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Open AccessFeature PaperArticle

Hot Corrosion Resistance of Laser-Sealed Thermal-Sprayed Cermet Coatings

1
LIMS, INSTM Reference Laboratory for Engineering of Surface Treatments, Department of Chemical Engineering Materials Environment, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
2
Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
*
Author to whom correspondence should be addressed.
Coatings 2019, 9(6), 347; https://doi.org/10.3390/coatings9060347
Received: 12 March 2019 / Revised: 24 May 2019 / Accepted: 25 May 2019 / Published: 28 May 2019
(This article belongs to the Special Issue Coatings for Harsh Environments)
Hot corrosion affects the components of diesel engines and gas turbines working at high temperatures, in the presence of low-melting salts and oxides, such as sodium sulfate and vanadium oxide. Thermal-sprayed coatings of nickel–chromium-based alloys reinforced with ceramic phases, can improve the hot corrosion and erosion resistance of exposed metals, and a sealing thermal, post-treatment can prove effective in reducing the permeability of aggressive species. In this study, the effect of purposely-optimized high-power diode laser reprocessing on the microstructure and type II hot corrosion resistance of cermet coatings of various compositions was investigated. Three different coatings were produced by high velocity oxy-fuel and was tested in the presence of a mixture of Na2SO4 and V2O5 at 700 °C, for up to 200 h: (i) Cr3C2–25% NiCr, (ii) Cr3C2–25% CoNiCrAlY, and (iii) mullite nano–silica–60% NiCr. Results evidenced that laser sealing was not effective in modifying the mechanism, on the basis of the hot corrosion degradation but could provide a substantial increase of the surface hardness and a significant decrease of the overall coating material consumption rate (coating recession), induced by the high temperature corrosive attack. View Full-Text
Keywords: type II hot corrosion; diode laser; sealing; thermal spray; HVOF; cermet type II hot corrosion; diode laser; sealing; thermal spray; HVOF; cermet
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MDPI and ACS Style

Baiamonte, L.; Bartuli, C.; Marra, F.; Gisario, A.; Pulci, G. Hot Corrosion Resistance of Laser-Sealed Thermal-Sprayed Cermet Coatings. Coatings 2019, 9, 347.

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