Synthesis and Characterization of Chrom-Free Dark Coating on AA6063 Aluminium Alloy with K2ZrF6

2014 ◽  
Vol 1053 ◽  
pp. 421-428
Author(s):  
Ting Yi Chen ◽  
Ye Qi Fu ◽  
Wen Lu ◽  
Wen Fang Li
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Corrosion Current ◽  
Visual Assessment ◽  
Electrochemical Analysis ◽  
Conversion Coating ◽  
Electrochemical Tests ◽  
Excellent Corrosion Resistance ◽  
New Treatment

A new passivation process has been developed for producing a chrome-free and coloured conversion coating on aluminium alloy AA6063 with K2ZrF6. The conversion coating obtained has a dark film, which enables visual assessment of the coating development and coating quality during processing. The colouring effect is a significant advantage over the zirconium based conversion coatings currently used in the industry, which are largely colourless. The new treatment process is simple and allows a uniform coating to be formed within a few minutes. The composition and the surface morphology of the coatings were characterized. The corrosion resistance of the coated samples was evaluated by electrochemical tests. Through electrochemical analysis, corrosion current of the coatings is low, it has excellent corrosion resistance; SEM, EDS and XRD are used to analyze the process coating.

Synthesis and Characterization of Chrom-Free Zr-Ti-Ni Pale Green Coating on AA6063 Aluminium Alloy

2014 ◽  
Vol 1053 ◽  
pp. 414-420
Author(s):  
Ting Yi Chen ◽  
Wen Lu ◽  
Ye Qi Fu ◽  
Wen Fang Li
Keyword(s):  
Room Temperature ◽  
Layer Structure ◽  
Corrosion Current ◽  
Xrd Analysis ◽  
Conversion Coating ◽  
Synthesis And Characterization ◽  
Electrochemical Tests ◽  
Film Forming ◽  
Pale Green

With K2ZrF6as the main film-forming material, Ni2SO4• 6 H2O as colorants, K2TiF6for coloring promoters, chrome-free conversion and treatment for Al6063 at room temperature has been developed, fluid can be of steady function without adding oxidants additionally, fast film forming within 6 minutes. By adding Ni element to make the conversion coating changed from gray to pale green, K2TiF6can promote color and uniform color. Analyzed sample through SEM observation, XPS and XRD analysis, the passivation was composed of Al, Ni, NiZr, Ti and NiZr3; By electrochemical tests, the corrosion current decreased to 0.067μA of passivation membrane, corrosion resistance increased nearly one hundred times, membrane layer structure circuit is C1 / R1 / (L2 + R2)/(L3 + R3)/(L4 + R4).

Corrosion Behavior and Microstructure of Pd Ions Doped Cerium Conversion Coating on AA2219-T87 Aluminum Alloy

2015 ◽  
Vol 1090 ◽  
pp. 79-83
Author(s):  
Yan Hong He ◽  
Zhen Duo Cui ◽  
Xian Jin Yang ◽  
Sheng Li Zhu ◽  
Zhao Yang Li ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Corrosion Behavior ◽  
Photoelectron Spectroscopy ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Conversion Coating ◽  
X Ray Diffraction ◽  
X Ray ◽  
Excellent Corrosion Resistance

In this paper, Pd ions doped cerium conversion coating (CeCC/Pd) was deposited on AA2219-T87 aluminum alloy by electroplating. The microstructure and composition of the coating were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS). Corrosion behavior of AA2219-T87 aluminum alloy with the coating was investigated in 3.5wt.% NaCl solution at the room temperature. XRD and XPS results indicate the existence of cerium-oxide and palladium-oxide in the CeCC/Pd. Polarization curves show that the CeCC/Pd exhibits excellent corrosion resistance. The corrosion current density of the CeCC/Pd decreases by two orders of magnitude compared with the CeCC. The improvement of corrosion resistance would be attributed to the small grain size, good compactness and adhesive strength of the composite coatings.

Study on corrosion resistance behavior and formation mechanism of Ce conversion coating on manganese

2021 ◽  
Vol 118 (3) ◽  
pp. 319
Author(s):  
Sihua Lei ◽  
Fei Lu ◽  
Shuai Wang ◽  
Hong Zhong ◽  
Zhanfang Cao ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Formation Mechanism ◽  
Electrochemical Impedance ◽  
Conversion Coating ◽  
Alkali Resistance ◽  
Conversion Coatings ◽  
Environmental Friendliness ◽  
Electrochemical Tests ◽  
Excellent Corrosion Resistance ◽  
Acid And Alkali Resistance

Ce conversion coatings have received extensive attention from researchers due to their excellent corrosion resistance and environmental friendliness. Here, Ce conversion coatings on manganese were prepared by treating in the cerium nitrate conversion solution. The influence of treating parameters was studied and optimized. The surface morphology, element composition and chemical state of Ce conversion coatings were studied by means of SEM, EDS, XRD and XPS. Electrochemical methods of polarization curve and electrochemical impedance were used to study the corrosion resistance of conversion coatings. The results showed that the Ce conversion coating contained mainly Mn, O and Ce, and its forms were manganese oxide and cerium oxide. Electrochemical tests showed that Ce conversion coating can not only effectively improve the corrosion resistance of manganese substrate, but also has good acid and alkali resistance. Discussion on the formation mechanism of cerium conversion coating shows that the conversion treatment is beneficial to inhibit the further oxidation of manganese to the higher valence state.

scholarly journals Glass-Forming Ability and Corrosion Resistance of Al88Y8−xFe4+x (x = 0, 1, 2 at.%) Alloys

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1581
Author(s):  
Rafał Babilas ◽  
Monika Spilka ◽  
Katarzyna Młynarek ◽  
Wojciech Łoński ◽  
Dariusz Łukowiec ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Analytical Techniques ◽  
Corrosion Current ◽  
Glass Forming Ability ◽  
Electrochemical Tests ◽  
Glass Forming ◽  
Transmission Electron ◽  
Composition And Structure ◽  
Amorphous Structures ◽  
The Impact

The effect of iron and yttrium additions on glass forming ability and corrosion resistance of Al88Y8-xFe4+x (x = 0, 1, 2 at.%) alloys in the form of ingots and melt-spun ribbons was investigated. The crystalline multiphase structure of ingots and amorphous-crystalline structure of ribbons were examined by a number of analytical techniques including X-ray diffraction, Mössbauer spectroscopy, and transmission electron microscopy. It was confirmed that the higher Fe additions contributed to formation of amorphous structures. The impact of chemical composition and structure of alloys on their corrosion resistance was characterized by electrochemical tests in 3.5% NaCl solution at 25 °C. The identification of the mechanism of chemical reactions taking place during polarization test along with the morphology and internal structure of the surface oxide films generated was performed. It was revealed that the best corrosion resistance was achieved for the Al88Y7Fe5 alloy in the form of ribbon, which exhibited the lowest corrosion current density (jcorr = 0.09 μA/cm2) and the highest polarization resistance (Rp = 96.7 kΩ∙cm2).

scholarly journals Preparation of Ti–Zr-Based Conversion Coating on 5052 Aluminum Alloy, and Its Corrosion Resistance and Antifouling Performance

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 397 ◽  
Author(s):  
Hehong Zhang ◽  
Xiaofeng Zhang ◽  
Xuhui Zhao ◽  
Yuming Tang ◽  
Yu Zuo
Keyword(s):  
Corrosion Resistance ◽  
Surface Modification ◽  
Aluminum Alloy ◽  
Current Density ◽  
Corrosion Current Density ◽  
Salt Water ◽  
Water Immersion ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Conversion Coating

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.

Electroless Multilayer Coatings Used in the Protection of Thermosyphon Economizer from Corrosion

2012 ◽  
Vol 512-515 ◽  
pp. 1607-1610
Author(s):  
Yang Xu ◽  
Yong Zou ◽  
Tao Luan
Keyword(s):  
Corrosion Resistance ◽  
Single Layer ◽  
Electroless Nickel ◽  
Corrosion Current ◽  
Multilayer Coatings ◽  
Electrochemical Tests ◽  
Exhaust Temperature ◽  
Electroless Copper ◽  
Save Energy ◽  
Better Than

Economizers are widely employed in the boiler system to increase efficiency and save energy. However one prominent problem is the severe corrosion of economizer due to the decrease of the exhaust temperature of boiler. Ni–P/Cu/Ni-P multilayer coatings, which could effectively improve the corrosion resistance of the facilities in economizer, are introduced in the present work. The three-layer coatings, whose composition is Ni–P/Cu/Ni-P from substrate to surface, were prepared using dual baths (acidic hypophosphite-reduced electroless nickel bath and acidic replacement electroless copper bath). The corrosion resistance of the coatings was evaluated by porosity and electrochemical tests. The results of porosity evaluation show that all the multilayer coatings performed better than the single-layer coatings of similar thickness. Similarly, The electrochemical tests showed lower corrosion current density for the multilayer coatings in 3.5 wt.% NaCl aqueous solutions.

Study on Properties of Zn-Al-Mg-RE Coatings by Arc Spraying

2013 ◽  
Vol 804 ◽  
pp. 79-84
Author(s):  
Fei Lu ◽  
Zhao Qian Xie ◽  
Yu Feng Lu ◽  
Miao Lou ◽  
Meng Zhou ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Arc Spraying ◽  
Long Term Effects ◽  
Electrochemical Protection ◽  
X Ray ◽  
Electrochemical Tests ◽  
Excellent Corrosion Resistance ◽  
Corrosion Reaction ◽  
High Velocity Arc Spraying

In order to improve the organization, reduce the porosity, compact the structure and enhance the corrosion resistance of the coating, Zn-Al-Mg-RE coating system was prepared by high velocity arc spraying. The surface appears, phase composition and electrochemical properties of the coating were characterized by scanning electron microscope, X-ray radiation diffaction and electrochemical workstation. The results indicated that the coatings were compact. The coatings were mainly zinc and aluminum phase. In corrosion of immersion, the reaction resistance and coating resistance of coatings quickly become bigger, the surface of coatings become more compact, and the corrosion reaction is more difficult. Electrochemical tests showed that the coating had excellent corrosion resistance. The electrochemical protection and self-sealing effect of coatings can have long-term effects on anticorrosion.

Study on Corrosion Resistance and Mechanical Property of Welding HAZ Treated by Laser Surface Remelting

2013 ◽  
Vol 734-737 ◽  
pp. 2346-2350 ◽  
Author(s):  
Yan Li Li ◽  
Jia Rui Qi ◽  
Dan Feng Zhang ◽  
Ji Liu ◽  
Chao Li
Keyword(s):  
Mechanical Property ◽  
Corrosion Resistance ◽  
Corrosion Current ◽  
Processing Parameters ◽  
Electrochemical Analysis ◽  
Constructional Steel ◽  
Orthogonal Test ◽  
Laser Surface ◽  
Laser Remelting ◽  
Laser Surface Remelting

Welding is a main joint way of the alloy constructional steel. However, the welding HAZ is very sensitive to corrosion. In order to increase the corrosion resistance of the welding HAZ without reducing mechanical property of the parts simultaneously, the laser surface remelting was used to treat the welding HAZ in this study. According to the results of the orthogonal test, the optimized processing parameters were obtained. Based on the electrochemical analysis, the corrosion current of 30CrMnSi welding HAZ can be decreased by laser remelting technology. The corrosion resistance of the HAZ can be improved effectively. At the same time, the mechanical property of the treated welding HAZ was better compared with the untreated.

Alumina Sol-Gel Films and Alodine Films on Al 2024 Alloy

2011 ◽  
Vol 356-360 ◽  
pp. 364-367
Author(s):  
Qi Zhou ◽  
Xuan Xiao ◽  
Da Li Zhao ◽  
En Jun Song
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Film Surface ◽  
Corrosion Current ◽  
Promising Alternative ◽  
Gel Film ◽  
Alumina Sol ◽  
Sol Gel Films

Development of the sol-gel films for painting pretreatment of aluminium alloy is to replace bichromate conversion films such as Alodine. Corrosion resistance of Alodine film and sol-gel film were evaluated through potentiodynamic polarization curves, electrochemical impedance spectroscopy, salt spraying and acidic dropping solution. Sol-gel film is almost the same as Alodine film at the film surface density, salt spraying resistance and adhesion with painting coating. Changing color times of dropping solution on sol-gel film is shorter than Alodine film. But the corrosion current of sol-gel film is lower than Alodine and the impedance value is higher than Alodine in 35g/L NaCl solution. Mechanism of corrosion resistance of alumina sol-gel film is that the cathode reaction and anodic reactions are restrained by sol-gel film in the Cl- corrosive medium. The EIS of sol-gel film consisted of only a single capacitive arc with one time constant. Sol-gel coating can prevent or delay the corrosive solution from infiltrating the substrate for its better isolation function, thus protecting 2024 aluminium alloy from corrosion. Sol-gel films can improve corrosion resistance of aluminum alloy and have the same adhesion as Alodine film. It will be a promising alternative pretreatment for aluminum alloys prior to painting.

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