Deposition and cyclic oxidation behavior of a protective (Mo,W)(Si,Ge) [sub 2] coating on Nb-base alloys

Journal Article · Fri May 01 04:00:00 EDT 1992 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2069395· OSTI ID:6918225

Mueller, A; Wang, G ^[1]; Rapp, R A ^[2]

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1. Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
2. 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), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 139:5; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360205 -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400 -- Electrochemistry
ALLOYS
CHEMICAL REACTIONS
COATINGS
CORROSION PROTECTION
DEPOSITION
DIFFUSION
DISPERSIONS
ELEMENTS
EXPANSION
FILMS
GERMANIUM ALLOYS
HEAT RESISTANT MATERIALS
MATERIALS
MATERIALS TESTING
METALS
MIXTURES
MOLYBDENUM COMPOUNDS
MOLYBDENUM SILICIDES
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
OXIDATION
PHYSICAL PROPERTIES
PROTECTIVE COATINGS
REFRACTORY METAL COMPOUNDS
REFRACTORY METALS
SILICIDES
SILICON ALLOYS
SILICON COMPOUNDS
SOLID SOLUTIONS
SOLUTIONS
SURFACE COATING
TESTING
THERMAL EXPANSION
THERMODYNAMIC PROPERTIES
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TUNGSTEN SILICIDES