Browsing by Author "Mawatari, T"

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EFFECTS OF SUBSTRATE SURFACE FINISH ON TRI- BOLOGICAL PERFORMANCE AND SURFACE TOPOGRA- PHY OF THERMALLY SPRAYED WC CERMET COATING
(Daffodil International University, 2008-07-01) Nuruzzaman, D. M.; Nakajima, A; Mawatari, T
In this study, tribological characteristics and surface topographies of thermally sprayed WC-Cr-Ni cermet coating were investigated experimentally under lubricated rolling with sliding contact conditions. Hi-HVOF sprayed WC cermet coatings were deposited onto the axially ground, blasted and circumferentially ground roller specimens made of an induction hardened carbon steel. It was found that under a contact pressure 1.4 GPa, cermet coating showed a high durability and life of the coating was not influenced by the substrate surface finish. It was also found that coefficient of friction and surface temperature were hardly affected by the substrate surface finish. On the other hand, after running, surface topographical parameters such as skewness, kurtosis and surface roughness were significantly influenced depending on the substrate surface finish. Namely, after the running-in process, the skewness in the case of circumferentially ground substrate became much more negative than that in the case of axially ground or blasted substrate. In addition, kurtosis and surface roughness of the coated surface were much more influenced in the case of circumferentially ground substrate than that in the case of axially ground or blasted substrate.
EXPERIMENTAL INVESTIGATION ON ROLING-SLIDING CONTACT PROPERTIES OF WC CERMET COATINGS
(Daffodil International University, 2009-01-01) Nuruzzaman, D. M.; Nakajima, A; Mawatari, T
In this study, tribological properties of Hi-HVOF sprayed WC-Cr-Ni cermet coatings were investigated experimentally under lubri-cated rolling-sliding contact. Coatings were deposited onto the induction hardened carbon steel and carburized hardened steel materials. Substrate surfaces were prepared by axially grinding, blasting and circumferentially grinding. Under the operating conditions of contact pres-sure PH=1.4 GPa and slip ratio s=-28.0%, the effects of substrate hardness and substrate sur-face kind on the tribological properties of the cermet coating were examined. It was found that cermet coating showed a long life and durability was not influenced by the substrate hardness and substrate surface kind. It was also found that during the running-in process, oil film formation was hardly influenced by the substrate hardness and substrate surface kind. On the other hand, surface hardness and surface roughness of the coating were more influenced in the case of circumferentially ground substrate than that in the case of axially ground or blasted substrate. In addition, coating material loss was very high in the case of circumferentially ground substrate when the substrate material was induction hardened carbon steel.