کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1471277 | 1510042 | 2008 | 12 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Corrosion behaviour of cermet-based coatings with a bond coat in 0.5 M H2SO4 Corrosion behaviour of cermet-based coatings with a bond coat in 0.5 M H2SO4](/preview/png/1471277.png)
The corrosion behaviour of an HVOF Ni–5Al/WC–17Co coating on Al-7075 is investigated in 0.5 M H2SO4. In the temperature range of 25–45 °C, the coating exhibits pseudopassivity that effectively protects from localized corrosion. At 25 °C, pseudopassivity proceeds via three stages: during the first stage, oxidation of W in the binder phase occurs. The second stage is characterized by oxidation of W in both the binder and the carbide particles. The third stage is characterized by intensive hydration of WO3 and formation of Co3O4. During the second and third pseudopassive stages, the formation of a bi-layer surface film is postulated. The inner layer, consisting of anhydrous oxides, has a barrier character. The outer layer, composed of WO3 · xH2O, is unstable. In case of surface film disruption, the bond coat successfully hinders corrosion propagation into the Al-alloy. Higher electrolyte temperatures lead to faster corrosion kinetics and higher tendency for pitting.
Journal: Corrosion Science - Volume 50, Issue 12, December 2008, Pages 3389–3400