Search results

1 – 10 of over 2000
Article
Publication date: 14 February 2019

Xiaobo Wang, Zhipeng Li, Wen Zhan, Jesong Tu, Xiaohua Zuo, Xiangyi Deng and Boyi Gui

This study aims to expand the reliability and special functions of lightweight materials for high-end equipment and green manufacturing, so that it is the first such…

Abstract

Purpose

This study aims to expand the reliability and special functions of lightweight materials for high-end equipment and green manufacturing, so that it is the first such research to carry out nano-composite technology of nickel-coated carbon nanotubes (Ni-CNTs)-based titanium-zirconium chemical conversion on aluminum alloy substrate.

Design/methodology/approach

Corrosion behavior of various coatings was investigated using dropping corrosion test, linear polarization and electrochemical impedance spectroscopy. The results showed that the corrosion resistance of the nano-composite conversion coatings was significantly improved to compare with the conventional titanium-zirconium conversion coating. The morphology and microdomain characteristics of the nano-composite conversion coatings were characterized by SEM/eds/EPMA, which indicated that the CNT or Ni-CNTs addition promoting the integrity coverage of coatings in a short time.

Findings

Surface morphology of titanium-zirconium (Ti-Zr)/Ni-CNT specimens exhibited smooth, compact and little pores. The nano-composite conversion coatings are mainly composed of Al, O, C and Ti elements and contain a small amount of F and Zr elements, which illuminated that CNT or Ni-CNT addition could co-deposit with aluminum and titanium metal oxides.

Originality/value

The study of corrosion resistance of nano-composite conversion coatings and the micro-zone film-formation characteristics would be provided theoretical support for the development of basic research on surface treatment of aluminum alloys.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 25 July 2019

Tianji Xing, Lixia Ying, Chunxi Wu, Zhen Fu and Guixiang Wang

The purpose of this paper is to improve binding force between the coating and the steel substrate by using chemical modification on the steel surface; at the same time, it…

Abstract

Purpose

The purpose of this paper is to improve binding force between the coating and the steel substrate by using chemical modification on the steel surface; at the same time, it can also increase the corrosion resistance of the coating.

Design/methodology/approach

The main components of the conversion film include tannic acid, sodium molybdate and silane coupling agent KH560. After the preparation was completed, the samples were tested and analyzed, including surface morphology, conversion film components, bonding force with organic resins and corrosion resistance. Finally, it drew a conclusion that the conversion film can greatly improve the bonding strength of the steel substrate and epoxy resin.

Findings

When the content of tannic acid is 4 g/L meanwhile the content of KH560 is 20 g/L, the conversion film has the strongest binding force with epoxy resin, from 2.15 Mpa of untreated steel to 4.60 Mpa, growth of 140 per cent. At the same time, the resulting conversion film also improves the corrosion resistance of the steel surface by a small margin.

Originality/value

A method of enhancing the bond between an epoxy coating and steel is provided. Verify the mechanism of this method.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 8 August 2022

Xinxiang Li, Wen Zhan, Xuzheng Qian, Yunhe Zu, Fan Xie, Feng Tian, Xiaohui Liu and Yunhu Ding

This paper aims to focus the synchronous chemical conversion technology–based titanium/zirconium composite on 6061, 7075 aluminum alloys and galvanized steel.

Abstract

Purpose

This paper aims to focus the synchronous chemical conversion technology–based titanium/zirconium composite on 6061, 7075 aluminum alloys and galvanized steel.

Design/methodology/approach

The effects of pH, temperature, reaction time and other process parameters on the corrosion resistance of the three metal surface coatings were investigated by copper sulfate drop and electrochemical corrosion performance tests under a certain content of H2TiF6 and H2ZrF6. The surface morphology and element distribution of the conversion coating were analyzed by scanning electron microscope and X-ray photoelectron spectroscopy.

Findings

The results show that the optimal synchronization chemical conversion conditions of 6061/7075 aluminum alloys/galvanized steel are controlled as follows: H2TiF6 2.2 mL/L, H2ZrF6 1 mL/L, pH 3.9, conversion temperature 35°C and conversion time 120 s.

Originality/value

Multi-metals chemical conversion coating can be obtained simultaneously with uniform corrosion resistance and surface morphology. The presence of microdomain features in multiple metals facilitates simultaneous chemical conversion into coatings.

Details

Anti-Corrosion Methods and Materials, vol. 69 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 3 May 2016

Yuanfeng Jia, Nana Ren, Huadong Yue, Jianru Deng and Yali Liu

The paper developed a novel gallic acid-based rust conversion emulsion (RCE) that is applied in the treatment of rusted steels. The purpose of this paper is to investigate…

Abstract

Purpose

The paper developed a novel gallic acid-based rust conversion emulsion (RCE) that is applied in the treatment of rusted steels. The purpose of this paper is to investigate the methods for the synthesis of RCE and study the mechanism of rust conversion.

Design/methodology/approach

Conversion emulsion was prepared using styrene, acrylate and self-developed gallic acid (GA)-based rust converter (GRC) via seed emulsion polymerisation. The polymerisable GRC was synthesised by the ring-opening reaction of glycidyl methacrylate with natural GA. The effects of the GRC dosage and its feeding modes on the RCE synthesis were analysed. The corrosion resistance, surface morphology, composition and mechanism of rust conversion coatings were studied using electrochemical tests, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively.

Findings

The results showed that conversion coating on rusted steels treated with RCE, with various dosages of GRC (weight per cent), synthesised using seed emulsion polymerisation, exhibited the best adhesion and corrosion resistance. Raman spectroscopy revealed that RCE converted the original multiphase rust into stable crystalline phases of α-Fe2O3 and Fe3O4. According to XPS and energy dispersive X-ray analysis, the phenolic hydroxyl groups of RCE were proposed to chelate with Fe ions to form macromolecular ferrum compounds.

Research limitations/implications

The pre-rusted steels demonstrated a better corrosion resistance than rust-free steels after treatment with RCE.

Practical implications

The paper developed a novel GA-based RCE with high efficiency and environment-friendly method.

Originality/value

This work is expected to replace the conventional rust conversion paints and cause a significant impact on extending the service life of rusted steels.

Details

Pigment & Resin Technology, vol. 45 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 June 2015

Jie Sun and Gang Wang

The purpose of this paper was to prepare the cerium-based conversion coating on AZ91D magnesium alloy, and its compositions, micro-morphology, corrosion resistance and the…

Abstract

Purpose

The purpose of this paper was to prepare the cerium-based conversion coating on AZ91D magnesium alloy, and its compositions, micro-morphology, corrosion resistance and the chemical valence state of the film elements were investigated.

Design/methodology/approach

The methodology comprised preparation of coatings at different temperatures, which then were characterized using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, an electrochemistry workstation and by means of X-ray photoelectron spectroscopy.

Findings

The conversion coating had a micro-cracked morphology. The conversion coatings were composed of MgO (or Mg-OH), CeO2 and Ce2O3. The best corrosion resistance of the cerium passivation film appeared when the treatment temperature was about 35°C.

Originality/value

The corrosion current densities of conversion coatings were lower by one to two orders of magnitude than the corrosion current density of the blank sample. The rare earth passivation coating prepared under the best condition could reduce the corrosion current to 3.548 × 10−6 A/cm2.

Details

Anti-Corrosion Methods and Materials, vol. 62 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 3 November 2022

Thi Thanh Huong Nguyen, Nam Pham Thi, Thang Le Ba, Vy Uong Van, Bao Le Duc and Tuan Anh Nguyen

This study aims to enhance to corrosion protection of NiZn-plated steel by electroplating multilayer coating.

Abstract

Purpose

This study aims to enhance to corrosion protection of NiZn-plated steel by electroplating multilayer coating.

Design/methodology/approach

The multilayer coating consists of three layers on mild steel substrate, such as Cr3+ chromate conversion layer (CCC), electrodeposited nanosilica zinc-nickel composite layer (ZnNiSi) and electrodeposited zinc-nickel alloy layer (ZnNi). Its morphology, composition and corrosion behaviour were investigated by various methods.

Findings

Polarization curves indicated that polarization resistance and corrosion current density of CCC/ZnNiSi/ZnNi/Fe (6.956 kO.cm2; 2.56 µA.cm−2) were two times higher and five times lower than that of ZnNiSi/ZnNi/Fe (3.42 kO.cm2; 12.52 µA.cm−2), respectively. From electrochemical impedance spectroscopy data, charge transfer resistances were 1.344, 2.550 and 2.312 kO.cm2 for ZnNi, ZnNiSi/ZnNi and CCC/ZnNiSi/ZnNi, respectively. Salt spray test indicated that after 48 h, surface of ZnNi and ZnNiSi was covered by white rust, whereas no white rust was observed on surface of CCC/ZnNiSi/ZnNi. After 600 h, there were red rust spots (1% surface coverage) on surface of Zn-Ni, whereas only white rust was observed on both ZnNiSi/ZnNi (100% surface coverage) and CCC/ZnNiSi/ZnNi (10% surface coverage).

Originality/value

Multilayer coating enhanced significantly the corrosion protection for steel, as compared to the single-layer coating.

Details

Anti-Corrosion Methods and Materials, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 4 December 2018

Reza Hosseini Rad, Mansoor Toorani and HamidReza Zarei

This paper aims to increase protection behavior of epoxy coating on aluminum alloys with plasma electrolitic oxidation (PEO) process as pretreatment and to investigate the…

Abstract

Purpose

This paper aims to increase protection behavior of epoxy coating on aluminum alloys with plasma electrolitic oxidation (PEO) process as pretreatment and to investigate the corrosion properties of duplex coating system on aluminum alloy.

Design/methodology/approach

The study used micro structure study, electrochemical impedance spectroscopy (EIS) investigation, water uptake investigation and pull-off test.

Findings

This study was done to investigate the effect of urea as an additive, which alters the current density and time of process parameters in the protective performance of epoxy coating on the aluminum substrate. The protective behavior of double-layer coatings was examined using EIS in 3.5 per cent NaCl solution. In addition, the adhesion strength of double-layer coatings was evaluated using pull-off test, and the results demonstrated that the adhesion strength of sample with higher content of urea and current density is about two times that of sample without PEO preparation.

Originality/value

The protective properties and adhesion strength of epoxy coating can be increased with PEO pretreatment.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 February 1998

Jyoti Lata Pandey and M.K. Banerjee

Solar selective coatings are designed and formulated for effective collection and retention of solar energy. Several types of coatings can be utilized for economical…

2442

Abstract

Solar selective coatings are designed and formulated for effective collection and retention of solar energy. Several types of coatings can be utilized for economical collection of solar energy, the most common and simplest will be ordinary non‐glass, heat resistant black paint. The coatings may be moderately selective or non‐selective absorbers, consisting of organic or inorganic matt black paints. These are easiest to apply and the least expensive of all collector coatings. In this category other types are ceramic and organic enamels and chemical or electrochemical metal conversion coatings. An impending energy crisis has already aroused interest and scientific pursuit in the field. An analysis of the state‐of‐the‐art in solar selective coatings was felt necessary at this time.

Details

Anti-Corrosion Methods and Materials, vol. 45 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 October 1997

Kevin Brown

Discusses the various applications of chromium in pre‐paint metal treatments and the restrictions being placed on their use. Gives details on equivalent non‐chromium products.

702

Abstract

Discusses the various applications of chromium in pre‐paint metal treatments and the restrictions being placed on their use. Gives details on equivalent non‐chromium products.

Details

Anti-Corrosion Methods and Materials, vol. 44 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 3 September 2019

Yong Zhou, Pei Zhang, Jinping Xiong and Fuan Yan

A chromate conversion coating was prepared on the surface of bare AA2024 aluminum alloy by direct immersion in the chromating treatment bath, and the corrosion behavior of…

Abstract

Purpose

A chromate conversion coating was prepared on the surface of bare AA2024 aluminum alloy by direct immersion in the chromating treatment bath, and the corrosion behavior of chromated AA2024 aluminum alloy in 3.5 per cent NaCl solution was studied by electrochemical measurement and microstructural observation.

Design/methodology/approach

According to the polarization curve test and the scanning electron microscope observation, the corrosion evolution of chromated AA2024 in 3.5 per cent NaCl solution was divided into the following three stages: coating failure, pitting corrosion and intergranular corrosion (IGC).

Findings

In the first stage, the chromate coating degraded gradually due to the combined action of chloride anions and water molecules, resulting in the complete exposure of AA2024 substrate to 3.5 per cent NaCl solution. Subsequently, in the second stage, chloride anions adsorbed at the sites of θ phase (Al2Cu) and S phase (Al2CuMg) on the AA2024 surface preferentially, and some corrosion pits initiated at the above two sites and propagated towards the deep of crystal grains. However, the propagation of a pit terminated when the pit front arrived at the adjacent grain boundary, where the initiation of IGC occurred.

Originality/value

Finally, in the third stage, the corrosion proceeded along the continuous grain boundary net and penetrated the internal of AA2024 substrate, resulting in the propagation of IGC. The related corrosion mechanisms for the bare and the chromated AA2024 were also discussed.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

1 – 10 of over 2000