A method for investigation of hot corrosion by gaseous Na sub(2)SO sub(4)

A novel in situ exposure method for investigating hot corrosion of aluminde coatings in the absence of an alkali sulphate melt is presented. The samples are exposed to Na sub(2)SO sub(4)(g) at a temperature above the dew point of the gas. Results from 100 and 500 h exposures at 900 degree C of Ni-based In792 covered with SIF232 aluminide coating are presented. Already after 100 h of testing, attack characteristic for Type I hot corrosion is observed. The reactions taking place during the testing are discussed and the results are compared with those from the well-known ex situ salt hot corrosion test.