Coatings for Long Term-Intermediate Temperature Protection of Columbium Alloys
Abstract
The program objective was to develop protective coatings for columbium alloys that would provide hundreds of hours of protection at temperatures to 2500 deg F for application in gas turbine engines and aerospace environments. The coating systems under consideration were basically silicides and aluminides, with improvements to be achieved by modification with elements such as V, Al, Mo, Cr and Ti. Specifically, a ductile coating was sought that would improve upon the Cr-Ti-Si coating system, the standard of comparison for this program. The V-CrTi-Si system was extensively evaluated on various columbium alloy substrates. It exhibited a potential for 1000 hours of protection at 1000-3200 deg F in cyclic oxidation tests and over 200 hours at 2400 deg F. In oxidation-erosion rig tests the coating system protected various columbium alloy substrates for up to 200 hours at 2200 deg F and 100 hours at 2400 deg F. The V-CrTi-Si system was superior to the CrTi-Si system only in cyclic oxidation tests. In other tests, such as oxidation-erosion, ballistic impact, and slow thermal cyclic exposure, the two systems performed similarly.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1968
- Accession Number
- AD0843588
Entities
People
- J. D. Gadd
- J. F. Nejedlik