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Effect of Spraying Powders Size on the Microstructure, Bonding Strength, and Microhardness of MoSi2 Coating Prepared by Air Plasma Spraying
Ist Teil von
Journal of thermal spray technology, 2014-08, Vol.23 (6), p.934-939
Ort / Verlag
Boston: Springer US
Erscheinungsjahr
2014
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Molybdenum disilicide (MoSi
2
) coatings were deposited on carbon steel by air plasma spraying technology with different feedstock powder sizes (i.e., powder A: −15 + 2.5 μm, powder B: −30 + 15 μm, powder C: −54 + 30 μm, powder D: −74 + 54 μm and powder E: −106 + 74 μm). Phase composition and microstructure of coatings were characterized by x-ray diffraction (XRD) and scanning electron microscope. The bonding strength and microhardness of coatings were also evaluated. The XRD results show that there exists mutual transformation between T-MoSi
2
and H-MoSi
2
phase and part of Mo-rich phases are formed because of oxidization during the spraying process. With the increase of spraying powders size, the content of Mo-rich phases (Mo or Mo
5
Si
3
) and molybdenum oxide (MoO
3
) in coatings decreases, and that of disilicide-rich phase (MoSi
2
) in coatings increases. The oxidation degree of MoSi
2
particle gradually decreases during the spraying process with the increase of spraying powders size. The MoSi
2
is the main phase of the as-sprayed coatings when the spraying powders size is beyond 30 μm. With the increase of spraying powders size, the porosity of the as-sprayed coating increases, and the bonding strength of the coating gradually decreases. The hardness of coatings first increases and then decreases with the increase of spraying powders size.