Accession Number : AD0901571

Title :   Investigation of Corrosion-Resistant Coatings for Service at 2500 F.

Descriptive Note : Final engineering rept. 9 Jun 71-8 May 72,

Corporate Author : BATTELLE COLUMBUS DIV OH

Personal Author(s) : Bartlett, E. S. ; Browning, M. F. ; Bower, W. K. ; Felton, G. W. ; Stowell, W. R.

Report Date : 05 JUL 1972

Pagination or Media Count : 149

Abstract : A materials concept that holds promise for providing safe, reliable operation of advanced jet engines using coated columbium alloys in critical turbine components was explored. The key to this concept is a semioxidation resistant, metallic alloy layer positioned between the primary protective silicide coating and the structural columbium alloy substrate. In addition to providing 'back-up' oxidation resistance at defects in the primary coating, this barrier layer 'getters' oxygen and prevents contamination embrittlement of the underlying load-bearing substrate. One model system was evaluated sufficiently to show the feasibility of the basic concept. Provision of the 'second-line-of-defense' against oxidation-contamination in the model system completely protected the structural columbium alloy substrate against degradation in all tests. Reference standards of a state-of-the-art columbium alloy system were degraded by contamination in all tests. The kinetics describing the behavior of the model system suggested that useful lifetime, even in the event of outer coating failure, will be sufficient to permit the reliable use of the model system in advanced gas turbine engines.

Descriptors :   *CORROSION INHIBITION), (*BARRIER COATINGS, (*TURBOJET ENGINES, COATINGS), (*NIOBIUM ALLOYS, COATINGS), (*GAS TURBINE BLADES, METAL COATINGS), TURBINE BLADES, SUBSTRATES, SILICIDES, DIFFUSION COATING, OXIDATION, SULFATES, EMBRITTLEMENT, FAILURE(MECHANICS), TITANIUM ALLOYS, HAFNIUM ALLOYS, DEGASIFICATION, HARDNESS, RELIABILITY, MICROSTRUCTURE, HIGH TEMPERATURE, SILICON COATINGS, SILICON COMPOUNDS, NITRIDES, SODIUM COMPOUNDS, TANTALUM ALLOYS, CRACKS, SODIUM CHLORIDE, METALLOGRAPHY.

Subject Categories : Coatings, Colorants and Finishes
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE