INVESTIGATION INTO THE RESISTANCE OF VARIOUS NICKEL AND COBALT BASE ALLOYS TO SEA-SALT CORROSION AT ELEVATED TEMPERATURES
Abstract
Gas turbines operating in salt laden atmospheres occasionally encounter severe corrosion of the turbine blades. The cause of this attack is attributed to ingested sea-salt combining in the combustion chamber with the sulphur in the fuel to form sodium sulphate which is deposited on the turbine blades and leads to corrosive attack. Tests at 950 C indicated that Ni base alloys low in Cr were very susceptible to attack, but that a high Cr content alone was insufficient to ensure good corrosion resistance. However, the presence of adequate amounts of Al in the alloys appeared to be beneficial. The corrosion resistance of Co base alloys was no better than that of Ni-base alloys. A corrosion mechanism is proposed which involves the depletion of Cr from the surface of the alloy through sulphide formation so leading to a loosely-adherent Ni oxide film. Adequate percentages of Al in Ni does not form a stable sulphide and is therefore always available in the surface layers of the alloy to form protective aluminium oxide.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1965
- Accession Number
- AD0396420
Entities
People
- A. V. Dean