Potential use of additives to prevent corrosion in aero gas turbines

As an alternative to coatings, SiO₂-, alumina-, magnesia- and/or chromiaforming organometallic compounds were tested as additives in hot gas creep and thermal fatigue facilities with respect to their potential to reduce high temperature corrosion of the alloys IN 100, B 1914 and MAR M 002 under service conditions for aero engines. The creep lifetime of the alloys IN 100 and M 002 in hot gas with salt is increased by silicon additives, whereas under the same conditions this additive is detrimental to B 1914. The modified oxide scale formation was examined by scanning electron microscopy, Auger electron spectroscopy, energy-dispersive analysis of X-rays and X-ray diffraction. The mechanism of protection and the applicability for aero gas turbines are discussed.