| WU Yong-zhong,REN Kun,XIE Ou,LU Jin-bing.Corrosion Behavior of Plasma Sprayed Aluminum Coating for X70 Pipeline Steel in Salt Spray Environment[J],48(5):85-89 |
| Corrosion Behavior of Plasma Sprayed Aluminum Coating for X70 Pipeline Steel in Salt Spray Environment |
| Received:November 14, 2018 Revised:May 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.05.013 |
| KeyWord:plasma spraying X70 pipeline steel aluminum coating pitting corrosion coating quality salt spray corrosion |
| Author | Institution |
| WU Yong-zhong |
Suzhou University of Science and Technology, Suzhou , China |
| REN Kun |
Suzhou University of Science and Technology, Suzhou , China |
| XIE Ou |
Suzhou University of Science and Technology, Suzhou , China |
| LU Jin-bing |
Suzhou University of Science and Technology, Suzhou , China |
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| Abstract: |
| X70 pipeline steel often fails due to corrosion during working. The work aims to study the anti-corrosion methods to extend the service life. Plasma sprayed aluminum coating was adopted to protect the substrate. The surface, interface quality and micro morphology of coating were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Salt spray corrosion test was used to compare coating protection mechanism. The results showed that the coating was aluminum-rich coating and mainly consisted of aluminum-rich brittle phase. Affected by air, the coating had some defects on surface like pores, micro-cracks and un-melted particles. The element aluminum was distributed in wave on the coating surface due to difference of melting degrees of particles in different sizes. The coating bonding strength was enhanced due to the Fe-Al metallurgical bonding caused by inter-infiltration between Fe and Al. After heat treatment, part of oxides and un-melted particles were fused by the heat and then flowed into the coating gaps, thus decreasing the coating porosity and reducing surface roughness, and enhancing the coating quality. The un-treated substrate surface showed serious pitting corrosion after 16 h of salt spray corrosion test, which affected the pipeline steel service life. There was only slight corrosion phenomenon on the coating surface after 120 h corrosion test. The oxidation film formed on the coating surface acts as a barrier between corrosion mediums and substrate, and enhances the anti-corrosion property of X70 pipeline steel. |
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