Hot Corrosion and Oxidation Studies of Cobalt Based Superalloys at 1000 C.
Abstract
Recently, the trend in superalloy design has been aimed toward the development of alloys which are resistant to the harmful effects of sodium sulfate formed within gas turbines operated in marine environments. This phenomenon, commonly referred to as hot corrosion, has been extensively studied. These studies have elucidated the mechanism of sodium sulfate attack and have led to the development of alloys resistant to hot corrosion. One approach to the development of alloys resistant to hot corrosion involves the formation of a protective oxide layer based on SiO2. The feasibility of this approach has been verified. The data reported in this study agree well with those of other investigators and show a significant increase in the resistance of alloys to hot corrosive attack with increased silicon content of the alloys. Two rather limiting observations were made from this study. First, the scales forming on the high silicon containing alloys were very susceptible to spalling as a result of temperature changes. A means should be developed to increase the adherence of these scales onto the metal substrate. Secondly, the high silicon containing alloys were very brittle and probably could not withstand the mechanical stresses occurring within operating turbines. It would be more feasible for these alloys to be utilized as a surface coating on an alloy whose mechanical properties are more in accord with turbine material requirements. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 09, 1979
- Accession Number
- ADA080163
Entities
People
- Gregory A. Dries
Organizations
- Pennsylvania State University