The oxidation behavior of tungsten and germanium alloyed molybdenum disilicide coatings

Conference · Fri Nov 01 04:00:00 EST 1991

OSTI ID:6050424

Mueller, A; Wang, Ge; Rapp, R A ^[1]; Courtright, E L ^[2]; Kircher, T ^[3]

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1. Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
2. Pacific Northwest Lab., Richland, WA (United States)
3. 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: DOD; 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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
CHEMICAL REACTIONS
COATINGS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
DIFFUSION COATINGS
ELEMENTS
GERMANIUM
LAYERS
METALS
MICROSTRUCTURE
MOLYBDENUM COMPOUNDS
MOLYBDENUM SILICIDES
NIOBIUM
OXIDATION
REFRACTORY METAL COMPOUNDS
SCATTERING
SILICIDES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN
X-RAY DIFFRACTION