Characterization of oxidation and corrosion of VPS covers
The useful operating life of superalloy components operating in gas turbines is dependent to a large extent on the ability of applied surface coatings to resist corrosive degradation. Coatings have been fine tuned over many years of use to give satisfactory performance in airborne applications, but the recent adoption of gas turbines in the utility sector has placed renewed demand on the need to evaluate and develop existing and new coating systems. This paper describes the behaviour of a series of vacuum plasma sprayed MCrAlY(Si) and Al/Si coatings applied to the Ni-base IN738 and UD520 and Co-base FSX-414 and X45 superalloys. Test specimens have been exposed to both simple argon O(2)SO(2) gas mixtures and to simulated combustion gas mixtures in a low-velocity burner rig for times up to 1000 hours in the temperature range 800 C to 1000 C. The results obtained in the form of microstructural changes suggest an upper temperature limit below 900 C for the application of high Al and Si containing coatings due to interdiffusion with the base alloy and a strong influence of combustion gas composition on corrosion rate.
Bibliographic Reference: Paper presented: Giornata di Studio "Materiali per turbine a gas industriali", Milano (IT), April 23, 1996
Availability: Available from (1) as Paper EN 39693 ORA
Record Number: 199610625 / Last updated on: 1996-06-10
Original language: it
Available languages: it