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Qing Jiang - One of the best experts on this subject based on the ideXlab platform.
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study of the formation and growth of tannic acid based Conversion Coating on az91d magnesium alloy
Surface & Coatings Technology, 2009Co-Authors: Xiaoming Che, Jianshe Lia, Qing JiangAbstract:Abstract A tannic acid based Conversion Coating was formed on AZ91D magnesium alloy through a solution containing C76H52O46 (tannic acid), NH4VO3, K2ZrF6 and H3PO4. The growth process and corrosion resistance of the Conversion Coating were investigated by SEM, FESEM, XPS, IR, potentiodynamic polarization and EIS test. The results showed that the main components of the Coatings were penta-hydroxy benzamide–magnesium complex, Al2O3 and MgF2. Zr(HPO4)2·H2O(α-ZrP) was first formed in the time interval of 70 s–120 s, which acted as catalyst to activate the main reaction of gallic acid being oxidized into the penta-hydroxy benzamide–magnesium complex, as well as the formation of MgF2 and Al2O3, which took place in the time interval of 120 s to 600 s. The thickness of Coating treated for 300 s and 600 s was 1.1 μm and 1.6 μm, respectively. Polarization measurement and EIS test in 3 wt.% NaCl solution indicated that the Conversion Coating treated for about 300–600 s shows good corrosion resistance while an excess time treatment (720 s) induces the Coating surface coarse and uneven, leading to the reduction of corrosion resistance of the Conversion Coating.
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study of the formation and growth of tannic acid based Conversion Coating on az91d magnesium alloy
Surface & Coatings Technology, 2009Co-Authors: Xiao-ming Chen, Jianshe Lian, Guangyu Li, Qing JiangAbstract:Abstract A tannic acid based Conversion Coating was formed on AZ91D magnesium alloy through a solution containing C76H52O46 (tannic acid), NH4VO3, K2ZrF6 and H3PO4. The growth process and corrosion resistance of the Conversion Coating were investigated by SEM, FESEM, XPS, IR, potentiodynamic polarization and EIS test. The results showed that the main components of the Coatings were penta-hydroxy benzamide–magnesium complex, Al2O3 and MgF2. Zr(HPO4)2·H2O(α-ZrP) was first formed in the time interval of 70 s–120 s, which acted as catalyst to activate the main reaction of gallic acid being oxidized into the penta-hydroxy benzamide–magnesium complex, as well as the formation of MgF2 and Al2O3, which took place in the time interval of 120 s to 600 s. The thickness of Coating treated for 300 s and 600 s was 1.1 μm and 1.6 μm, respectively. Polarization measurement and EIS test in 3 wt.% NaCl solution indicated that the Conversion Coating treated for about 300–600 s shows good corrosion resistance while an excess time treatment (720 s) induces the Coating surface coarse and uneven, leading to the reduction of corrosion resistance of the Conversion Coating.
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An organic chromium-free Conversion Coating on AZ91D magnesium alloy
Applied Surface Science, 2008Co-Authors: Xiao-ming Chen, Jianshe Lian, Qing JiangAbstract:Abstract Traditional Conversion Coatings on magnesium alloys are usually immersed in a solution containing hexavalent chromium compounds. However, the replacement treatments have been proposed by the present environmental driving to eliminate hexavalent chromium. In this work, a tannic acid based Conversion Coating on AZ91D magnesium alloy was obtained by treatment in a solution containing tannic acid and ammonium metavanadate. SEM, XPS and IR were used to determine the morphology and structure of the Conversion Coatings. Continuous and uniform Conversion Coating was deposited on AZ91D alloy and the main components of the Coatings were Al 2 O 3 , MgF 2 and penta-hydroxy benzamide–magnesium complex. The formation mechanism of the Coating was discussed. Polarization measurement and salt spray test showed that the corrosion resistance of the Conversion Coating was much higher than that of traditional chromate Conversion Coating.
Songlin Mu - One of the best experts on this subject based on the ideXlab platform.
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investigation of composition and structure for a novel ti zr chemical Conversion Coating on 6063 aluminum alloy
Progress in Organic Coatings, 2015Co-Authors: Wen-fang Li, Songlin Mu, Yunyu Yang, Jun Du, Peng TangAbstract:Abstract A novel chemical Conversion Coating was prepared by adding tannic acid and Coating-forming accelerator in the treatment solution containing titanium and zirconium ions. Corrosion behavior of the Coatings in contact with 3.5% NaCl solution was investigated using potentiodynamic measurement. The structure and composition of the Coatings were determined with EDS, XPS and IR. The morphologies of the Coatings were observed with scanning electron microscopy (SEM). According to the results, the modified Ti–Zr based Conversion Coating (MTZ) shows a smoother and more compact morphology characterization comparing with the traditional Ti–Zr treated (TZ) substrates; The Tafel results and the long-time immersion experiments also indicate that the MTZ Coating presents a more effective corrosion protection property compared with the TZ Coating; The MTZ Coating is a multi-components chemical Conversion Coating which is mainly composed of metal oxide (TiO 2 , ZrO 2 , V 2 O 5 , Al 2 O 3 ), fluoride (AlF 3 and ZrF 4 ) and metal–organic complex.
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a vanadium based Conversion Coating as chromate replacement for electrogalvanized steel substrates
Journal of Alloys and Compounds, 2011Co-Authors: Ning Li, Deyu Li, Songlin MuAbstract:Abstract The vanadium Conversion Coating as chromate replacement was prepared on electrogalvanized steel (EG) plates previously treated in a solution mainly composed of vanadate. Corrosion behavior of these EG plates in contact with 3.5% NaCl solution was investigated using potentio-dynamic measurement and electrochemical impedance spectroscopy (EIS) measurement. The morphology and composition of the vanadium Conversion Coating were studied using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) in conjunction with argon-ion sputtering. According to the results, the V-treated EG plate shows the best corrosion protection property compared with the untreated and Cr-treated EG plates. The vanadium-rich Coating is composed of the closely packed particles. The Coating mainly consists of vanadium and oxygen, which mainly exist as V 2 O 5 , VO 2 , and its hydrates such as V 2 O 5 · n H 2 O, VO(OH) 2 .
Huang Weidong - One of the best experts on this subject based on the ideXlab platform.
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study on the corrosion resistance of phytic acid Conversion Coating for magnesium alloys
Surface & Coatings Technology, 2006Co-Authors: Liu Jianrui, Guo Yina, Huang WeidongAbstract:Abstract Chemical Conversion treatment is a basic method to improve the corrosion resistance of magnesium and its alloys. In the method of conventional Conversion, however, the solution contains hexavalent chromium compounds which are harmful to the environment. The replacement surface treatment has been strongly emphasized in recent years. A chemical Conversion treatment solution containing phytic was developed in this study for magnesium alloys. The surface Conversion Coating was characterized by SEM and EDS. The factors of influence to the corrosion resistance of Conversion Coating were discussed through hydrogen evolution method and polarization potential. The corrosion resistance of phytic acid Conversion Coating was comparable with the chromate containing. The experimental results indicate that the phytic acid Conversion Coating had better corrosion resistance when magnesium alloy was treated with a solution containing 0.5% to 1% phytic acid at temperature 25 to 60 °C and pH value at the range of 3∼5 for 30 to 60 min.
Peng Tang - One of the best experts on this subject based on the ideXlab platform.
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investigation of composition and structure for a novel ti zr chemical Conversion Coating on 6063 aluminum alloy
Progress in Organic Coatings, 2015Co-Authors: Wen-fang Li, Songlin Mu, Yunyu Yang, Jun Du, Peng TangAbstract:Abstract A novel chemical Conversion Coating was prepared by adding tannic acid and Coating-forming accelerator in the treatment solution containing titanium and zirconium ions. Corrosion behavior of the Coatings in contact with 3.5% NaCl solution was investigated using potentiodynamic measurement. The structure and composition of the Coatings were determined with EDS, XPS and IR. The morphologies of the Coatings were observed with scanning electron microscopy (SEM). According to the results, the modified Ti–Zr based Conversion Coating (MTZ) shows a smoother and more compact morphology characterization comparing with the traditional Ti–Zr treated (TZ) substrates; The Tafel results and the long-time immersion experiments also indicate that the MTZ Coating presents a more effective corrosion protection property compared with the TZ Coating; The MTZ Coating is a multi-components chemical Conversion Coating which is mainly composed of metal oxide (TiO 2 , ZrO 2 , V 2 O 5 , Al 2 O 3 ), fluoride (AlF 3 and ZrF 4 ) and metal–organic complex.
H Nakae - One of the best experts on this subject based on the ideXlab platform.
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a chromium free Conversion Coating of magnesium alloy by a phosphate permanganate solution
Surface & Coatings Technology, 2006Co-Authors: Ming Zhao, Shusen Wu, Y Fukuda, H NakaeAbstract:Abstract A chromium-free Conversion Coating for AZ91D magnesium alloy has been obtained by using a phosphate–permanganate solution, which has been developed out without acid pickling. Examinations have been carried out on the Conversion Coatings for morphology, composition, adhesion force, and corrosion resistance. Results show that the Conversion Coatings are relatively uniform and continuous, with thickness from 7 μm to 10 μm. They demonstrate good adhesion to matrix and have some non-penetrating tiny holes on the surface. The main elements of the Conversion Coating of AZ91D alloy are Mg, O, P, K, Al and Mn by EPMA analysis. Results of corrosion resistance test indicate that the corrosion resistance of the Conversion Coating by phosphate–permanganate solution is matched to that of the Conversion Coating by traditional chromate solution, but for the corrosion resistance after painting, the former is better than the later.
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A chromium-free Conversion Coating of magnesium alloy by a phosphate–permanganate solution
Surface & Coatings Technology, 2006Co-Authors: Ming Zhao, Ji Rong Luo, Y Fukuda, H NakaeAbstract:Abstract A chromium-free Conversion Coating for AZ91D magnesium alloy has been obtained by using a phosphate–permanganate solution, which has been developed out without acid pickling. Examinations have been carried out on the Conversion Coatings for morphology, composition, adhesion force, and corrosion resistance. Results show that the Conversion Coatings are relatively uniform and continuous, with thickness from 7 μm to 10 μm. They demonstrate good adhesion to matrix and have some non-penetrating tiny holes on the surface. The main elements of the Conversion Coating of AZ91D alloy are Mg, O, P, K, Al and Mn by EPMA analysis. Results of corrosion resistance test indicate that the corrosion resistance of the Conversion Coating by phosphate–permanganate solution is matched to that of the Conversion Coating by traditional chromate solution, but for the corrosion resistance after painting, the former is better than the later.