Optimisation of a salt deposition technique for the corrosion-fatigue testing of nickel based superalloys

ABSTRACT

This paper summarises the work undertaken to develop a salt deposition technique that can be utilised for hot corrosion and high temperature corrosion-fatigue testing of high performance alloys for gas turbine application. The optimisation process has yielded a new method of application of a sodium sulphate based solution to various test piece geometries. The technique employs the use of a micro-pipette to deposit a pre-calculated solution, consisting of methanol, water, Na₂SO₄–NaCl onto preheated specimens, in preparation for corrosion testing. This optimised salting technique has reduced the variability in the salting of test specimens, when compared with existing salt spray methods and has therefore enabled test repeatability along with an associated significant reduction in scatter within high temperature corrosion-fatigue results.

KEYWORDS:

• Superalloys
• molten salts
• corrosion-fatigue
• hot corrosion
• sulphidation
• high temperature corrosion
• test development