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2103 |
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Monday, May 03, 2010, Hullet Room 4:20 PM Off-Shore |
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Cavitation erosion characteristics and fracture morphology of thermal spray coating
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Akihiro Kanno* / TOCALO Co., Ltd., Japan Takeshi Takabatake/ Tocalo Co.,Ltd, Japan Yoshio Nanba/ Tocalo Co.,Ltd, Japan Kazumi Tani/ Tocalo Co.,Ltd, Japan Susumu Uematsu/ National Maritime Research Institute, Japan Shinobu Sugasawa/ National Maritime Research Institute, Japan Masaru Yoshioka/ Nakashima Propeller Co.,Ltd., Japan Yasuaki Ishihara/ Nakashima Propeller Co.,Ltd., Japan |
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The damage of the marine screw propeller parts caused by the cavitation erosion is one of the serious problems. Anti-erosive thermal spray coatings on the aluminium-bronze material are expected to extend the lifetime of propeller. In this study, Cobalt-based alloy, WC-cermet and Al2O3-ceramics coatings, which those test pieces were prepared using: (a) the atmospheric plasma spraying (APS), (b) the low-pressure plasma spraying (LPPS) and (c) the high-velocity oxygen-fuel (HVOF) spraying, were evaluated by the cavitation erosion test of the ultra-sonic vibration. The fracture morphology of cavitation erosion test pieces were analyzed by damaged surface observations and the erosion mass loss measurements. Cobalt-based alloy coatings produced by LPPS exhibited superior cavitation erosion resistance compared to APS coatings and HVOF coatings. This fact may be due to the dense structure of LPPS coatings. The cavitation erosion characteristics of Cobalt-based alloy coatings produced by HVOF were investigated in detail, because HVOF coatings can be capable of wide application compared to LPPS coatings for practical reasons.It is shown that the cavitation erosion resistance of coatings is associated with bonding strength of each deposited particles depending on their spray conditions. |