Permanganate conversion coating on AZ31 magnesium alloys with enhanced corrosion resistance

Jian, Shun-Yi; Chu, Yu-Ren; Lin, Chao-Sung

doi:10.1016/j.corsci.2015.01.040

Cited by 110 publications

(27 citation statements)

References 41 publications

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“…Although chromate chemical conversion treatment has a high-performing corrosion resistance for magnesium alloys, hexavalent chromium (Cr 6+ ) has been gradually banned, since it is toxic and harmful for the environment; hence the development of new ways towards chromium-free chemical conversion treatments [20][21][22]. Chromium-free acid salt treatment includes: phosphate conversion coating [23,24], phosphate-permanganate conversion coating [25][26][27], stannate conversion coating [28,29], vanadate conversion coating [30,31], cerium conversion coating [32,33], lanthanide conversion coating [34], hydrotalcite surface coating, and so forth [35,36]. Hydrotalcite coating has attracted much attention, due to its unique intercalation structure and its environmentally friendly properties [37][38][39][40][41][42][43][44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

et al. 2019

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The formation process of LDHs (layered double hydroxides) coating on magnesium alloy by the CO2 pressurization method was studied. The micro-structure was observed by OM, SEM and GAXRD. The weighted gain curve, apparent activation energy, and CO2 solubility curve were all calculated by equations. The potentiodynamic polarization curve, hydrogen evolution data, and immersion were analyzed by an electrochemical method. The results show that the LDHs coating was formed layer-by-layer. The formation positions were initially on the α-Mg phase, and then on the β-Mg17Al12 phase. It was found to be the most compact after 30 min. The LDHs coating began to appear to have severe cracks and holes over time. The formation process of the LDHs coating can be divided into three stages: a rapid growth stage (0–10 min), slow growth stage (10–20 min), and periodic growth stage (30 min, 1 h). The apparent activation energies in each of the three stages are 21.78, 31.86 and 34.92 kJ mol−1, respectively. The LDHs coating has a compact micro-structure and better anti-corrosion at a pressure of 3 MPa, a temperature of 50 °C and a time of 30 min. The CO2 pressurization promotes a formation reaction rate and achieves a high formation efficiency and good formation stability under the condition of zero pollution.

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Section: Introductionmentioning

confidence: 99%

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

et al. 2019

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“…However, chromate is toxic to the environment and hazardous to human beings, leading to it being banned in recent years. Lately, focus has turned to conversion coating that contains no chromium [12,19,20], such as phosphate [21,22], phosphate-permanganate [23][24][25], stannate [26,27], vanadate [28,29], cerate [27,30], lanthanite [31], and LDHs surface coatings [32][33][34][35][36]. Of these, LDH surface coating, as an environmentally friendly coating, has attracted more attention as it brings no pollution to the environment.…”

Section: Introductionmentioning

confidence: 99%

Anticorrosion Performance of LDH Coating Prepared by CO₂ Pressurization Method

Jiang

Bateer

Liu

et al. 2018

International Journal of Corrosion

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Many surface treatment methods are used to improve the corrosion resistance of magnesium alloys. LDH (layered double hydroxides) conversion coatings are currently found in the most environmentally friendly and pollution-free coatings of magnesium alloy. In this study, the CO2 pressurization method was applied to the preparation of LDH coating on magnesium alloy for the first time. The effect of CO2 pressurization on the formation and corrosion resistance of LDH coating on AZ91D alloy was investigated. The hardness and adhesion were significantly higher on LDH coating in the case of CO2 pressurization than it is in atmospheric pressure. The surface and cross-sectional morphologies show that LDH coating is more compact in the case of CO2 pressurization than with atmospheric pressure. The results of the polarization curve, hydrogen evolution, and immersion tests indicate that the corrosion resistance of the LDH coating prepared by the CO2 pressurization method was significantly improved.

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“…Although there are claims in the literature that some composite precursor compounds such as Permanganate/Molybdate [6] conversion coating has superior corrosion resistance to chromate and Molybdate conversion coatings separately, its application in the high technical end of the metal finishing industry may yet be in its infancy. Other claimed success is the permanganate conversion coating developed on Magnesium alloy [7]. The coating which was developed from an acidic bath is termed to be nearly crack-free and its corrosion resistance was markedly better than the untreated alloy.…”

Section: Introductionmentioning

confidence: 99%

Development and performance of hybrid coatings on aluminium alloy

Oki

Adediran

Olayinka

et al. 2017

J. Electrochem. Sci. Eng.

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Permanganate conversion coating on AZ31 magnesium alloys with enhanced corrosion resistance

Cited by 110 publications

References 41 publications

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

Anticorrosion Performance of LDH Coating Prepared by CO₂ Pressurization Method

Development and performance of hybrid coatings on aluminium alloy

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Permanganate conversion coating on AZ31 magnesium alloys with enhanced corrosion resistance

Cited by 110 publications

References 41 publications

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

Anticorrosion Performance of LDH Coating Prepared by CO2 Pressurization Method

Development and performance of hybrid coatings on aluminium alloy

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Anticorrosion Performance of LDH Coating Prepared by CO₂ Pressurization Method