Investigations into corrosion of aluminum coatings for compressor blades

The compressor blades of stationary gas turbines and jet engines are usually protected against corrosion by coatings. The coatings should delay the failure of the blades by corrosion fatigue. In compressor operation the coating systems are damaged by blasting wear (erosion). To insure a sufficient corrosion protection even by locally damaged coatings, coatings acting as sacrificial anode are preferentially applied. Inorganically bound aluminum coatings - consisting of aluminum pigments embedded in a matrix of chromate/phosphate compounds-have higher corrosion resistance than previously used compressor blade coatings (also under a simultaneous mechanical-dynamic stress). Therefore different inorganically bonded aluminum coatings were investigated and classified on their qualification as compressor blade coating. In this paper data are reported about basic corrosion tests (e.g. salt spray tests and alternating immersion tests) and about the electrochemical corrosion tests.