Deposition and cyclic oxidation behavior of a protective (Mo,W)(Si,Ge) [sub 2] coating on Nb-base alloys
- Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
- Battelle Pacific Northwest Lab., Richland, WA (United States)
A multicomponent diffusion coating has been developed to protect Nb-base alloys from high-temperature environmental attach. A solid solution of molybdenum and tungsten disilicide (Mo, W)Si[sub 2], constituted the primary coating layer which supported a slow-growing protective silica scale in service. Germanium additions were made during the coating process to improve the cyclic oxidation resistance by increasing the thermal expansion coefficient of the vitreous silica film formed and to avoid pesting by decreasing the viscosity of the protective film. In this paper, the development of the halide-activated pack cementation coating process to produce this (Mo,W)(Si,Ge)[sub 2] coating on Nb-base alloys is described. The results of cyclic oxidation for coupons coated under different conditions in air at 1370[degrees]C are presented. Many coupons have successfully passed 200 1 h cyclic oxidation tests at 1370[degrees]C with weight-gain values in the range of 1.2 to 1.6 mg/cm[sup 2].
- OSTI ID:
- 6918225
- Journal Information:
- Journal of the Electrochemical Society; (United States), Vol. 139:5; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GERMANIUM ALLOYS
OXIDATION
PROTECTIVE COATINGS
MOLYBDENUM SILICIDES
NIOBIUM BASE ALLOYS
CORROSION PROTECTION
SURFACE COATING
SILICON ALLOYS
TUNGSTEN SILICIDES
DIFFUSION
HEAT RESISTANT MATERIALS
MATERIALS TESTING
REFRACTORY METALS
SOLID SOLUTIONS
THERMAL EXPANSION
THERMODYNAMIC PROPERTIES
THIN FILMS
ALLOYS
CHEMICAL REACTIONS
COATINGS
DEPOSITION
DISPERSIONS
ELEMENTS
EXPANSION
FILMS
MATERIALS
METALS
MIXTURES
MOLYBDENUM COMPOUNDS
NIOBIUM ALLOYS
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
SILICIDES
SILICON COMPOUNDS
SOLUTIONS
TESTING
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
360105* - Metals & Alloys- Corrosion & Erosion
360205 - Ceramics
Cermets
& Refractories- Corrosion & Erosion
400400 - Electrochemistry
360204 - Ceramics
Cermets
& Refractories- Physical Properties