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Influence of hardmetal feedstock powder on the sliding wear and impact resistance of High Velocity Air-Fuel (HVAF) sprayed coatings

Citace:
LYPHOUT, C. H., BOLELLI, G., KARHANOVÁ, E., SATO, K., YAMADA, J., HOUDKOVÁ ŠIMŮNKOVÁ, Š., LUSVARGHI, L., MANFREDINI, T. Influence of hardmetal feedstock powder on the sliding wear and impact resistance of High Velocity Air-Fuel (HVAF) sprayed coatings. WEAR, 2019, roč. 430, č. JUL 15 2019, s. 340-354. ISSN: 0043-1648
Druh: ČLÁNEK
Jazyk publikace: eng
Anglický název: Influence of hardmetal feedstock powder on the sliding wear and impact resistance of High Velocity Air-Fuel (HVAF) sprayed coatings
Rok vydání: 2019
Autoři: Christophe Lyphout , Giovanni Bolelli , Ing. Eva Karhanová , Kazuto Sato , Junya Yamada , Ing. Šárka Houdková Šimůnková Ph.D. , Luca Lusvarghi , Tiziano Manfredini
Abstrakt CZ: Práce je objasňuje, jak charakter WC-CoCr prášku, zejména velikost WC a matrice a pevnost jejich vzájemné vazby ovlivňuje kluzné třecí vlastnosti a odolnost proti cyklickému impaktnímu zatěžování povlaků deponovaných pomocí HVAF technologie.
Abstrakt EN: The present work aimed to clarify how the characteristics of WC-CoCr hardmetal feedstock powders, namely thegrain size of the WC carbides and of the binder and the compressive strength of the sintered aggregates, affect the dry sliding wear and impact resistance of coatings deposited by High Velocity Air-Fuel (HVAF) spraying. Ball-on-Disc tests, which mimic a sliding wear process in the presence of hard asperities as it may occur e.g. in hydraulic seal joints or papermaking components, resulted in mild wear through near-surface microscale plasticflow, the exact nature of which was significantly affected by WC size. Finite element simulations of a singleasperity sliding process indeed showed that large WC grains concentrate contact stresses, thus undergoing very localised deformation. It is experimentally seen that repeated deformation of the carbide grains resulted in their cracking and pull-out. Uniformly distributed, fine carbides allowed the matrix to take on some stress, thus undergoing more homogeneous plastic flow. Block-on-Ring tests elicited adhesive wear as it may happen e.g. in metal-to-metal contacts (e.g. petrochemical valves). This could be effectively restrained by low matrix mean free path. Cyclic impact resistance of coarse-grained coatings was better than that of fine-grained ones, because of better large-scale cohesive strength.
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