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Article
Publication date: 1 October 1982

G.W. Kapse and L.K. Aggarwal

Corrosion protection efficiency of any protective system depends not only on the nature and quality of the coating system used but also on the condition of the mrface on…

Abstract

Corrosion protection efficiency of any protective system depends not only on the nature and quality of the coating system used but also on the condition of the mrface on which it is to be applied. Various metal cleaning methods include (a) chemical cleaning — solvent degreasing, alkali cleaning and acid pickling (b) mechanical cleaning — shot blasting and (c) chemical conversion coatings — phosphating. Several of the recent advances in the field of prepaint treatment of steel have had as an objective the provision of an intrinsically fine, compact, well adhered zinc phosphate coating. Studies in this direction have been carried out in Central Building Research Institute, Roorkee and conditions for a suitable phosphating process have been optimised. Some work on the development of zinc rich paints based on both inorganic as well as organic binders have already been reported. The study has been extended by evaluating the performance of these zinc rich coatings on phosphated steel panels. In this report the performance of the above mentioned coatings when applied on the phosphated steel panels have been discussed. The studies reported include the preparation of the phosphated mild steel panels having three levels of coating wight ranging between 1.5–7.5 g/m2 (obtained by varying only the immersion time and keeping other parameters similar). A cost of zinc rich paint (75m?) based on either sodium silicate or chlorinated rubber binder was then applied on these panels along with the unphosphated ones. Comparison of the corrosion protection efficiency of the various systems thus obtained was carried out by using both laboratory and accelerated laboratory tests as well as by outdoor exposure studies. The performance of the coatings on phosphated panels has been remarkedly satisfactory as compared to the unphosphated panels. This is particularly so when the coating weight of the phosphate layer is between 4.5–7.5 g/m2; there is not any marked difference in the performance of paints applied on a phosphated layer with a coating weight of about 1.5 g/m2 as compared to the unphosphated panels.

Details

Anti-Corrosion Methods and Materials, vol. 29 no. 10
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 14 June 2013

Dong Jiang, Litian Hu and Dapeng Feng

The purpose of this paper is to synthesize a novel kind of crown‐type phosphate ionic liquids with better tribological properties for steel/Al system. The anions of…

Abstract

Purpose

The purpose of this paper is to synthesize a novel kind of crown‐type phosphate ionic liquids with better tribological properties for steel/Al system. The anions of crown‐type phosphate ionic liquids contain no F element, which are non‐corrosive to metal.

Design/methodology/approach

To improve the tribological properties of ionic liquid lubricants for the extremely difficult system of the steel‐against‐aluminum metal couple, novel crown‐type phosphate ionic liquids were prepared. The tribological properties of the crown‐type phosphate ionic liquids were evaluated at different loads and frequencies on an Optical SRV oscillating friction and wear tester. The morphology and chemical compounds of the wear scars were investigated by scanning electron microscope (SEM) and X‐ray photoelectron spectroscopy (XPS).

Findings

Compared with conventional ionic liquids, the novel crown‐type phosphate ionic liquids prepared in the present work exhibit a more excellent anti‐wear ability for steel/Al2024 contact at different loads and frequencies. By the morphological analysis with SEM, less debris was observed in the worn surface lubricated with crown‐type phosphate ionic liquids, though more debris was observed when lubricated with LB106 and LP106. By the XPS analysis, boundary lubrication film composed of aluminum (III) oxide, organometallic compounds, and silicon aluminum phosphate were found in the worn surface. Namely, the tribological behaviors of the crown‐type phosphate ionic liquids could be attributed to their stronger adsorption and tribochemical interactions with the Al alloys.

Research limitations/implications

Because of the higher mean friction coefficients of crown‐type phosphate ionic liquids in the research, researchers are encouraged to modify their structure for better tribological properties.

Practical implications

The crown‐type phosphate ionic liquid exhibited better anti‐wear performance for steel/aluminum contact than the conventional ionic liquids containing F element. This will expand the application of high strength aluminum alloys.

Originality/value

The phosphate ionic liquid is a non‐corrosive liquid and would not cause metal corrosion. Also, the tribological properties of crown‐type phosphate ionic liquid with steel/aluminum contact are better than that of conventional ionic liquids. By the designing of molecular structure, new phosphate ionic liquids will exhibit excellent tribological properties: lower wear volume and lower friction coefficient.

Details

Industrial Lubrication and Tribology, vol. 65 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 3 May 2016

Jiansan Li, Yali Li, Yanqin Chen, Jiawei Sun, Chunxiao Wang, Yingcai Zheng and Huiting Zhong

This paper aims to report the influence of hexamethylenetetramine (HMTA) on phosphate coatings formed on AZ31 magnesium alloys.

Abstract

Purpose

This paper aims to report the influence of hexamethylenetetramine (HMTA) on phosphate coatings formed on AZ31 magnesium alloys.

Design/methodology/approach

These phosphate coatings were obtained by immersing magnesium alloys in phosphate baths with HMTA. The morphology and composition of the phosphate coatings were investigated via scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction.

Findings

The phosphate coatings were mainly composed of CaHPO4·2H2O. The HMTA concentration in the phosphate bath influenced the crystallization and corrosion resistance of the phosphate coating.

Originality/value

The polarization curve shows that the anti-corrosion qualities of the phosphate coating were optimal when the HMTA concentration was 1.0 g/L in the phosphate bath. Electrochemical impedance spectroscopy (EIS) shows that the electrochemical impedances increased gradually when the HMTA concentration varied from 1.0 to 3.0 g/L.

Details

Anti-Corrosion Methods and Materials, vol. 63 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 August 2004

M.A. Abd El‐Ghaffar, E.A.M. Youssef and N.M. Ahmed

Historically, paints designed to protect steel and other metals have been formulated using anticorrosive chromate pigments, which are currently under environmental…

Abstract

Historically, paints designed to protect steel and other metals have been formulated using anticorrosive chromate pigments, which are currently under environmental restrictions. During the investigation reported here, various phosphate compounds. The pigments prepared were characterised using a variety of chemical and spectrophotometric methods of analysis including emission atomic absorption, transmission electron microscope, X‐ray diffraction, in addition to thermal gravimetric analysis. The pigments were also evaluated according to relevant international standard testing methods. The phosphates prepared were incorporated into anticorrosive paint formulations, to replace the imported zinc phosphate pigment, containing medium oil alkyd resin, and melamine formaldehyde resin. Paint films obtained were tested in artificial seawater for 28 days for anticorrosion properties. The results indicated that the paint films had good anticorrosive protection properties that could be attributed to the pigments prepared and the resins used.

Details

Pigment & Resin Technology, vol. 33 no. 4
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 February 1961

H.A. Holden

The phosphate treatment of metals has been in industrial use for over 50 years and is the most widely used method of treating light‐gauge steel as a preparation for…

Abstract

The phosphate treatment of metals has been in industrial use for over 50 years and is the most widely used method of treating light‐gauge steel as a preparation for painting; in addition, during the last 20 years, its use as an aid in the cold forming of steel in such operations as tube and wire drawing has been established. As a result of these trends, phosphating is now a very significant part of the whole metal finishing industry. This review includes advancements in operation, composition and use.

Details

Anti-Corrosion Methods and Materials, vol. 8 no. 2
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 1 April 2006

Hiroaki Onoda, Masakazu Kohno, Jun Tamaki, Kazuo Kojima and Hiroyuki Nariai

Aluminum phosphate is useful catalyst for many reactions. There are a lot of reports about catalytic activities of aluminum phosphate, however little reports about the…

Abstract

Aluminum phosphate is useful catalyst for many reactions. There are a lot of reports about catalytic activities of aluminum phosphate, however little reports about the relationship among the preparation, composition, catalytic activity of this phosphate. Phosphates transform to various other phosphates with hydrolysis and dehydration reactions by heating. In this work, some aluminum orthophosphates and condensed phosphates were prepared, and their compositions were estimated. Furthermore, specific surface area, acid strength, the amount of acidic sites, and the catalytic activities for the decomposition of trifluoromethane of these salts were investigated. Aluminum ortho‐ and polyphosphates were prepared in the systems of ortho‐ and poly‐phosphates. The catalytic activity for decomposition of CHF3 was related with a certain degree of specific surface area, acid strength, and the amount of acidic sites. Aluminum orthophosphate with a small amount of sodium cation had higher catalytic activity at lower temperature.

Details

Multidiscipline Modeling in Materials and Structures, vol. 2 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 18 October 2022

Reza Amini and Pooneh Kardar

This paper aims to achieve phosphating via optimal features of Mg metal as a suitable base coating, which is considered for other properties such as barrier properties…

Abstract

Purpose

This paper aims to achieve phosphating via optimal features of Mg metal as a suitable base coating, which is considered for other properties such as barrier properties against the passage of several factors.

Design/methodology/approach

In this research, in the phosphate bath, immersion time, temperature and the content of sodium nitrite as an accelerator were changed.

Findings

As a result, increasing the immersion time of AZ31 Mg alloy samples in the phosphating bath as well as increasing the ratio of sodium dodecyl sulfate (SDS) concentration to sodium nitrite concentration in the phosphating bath formulation increase the mass of phosphating formed per unit area of the Mg alloy. The results of the scanning electron microscope test showed phosphating is not completely formed in short immersion times, which is a thin and uneven layer.

Research limitations/implications

Mg and its alloys are sensitive to galvanic corrosion, which would lead to generating several holes in the metal. As such, it causes a decrease in mechanical stability as well as an unfavorable appearance.

Practical implications

Mg is used in several industries such as automobile and computer parts, mobile phones, astronaut compounds, sports goods and home appliances.

Social implications

Nevertheless, Mg has high chemical reactivity, so an oxide-hydroxide layer is formed on its surface, which has a harmful effect on the adhesion and uniformity of the coating applied on Mg.

Originality/value

By increasing the ratio of SDS concentration to sodium nitrite concentration in the phosphating bath, the corrosion resistance of the phosphating increases.

Details

Pigment & Resin Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 2 October 2021

Khalid Abdalla and Hussain Zuhailawati

The purpose of this paper is to study the effect of different concentrations of pretreatment solution of copper acetate (1, 5 and 10 g/L) on the deposition, growth and…

Abstract

Purpose

The purpose of this paper is to study the effect of different concentrations of pretreatment solution of copper acetate (1, 5 and 10 g/L) on the deposition, growth and protection ability of zinc phosphate coating.

Design/methodology/approach

Zinc phosphate coatings were deposited on steel surface by immersion method. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to study the morphological evolution and chemical analysis of formed coatings. The electrochemical performance of the coatings was evaluated via potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and immersion test in an aerated 3.5% NaCl solution.

Findings

The results showed that the activation treatment accelerated the deposition of the phosphate coating and improved its surface coverage. A higher phosphate coating weight (7.35 g/m2) and more compact structure was obtained with pretreatment solution of 1 g/L copper acetate. Electrochemical results revealed that the protection ability of the phosphated substrates was markedly enhanced after the pretreatment, and the best corrosion protection was obtained with a concentration of 1 g/L copper acetate solution. The corrosion current density of phosphated substrate was reduced by 64.9% after activation treatment with 1 g/L copper acetate solution.

Originality/value

In this investigation, dense, stable and compact zinc phosphate layers with improved corrosion resistance were formed on a carbon steel surface after activation pretreatment with copper acetate solution prior to a phosphating step.

Details

Anti-Corrosion Methods and Materials, vol. 68 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 7 November 2008

Nivin M. Ahmed

The purpose of this paper is to present a new trend of anticorrosive pigments based on bulk (core) of zinc oxide covered with a surface layer of phosphates.

Abstract

Purpose

The purpose of this paper is to present a new trend of anticorrosive pigments based on bulk (core) of zinc oxide covered with a surface layer of phosphates.

Design/methodology/approach

A new batch of pigments based on core‐shell theory containing a core (bulk) of cheap oxides covered by a layer of phosphates were prepared. These new pigments combined the properties of both components besides being more economically feasible. Simple chemical techniques were used to prepare these pigments. Characterization of these pigments using X‐ray diffraction and scanning electron microscopy was carried out. Evaluation of these pigments using international standard testing methods was estimated. These pigments were incorporated in solvent‐based paint formulations based on medium oil alkyd resin. The physico‐mechanical properties of dry films and their corrosion properties using an accelerated laboratory test in 3.5 percent NaCl for 28 days were tested.

Findings

It was found that those pigments based essentially on zinc oxide covered with a surface layer of phosphates were easily prepared, are economically feasible and can successfully replace original phosphates with similar efficiency in their corrosion protection behaviour.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics, as a reinforcing agent.

Originality/value

The prepared pigments are environmentally friendly and can replace other hazardous pigments (e.g. chromates) with almost the same quality in their performance; also they can be used in industries other than paints, e.g. paper, rubber and plastics composites.

Details

Anti-Corrosion Methods and Materials, vol. 55 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 2 November 2015

Cristiane Spagnol, Everson do Prado Banczek, Isolda Costa, Maico Taras Cunha, André Lazarin Gallina, Martha Tussolini and Paulo Rogério Pinto Rodrigues

The purpose of the paper is to show the corrosion effect of benzotriazole in comparison with iron phosphate (PFe) coating as a sealer for the PFe layer in carbon steel…

Abstract

Purpose

The purpose of the paper is to show the corrosion effect of benzotriazole in comparison with iron phosphate (PFe) coating as a sealer for the PFe layer in carbon steel paint pre-treatment and to show its ecological advantages as a more environment-friendly inhibiting compound than PFe.

Design/methodology/approach

Samples of carbon steel (SAE 1010) were phosphated in two baths, one containing iron PFe and PFe and BTAH (PFe + BTAH). Anodic potentiostatic polarization curves and electrochemical impedance spectroscopy were used to evaluate the corrosion resistance of phosphated carbon steel in 0.1 molL−1 H2SO4, 0.5 molL−1 NaCl and 0.1 molL−1 NaOH. The phosphate layers obtained were analyzed by infrared spectroscopy. Surface observation by scanning electron microscopy (SEM) showed that the PFe and PFe + BTAH layers are deposited as crystals with granular morphology. The electrochemical results showed that the PFe + BTAH coating was more effective in corrosion protection of the carbon steel.

Findings

This paper presents the application of benzotriazole as post-treatment of PFe-coated carbon steel. The results show that benzotriazole improves the phosphate layer properties. The SEM micrographs showed that the layer formed in PFe and PFe + BTAH baths consists of grain-like crystals, and infrared results revealed the BTAH presence in PFe phosphate. The corrosion resistance results showed higher efficiency associated to the PFe + BTAH phosphate layer relative to that of PFe. From the present study, results can be concluded that BTAH can be used as a post-treatment for PFe phosphate coating.

Originality/value

This paper deals with the corrosion resistance and surface carbon steel characterization of a new sealer for PFe coating, which has been prepared for this study and was never tested previously. These are candidate materials for substitution of chromium sealer. The BTAH sealer presents environmental and corrosion resistance advantages when compared with the post-treatment based on chrome. Although BTAH improves PFe layers’ properties, it is the worst phosphate coating. This manuscript has never been previously submitted and deals with original results.

Details

Anti-Corrosion Methods and Materials, vol. 62 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

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