The oxidation behavior of tungsten and germanium alloyed molybdenum disilicide coatings
- Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
- Pacific Northwest Lab., Richland, WA (United States)
- Naval Air Development Center, Warminster, PA (United States). Aerospace Materials Div.
A two-step coating process was used to produce a (Mo,W)(Si,Ge){sub 2} coating on niobium. After exposure to high temperatures, a lower silicide layer forms underneath and is effective in arresting cracks. The oxidation weight-gain kinetics are parabolic following an initial transient period. Test coupons coated with (Mo,W)(Si,Ge){sub 2} passed 200 one-hour cycles at 1370{degree}C and 60 one-hour cycles at 1540{degree}C. These results, along with evidence of a thick protective glass layer, suggest that the germanium additions help cyclic oxidation resistance. The beneficial effects of the tungsten include the formation of microvoids, which provides a lower effective elastic modulus, and mechanical strengthening. No accelerated low temperature or ``pest`` oxidation was observed in the temperature range between 500--700{degree}C. Thus, a (Mo,W)(Si,Ge) multicomponent silicide coating offers significant promise for the protection of Nb-base alloys exposed to cyclic oxidizing environments over a broad range of temperatures.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (United States)
- Sponsoring Organization:
- Department of Defense, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 10122274
- Report Number(s):
- PNL-SA-20049; CONF-9111115-3; ON: DE92006509
- Resource Relation:
- Conference: High temperature structural silicides workshop,Gaithersburg, MD (United States),4-6 Nov 1991; Other Information: PBD: Nov 1991
- Country of Publication:
- United States
- Language:
- English
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