Mechanical and thermal transport properties of suspension thermal sprayed Alumina-Zirconia composite coatings

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DOIResolve DOI: http://doi.org/10.1007/s11666-007-9146-0
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TypeArticle
Journal titleJournal of Thermal Spray Technology
Volume17
Issue1
Pages91104; # of pages: 14
Subjectabrasive and erosive wear; nanocrystalline composites; solution-precursor TS
AbstractMicro-laminates and nanocomposites of Al₂O₃ and ZrO₂ can potentially exhibit higher hardness and fracture toughness and lower thermal conductivity than alumina or zirconia alone. The potential of these improvements for abrasion protection and thermal barrier coatings is generating considerable interest in developing techniques for producing these functional coatings with optimized microstructures. Al₂O₃-ZrO₂ composite coatings were deposited by suspension thermal spraying (APS and HVOF) of submicron feedstock powders. The liquid carrier employed in this approach allows for controlled injection of much finer particles than in conventional thermal spraying, leading to unique and novel finescaled microstructures. The suspensions were injected internally using a Mettech Axial III plasma torch and a Sulzer-Metco DJ-2700 HVOF gun. The different spray processes induced a variety of structures ranging from finely segregated ceramic laminates to highly alloyed amorphous composites. Mechanisms leading to these structures are related to the feedstock size and in-flight particle states upon their impact. Mechanical and thermal transport properties of the coatings were compared. Compositionally segregated crystalline coatings, obtained by plasma spraying, showed the highest hardness of up to 1125 VHN₃ N, as well as the highest abrasion wear resistance (following ASTM G65). The HVOF coating exhibited the highest erosion wear resistance (following ASTM G75), which was related to the toughening effect of small dispersed zirconia particles in the alumina-zirconia-alloyed matrix. This microstructure also exhibited the lowest thermal diffusivity, which is explained by the amorphous phase content and limited particle bonding, generating local thermal resistances within the structure.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Industrial Materials Institute
Peer reviewedYes
NRC number48958
NPARC number15774998
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Record identifierc9206dc3-f6a9-4112-945c-32447816f8a6
Record created2010-07-06
Record modified2016-05-09
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