Preparation and corrosion resistance of titanium–zirconium–cerium based conversion coating on 6061 aluminum alloy

2019 ◽  
Vol 71 (3) ◽  
pp. 419-429 ◽  
Author(s):  
Wen Zhan ◽  
Xuzheng Qian ◽  
Boyi Gui ◽  
Lian Liu ◽  
Xiaohui Liu ◽  
...  
2020 ◽  
Vol 67 (2) ◽  
pp. 205-213
Author(s):  
Xiaobo Wang ◽  
Wen Zhan ◽  
Boyi Gui

Purpose The purpose of this paper is to develop a chrome-free and phosphorus-free chemical conversion coating with good corrosion resistance, a novel chemical conversion coating was prepared by adding cerium nitrate hexahydrate and salicylic acid in the treatment solution containing titanium/zirconium ions on 6061 aluminum alloy. Design/methodology/approach Compared with the AA6061 aluminum alloy matrix, the self-corrosion potential of the conversion coating is significantly positively shifted, the self-corrosion current density is greatly reduced and its corrosion resistance is significantly improved. Morphology and composition of the conversion coatings were observed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The microdomain structure of conversion coatings at different formation stages was analyzed by electron probe microanalyzer. Findings An optimized preparation technique of titanium–zirconium chemical conversion coating for AA6061 aluminum alloy is obtained: H2TiF6 4 mL/L, H2ZrF6 0.4 mL/L, salicylic acid 0.35 g/L, Ce(NO3)3·6H2O 0.14 g/L, reaction temperature 30°C, reaction time 120 s and pH 4.0. Originality/value The coating forms on the Al(Fe)Si intermetallic compound, and Ce3+ is preferentially adsorbed on the intermetallic compound. The hydrolysis of Ce3+ causes the local pH of the solution to decrease, which promotes matrix dissolution and charge migration. As the microanode/microcathode reaction occurs, the local pH of the solution increases, and Al2O3/ZrO2/TiO2 begins to deposit on the surface of the metal substrate.


Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 397 ◽  
Author(s):  
Hehong Zhang ◽  
Xiaofeng Zhang ◽  
Xuhui Zhao ◽  
Yuming Tang ◽  
Yu Zuo

A chemical conversion coating on 5052 aluminum alloy was prepared by using K2ZrF6 and K2TiF6 as the main salts, KMnO4 as the oxidant and NaF as the accelerant. The surface morphology, structure and composition were analyzed by SEM, EDS, FT–IR and XPS. The corrosion resistance of the conversion coating was studied by salt water immersion and polarization curve analysis. The influence of fluorosilane (FAS-17) surface modification on its antifouling property was also discussed. The results showed that the prepared conversion coating mainly consisted of AlF3·3H2O, Al2O3, MnO2 and TiO2, and exhibited good corrosion resistance. Its corrosion potential in 3.5 wt % NaCl solution was positively shifted about 590 mV and the corrosion current density was dropped from 1.10 to 0.48 μA cm−2. By sealing treatment in NiF2 solution, its corrosion resistance was further improved yielding a corrosion current density drop of 0.04 μA cm−2. By fluorosilane (FAS-17) surface modification, the conversion coating became hydrophobic due to low-surface-energy groups such as CF2 and CF3, and the contact angle reached 136.8°. Moreover, by FAS-17 modification, the corrosion resistance was enhanced significantly and its corrosion rate decreased by about 25 times.


2014 ◽  
Vol 881-883 ◽  
pp. 1385-1390
Author(s):  
Xian Fang Yang ◽  
Tian Quan Liang ◽  
Wei Wei ◽  
Dong Hui Deng ◽  
Guang Qiao Xu ◽  
...  

Preparation and the characteristics of environment-friendly Ce-Ti-Mn conversion coating on aluminum alloy 6061 were investigated by XRD, FESEM, EDS, TEM and AFM in this paper. It is indicated that coating characteristics such as the surface morphologies, microstructure and corrosion resistance, are greatly influenced by the formation technology at room temperature. The constituents and their concentration, and pH value of the conversion solution have an important role on the feature of Ce-Ti-Mn conversion film, which will significantly influence on the continuity, compactness and the crystalline structure of particles of the film. The concentrations of the main salt K2TiF6and oxidizer KMnO4have significant effect on the characteristics of the conversion coating. The Ce-Ti-Mn film grows in a lamellar way, composing of oxide and/ or hydroxide phases of Ce, Ti and Mn, some of which are amorphous. The formation mechanism of the Ce-Ti-Mn conversion coating is discussed in detail.


Author(s):  
Xu zheng Qian ◽  
Wen Zhan ◽  
Jing jing Pan ◽  
Yi ting Liu ◽  
Feng Huang ◽  
...  

2020 ◽  
pp. 2050030
Author(s):  
YAO QU ◽  
CHAOLIN YANG ◽  
XIAOYUE JIN ◽  
JIANCHENG DU ◽  
WENBIN XUE

The structural and phase transformation of microarc oxidation (MAO) coatings on 6061 aluminum alloy at 300∘C/3[Formula: see text]MPa steam were evaluated. After 10 days steam corrosion, the weight loss of coated alloys with 15[Formula: see text][Formula: see text]m and 75[Formula: see text][Formula: see text]m thickness was only about 1/10 and 1/50 of weight gain of bare alloy, respectively. The [Formula: see text]-Al2O3 and [Formula: see text]-Al2O3 phases in the MAO coatings were stable at 300∘C/3[Formula: see text]MPa steam, but many fine needle-like or brick-like boehmite crystalline particles also appeared on coating surface. The boehmite had a large influence on the permittivity of coatings at low frequency. The MAO treatment on 6061 aluminum alloy improved its corrosion resistance at high-temperature and high-pressure steam.


RSC Advances ◽  
2015 ◽  
Vol 5 (98) ◽  
pp. 80129-80135 ◽  
Author(s):  
Yu-qing Wen ◽  
Hui-min Meng ◽  
Wei Shang

The model before (left) and after (right) the dynamics simulation. It can be deduced that the formation of the self-assembled membrane was mainly dependent on interaction between the silicon oxygen bond and the metal surface atom.


2012 ◽  
Vol 182-183 ◽  
pp. 241-244
Author(s):  
Cheng Bao Xia ◽  
Wen Jun Ge ◽  
Hou Chuan Yang

In order to improve the repairing quality of aircraft envelope of the aluminum alloy LY12, the cerium conversion coating technology was studied by using the surface modification technique. Principle experiment was on the basis of aviation repair technological requirement, refers to the related technique, through examination of corrosion resistance and wear resistance performance of cerium conversion coating, the principal composition of the formula for making cerium conversion coating:Ce(NO3)3 + KMnO4+ Ce-1 (chemical additive), In order to determine each composition of the formula and the technology parameters scientifically, L9(34) orthogonal testing method was adopted, and the formula of surface modification solution was optimized, the technological conditions for making cerium conversion coating on the surface of aircraft envelope were determined. Results of corrosion resistance and wear resistance of the cerium conversion coating on the surface of the aluminum alloy LY12 aircraft envelope obtained by the new technology showed: 1. On the given test conditions, the best content of each chemical composition in the formula of modification solution for making cerium conversion coating on the surface were: l.Ce(NO3)3:14g/L,KMnO4:1g/L,addictive Ce-1:0.3g/L;Main technology parameters were :pH=1.5~2.7;temperature:20°C;time:15~25 min.;2. Under the same test condition, the corrosion resistance of surface of the cerium conversion coating obtained in test modification solution was better than Alodine 1001 obtained from Bombardier Corporation of Canada, and can meet the repairing demands of Aircraft Envelope.


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