High Temperature Corrosion Resistance of Pt-Based Superalloys in 0 . 2 % SO 2N 2 Gas
Pt-based superalloys are a new generation of materials intended to be used in various high temperature applications. Effluent gases emitted to the environment during combustion operations can lead to degradation of high temperature materials with deleterious effects on mechanical integrity and the corrosion of alloys. This paper focuses on sulphidation of one quaternary, and four ternary, Pt-based superalloys of various chemical compositions. Pt-based superalloys were exposed at 900°C in a reducing environment. The alloys were compared to coated and uncoated Ni-based superalloys (NBSAs). X-Ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman spectroscopy were used to characterize corrosion products that formed. The Pt-based superalloys exhibited higher corrosion resistance than NBSAs as a result of the formation of a protective Al2O3 scale, whereas NBSAs suffered internal sulphidation and formed Cr and Ni sulphide corrosion compounds. The formation of brittle needle-like phases and the transformation of the NiAl phase to Ni3Al, led to early failure of the coated alloy. Pt-based superalloys alloyed with Co showed poor corrosion resistance as a result of depletion of alloying elements.
PRACTICAL GUIDE TO HIGH-TEMPERATURE ALLOYS
The contents of this guide to high temperature alloys cover: the acceleration of corrosion by high temperatures; oxidation and scaling in high temperature processes; materials available for specific high temperature applications, including alloy steels, superalloys and metallic coatings; the comparative costs of the different materials; and special corrosion problems, among which are catastrophic oxidation, sulfidation, hot corrosion, deposits and fuel ash corrosion, carbonaceous environments, and halogen reactions.
Corrosion and its control : proceedings of International conference on Corrosion CORCON-97, Nehru Centre, Mumbai, India, 3-6 December 1997
Volume I. Part I - Plenary Talks. Corrosion control in nuclear power industry (Y.S.R. Prasad). High temperature corrosion problems in coal based power plants and possible solutions (J. Stringer). Corrosion performance of materials in coal-fired power plants (K. Natesan). Metallic materials for high temperature fuel cell application (W.J. Quadakkers et al.). Epoxy-coated reinforcing bars - an effective corrosion-protection system for reinforced concrete structures (D.P. Gustafson). Corrosion of reinforcement in concrete structures in India (S.A. Reddi). Corrosion distress in concrete - causes and protection (L.K. Aggarwal, S.C. Chakarbarti). Mechanisms of carburization and metal dusting methods of protection (H.J. Grabke). Waterwall corrosion in low-NOx combustion boilers (S. Kihara et al.). Biocorrosion in industrial applications (K.A. Natarajan). Recent developments in the use of non destructive testing techniques for monitoring industrial corrosion (B. Raj, T. Jayakumar). Prediction and assessment of corrosion in industrial operations (R.D. Kane et al.). Corrosion 'Health' monitoring systems for reduced maintenance/repair and increased system reliability (V.S. Agarwala). Life extension of plant components and damage assessment techniques (R. Viswanathan). Thermal barrier coatings for advanced gas turbines: Some materials, processing and evaluation related issues (S. V. Joshi). The design of sulphidation resistant materials: State-of-the-art and future prospects (P.K. Datta et al.). Advances in surface engineering (A.S. Khanna). II. Invited Talks. (23 papers). Volume II. Part III. Oral Papers. (50 papers). Part IV. Poster Papers. (55 papers). Author index.