introducing air at a flow rate of 57 cmmin. The oxidation behavior to Rene 100 was poor compared to that-of the X-40 alloy, especially at temperatures above 1900 deg F. The X-40 alloy was found to be more resistant to the initiation of hot corrosion than Rene 100. Both alloys, however, undergo attack at rates consistent with an alloy-induced fluxing mechanism. An aluminide coating on Rene 100 caused the initiation of hot corrosion to be delayed. Attack did occur when cumulative applications of Na2SO4 were used. The coatings were penetrated by the Na2SO4 in localized areas after exposure times of less than 200 hours. The hot corrosion test has validity for mechanisms whereby the degradation process is sustained by reaction products from the alloy. It, therefore, can be used to compare the time to establish such conditions in alloys. Rene 100 is more susceptible to this condition than X-40.... Superalloys, Nickel-base superalloys, Cobalt-base superalloys Oxidation resistance, Corrosion, Sulfidation, Aluminide Coatings.
- Physical Chemistry
- Coatings, Colorants and Finishes
- Properties of Metals and Alloys