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:
- USDOD; Department of Defense, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6050424
- 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
- Country of Publication:
- United States
- Language:
- English
Similar Records
Deposition and cyclic oxidation behavior of a protective (Mo,W)(Si,Ge) [sub 2] coating on Nb-base alloys
PROTECTION OF MOLYBDENUM FROM OXIDATION BY MOLYBDENUM DISILICIDE BASED COATINGS
Related Subjects
MOLYBDENUM SILICIDES
OXIDATION
NIOBIUM
DIFFUSION COATINGS
GERMANIUM
LAYERS
MICROSTRUCTURE
TUNGSTEN
X-RAY DIFFRACTION
CHEMICAL REACTIONS
COATINGS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELEMENTS
METALS
MOLYBDENUM COMPOUNDS
REFRACTORY METAL COMPOUNDS
SCATTERING
SILICIDES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
360205* - Ceramics
Cermets
& Refractories- Corrosion & Erosion
360105 - Metals & Alloys- Corrosion & Erosion