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It is shown that complete derusting of structural steel is not necessary if rust converter which can convert adherent rust into a protective coating is used. The performance of the rust converter developed by the authors is described in this paper.

This paper aims to prepare a residual rust epoxy coating by adding different quantities of phytic acid (PA) on the surface of the rusty steel and investigate the corrosion protection of PA and its action mechanisms.

A residual rust epoxy coating by adding different quantities of PA was prepared on the surface of the rusty steel. The influence of PA on the corrosion resistance of epoxy-coated rusty steel was investigated by means of electrochemical impedance spectroscopy and adhesion testing.

Results indicated that PA can substantially improve the corrosion resistance of epoxy-coated rusty steel. This improvement is due to the reaction of PA with residual rust and generation of new compounds with protection properties and increased adhesive strength effects on the coating/metal interface. The coating showed better protection performance when 2 per cent PA was added.

Considering the structure of the active groups, PA has strong chelating capability with many metal ions and can form stable complex compounds on the surface of a metal substrate, thereby improving corrosion resistance. In recent years, PA has been reported to be useful in the conversion of coatings or as green corrosion inhibitor. To the best of the authors’ knowledge, few studies have reported the use of PA as a rust converter or residual rust coating. The present work aims to improve the corrosion resistance of residual rust epoxy coating by adding PA.

The aim of the present work was to compare the performance of two coating systems applied on steel specimens. The first of them demands sandblasting pretreatment of the metal surface while the second one, which does not need it, leads to rust transformation. These systems were examined in three corrosive environments i.e. a geothermal fluid of low enthalpy, a 3.5 wt per cent NaCl solution and a 5wt per cent NaCl in a salt spray cabinet. The anticorrosive capability of the two coating systems was evaluated at predetermined exposure times by mass loss measurements of the steel substrate, by potentiodynamic polarization curves and by the half‐cell potential time evolution. Visual examination of the degree of rusting and blistering was also carried out. The results indicate that both coating systems exhibit almost similar protective behavior under the same conditions of pretreatment. In all cases, the corrosion rate increases with the increase of the surface roughness.

Silicone Compound Silicone compound MS 5 was originally developed as a lubricant for silver‐plated switch contacts and instrument movements and is stated subsequently to have found many other fields of application due to its ability to retain excellent dielectric properties after long exposure to wet or humid conditions. In addition to its high degree of water‐repellency, it is resistant to chemical attack, salt spray and fungi.

Other exhibits were previewed in the October issue

A self‐priming floor coating which may be applied by squeegee has been described recently. It is intended primarily for concrete to which it provides long life and attractive appearance.

Anti corrosive lubricant for submerged locations. Wet Lube solid film, anti corrosive lubricant is a blend of natural fats, mineral oils, graphite, hydrophobic agents and anti corrosive pigments formulated specifically for the prevention of corrosion and the elimination of seizures in machinery working in permanently or intermittently submerged locations or operating in damp or moist conditions.

The purpose of this paper is to study the ability of commercial tara powder to convert rust into iron tannate and evaluate their use as raw material for the formulation of water based rust converter.

Water-borne acrylic primers were formulated with tara powder and aqueous tara extract and applied on steel rusted by three different methods. The conversion of rusted steel by tara tannins was studied by X-ray diffraction spectroscopy, infrared spectroscopy and scanning electron microscopy. The acrylic primers, containing hydrolysable tannins, were coated with alkyd finish and were evaluated in comparison to commercial systems in accelerated corrosion tests. The corrosion inhibition effects of tara powder on mild steel in 0.1M NaCl were studied by DC electrochemical techniques.

Tara tannin converts rust to ferric tannate and increases the magnetite content of rusted steel. The water-based acrylic primer formulated with aqueous extract of tara, alkyd-coated finish, showed performance equivalent to pure alkyd system.

The chlorides content in the commercial tara powder can be screened the beneficial effect of hydrolysable tannins to convert rust. Furthermore, the water-based rust converter formulated with acrylic resin may be sensitive to salt contamination of rust.

Hydrolysable tannins from commercial tara powder have not been studied yet in its application to the development of rust converters. A water-based primer formulated with commercial tara powder developed for the effective treatment of rusted surfaces can be of interest as an environmentally friendly to current commercial approaches.

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.

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.

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.

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

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

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

It must be first of all asked what rust really is. The question may seem to have an obvious answer. Anybody who has had anything at all to do with iron is acquainted with the effect of rust. Nevertheless, it has to be admitted that even a number of researchers who have dedicated themselves to the subject do not have such clear ideas about it as might be assumed on the first approach. The cause of rust has always been, and still is, a subject of research and discussion, especially in the light of modern electrochemical theory which indicates to us very clearly that to attribute to rust the binomial ‘water+atmospheric oxygen’ alone is a solution which is far too simplistic. A lot of theories have been put forward in this matter, but we shall obviously not have time to study them all. According to J. N. Friend, iron which has been subjected to the combined attack of water vapour and atmospheric oxygen only corrodes quickly when carbon dioxide is present, even in small quantities.