Effects of Cr Element on Polarization Characteristic of Thermal Sprayed WC Cermet Coating.

Takatani, Yasuyuki; Tomita, Tsuneo; Tani, Kazumi; Inaba, Mitsuharu; Harada, Yoshio

doi:10.4139/sfj.49.396

Cited by 4 publications

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“…CoO dissolved to Co 2+ , which can be combined with water to form CoO again and also redeposited on the specimen surface. 6) However, these deposited oxides show no ability to reduce the corrosion rate, resulting in the rapid further dissolution of the sprayed composition. In fact, the island phenomenon appeared because of the rapid dissolving of Co. On the Cr-Coating specimen shown in Fig.…”

Section: Esca Surface Composition Analysis After Immersionmentioning

confidence: 99%

“…[1][2][3] However, their uses are limited by their poor corrosion resistance, though many efforts to improve WC-Co coatings [4][5][6][7] have been reported. In order to solve this problem, it is necessary to investigate their corrosion behaviors, 8) including passive film formation 9) in corrosive solutions, but to date, these have not been elucidated.…”

Section: Introductionmentioning

confidence: 99%

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Corrosion Behavior of Thermally Sprayed WC Coating in Na2SO4 Aqueous Solution

et al. 2002

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WC-Co thermally sprayed coating, formed by high velocity oxygen-fuel flame spraying, has had the problem of low corrosion resistance in aqueous solutions. Furthermore, much remains unknown regarding corrosion reactions on coating surfaces and the formation of passivation films. This study focused on changes of the corrosion surfaces of two thermally sprayed coatings, WC-12Co and WC-10Co-4Cr, with immersion time. The chemical composition of the corrosion surfaces was analyzed by electron spectroscopy, and the relation with passivation film stability is discussed. For WC-12Co, the thermally sprayed coating was immersed in Na 2 SO 4 solution. The W and Co components were dissolved by extended anodic reaction. Oxides of W and Co were then formed on the surface of the thermally sprayed coating. However, these oxides appeared to have little effect on the corrosion. Passivation film, which mainly consists of Cr 2 O 3 , was formed on the surface of WC-10Co-4Cr thermally sprayed coating immediately after immersion, and limited the dissolving of coating components into the aqueous solution. However, it is suspected that this film did not completely cover the entire coating surface. It is probably a thin porous film formed as islands.

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Section: Esca Surface Composition Analysis After Immersionmentioning

confidence: 99%