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Anodic protection (A.P.) for corrosion control is based on the principle of protecting a metal or alloy from corrosion by raising the electrochemical potential of its surface to a value at which a protective oxide film (passive film) is formed and maintained. The principles of design of anodic protection systems are not very well developed. This paper discusses several important basic design concepts and describes several equations which can be used for the design and optimization of anodic protection systems for corrosion control.

Pitting inhibition efficiency of SO₄⁻ and NO₃⁻ on AISI 316L stainless steel in contact with Cl⁻-containing fiber dyeing solutions together with the influence of the anions on absorption behavior of the solutions were investigated. The purpose of the study is to experimentally determine an optimized dyeing solution efficient on both – inhibition of the steel’s pitting and exhaustion of the dyes dissolved.

Methods such as electrochemical cyclic polarization, UV-visible range spectrophotometry and scanning electron microscopy have been used to assess the performance of two inhibitors on both pitting inhibition of the steel and dissolving ability over the reactive dyes. To find out a promising dyeing solution mixture in both aspects, Cl content of the original dyeing solution was replaced gradually with the inhibiting anions, where the total anionic content was kept constant to unchange the dye exhaustion potential of the solution. Then, those solutions came out with diverse pitting inhibition, and dye absorption levels were compared together for reducing/avoiding the pitting issues of the reactive dyeing vessels of the industry.

Rather high absorption levels detected by visible range spectrophotometry on the solutions showing sound inhibition levels indicated possibility of unaltered reactive dyeing qualities with an enhanced vessel lifetime as the inhibitive anions replace Cl⁻. Nitrate performed better than sulfate both on inhibition and absorption in the dyeing solutions. Also, 316L vessels became open to an extra anodic protection in inhibitor added solutions.

The findings are valid for a certain group of reactive dyes and dyeing solutions held at 70°C. However, the testing methods are available to almost any dyeing solution and dyeing temperature.

The work presents a combined testing of pitting inhibition and absorption behavior of dyeing solutions involving Cl⁻ that has not been reported so far. It shows that solution recipes least harmful to the steel vessels can be outlined for various reactive or other types of dye groups.

The industrial expansion of the post‐war period has resulted in the development of new products and processes, specialised equipment and new materials of construction. Materials science, technology and engineering, has emerged as an independent discipline during the last decade. These changes have brought up the importance of corrosion problems and the urgency to apply preventive methods. It is probably true to say at the present time that the losses due to metallic corrosion give a fair index of the industrial prosperity of a nation. A developing country like India had to face the challenge posed by corrosion, and there is now an increasing awareness of the imperative need for corrosion research and the application of the findings to meet specific situations.

The Second International Congress was organised in the form of 11 major topics arranged as symposia ranging in subject matter from cathodic protection through inhibition and oxidation to stress corrosion. It involved, in total, the presentation of about 114 Papers and five plenary lectures. With such a mass of information at his disposal, a delegate to the Congress had indeed to be very selective to obtain even a rational cross‐section of the subjects discussed.

CORROSIVE EMULSIONS AT SEA. Furnace oil fuel burnt in marine boilers is liable to form stable emulsions when contaminated with sea‐water. Such emulsions cause a number of troubles, chief of which are corrosion of tubes and slagging of refractories, making frequent refining of furnaces necessary, due to the salt contained in the sea‐water. The stability of the emulsions varies considerably with the source of the oil fuel, but if conditions of emulsification are sufficiently severe, stable emulsions can be made with practically any furnace fuel oil. British ships which put salt water ballast into fuel tanks are required by law to use an oily water separator when deballasting, but the oil recovered from such a separator can contain as much as 30% by weight sea‐water.

Corrosion is the degradation of metals by chemical or electrochemical reaction with loss of their physical properties in specific areas or overall. Every year in industrialised countries the losses due to corrosion are enormous — roughly about 3.5 to 4.2% of a country's GDP, and running into billions of dollars. A significant part of these losses can be avoided by putting into practice existing corrosion control measures in a systematic manner.

A general survey is made of the techniques currently employed in corrosion studies. The application of both physical‐chemical and physical techniques is discussed. The majority of the techniques described could be used at some time or other by any corrosion laboratory either directly or indirectly. It is only by making such a wide coverage that a detailed picture of a corrosion process can be understood and the significance of alloying and corroding media (be it gas or liquid) appreciated.

The aim of this paper is to present the modernization of an old cathodic protection system installed on the legs of an offshore platform and to discuss the results of the research performed in order to investigate the anticorrosive effectiveness of this solution.

The modernization of the cathodic protection system consisted of connecting to the platform legs a sacrificial anode system placed at the sea bottom. The effectiveness of the modernized system was assessed on the basis of the measurements of the potential profiles of the platform legs, i.e. the distribution of their potential over the entire length.

After connecting sacrificial anode systems, the potential of the legs kept changing towards more negative values. The extent of cathodic polarization increased, and already after a week the potential of the legs fell within the range of full cathodic protection almost along their entire length. The polarization was higher at the lower parts and decreased close to the water surface, which was a result of the distance of a given fragment from the anodic system. The results of the measurements confirmed the correctness of the design assumptions and the effectiveness of the performed modernization.

The results obtained show that the modernization of the cathodic protection system on the legs of an offshore platform consisting of connecting sacrificial anode systems placed at the sea bottom can ensure the achievement of full cathodic protection potential for long legs (these were 80 m long in this study).

By adding a Ce salt and an Nd salt to an anodizing electrolyte, modified anodic films are obtained on aluminum surfaces. This paper aims to study the effects of rare‐earth elements on the corrosion resistance of the anode film.

The crystalline film was studied by X‐ray diffraction. The methods of scanning electron microscope, energy dispersive X‐ray analysis, electrochemical polarization, and electrochemical impedance spectroscopy (EIS) were used to characterize the properties of the films.

After rare‐earth element modification, the pores of the porous layer were very evidently smaller, the anodic film was more compact, and the thickness and hardness of the films had increased. The corrosion resistance of the anodic films modified with rare‐earth elements clearly was improved in neutral, acidic, and basic NaCl solutions. Ce showed a better effect than Nd in increasing the corrosion resistance of the films, and the film modified with Ce+Nd showed the highest corrosion resistance. EIS analysis showed that the impedances of both the barrier layer and porous layer of the anodic films increased after modification with the rare‐earth elements, indicating that the anodizing process was affected by the presence of the rare‐earth elements.

The results presented in this paper offer a foundation for further research and application of rare‐earth elements in aluminum anodic oxide films.

The purpose of this paper is to study of the effect of carboxylic acids additions to the anodising bath on the subsequent corrosion and stress corrosion cracking (SCC) tendencies of anodised 1050 Al‐Alloy in 3M NaCl solution.

The study was carried out using SCC tests and electrochemical cyclic potentiodynamic measurements at a high or a slow scan rates. The anodic coatings were prepared electrolytically in a bath of 4 M H2SO4, with and without additions of 0.015 M oxalic, malonic, tartaric, maleic, or citric acids. The consequent thicknesses and packing densities of the coatings were measured.

The SCC behaviour was found to vary with both anodising conditions and stress level. The addition of carboxylic acids in the anodising bath increased the protective properties of the coating. In corrosion conditions without stress, the addition of the carboxylic acids decreased the susceptibility to pitting corrosion, the effect depending on the presence or absence of corrosion products. The addition of the carboxylic acids during anodising leads to the formation of less porous and more compact oxide layers and increases the anticorrosive properties of the coatings. The benefits were most pronounced for the coating prepared in the presence of maleic acid.

The belief that the effect of carboxylic acids on the corrosion and SCC behaviour of Al‐Alloys is due to the absorption of these compounds on the metal surface and the formation of complexes on it, depending on the structure and carbonic chain of these compounds, remains yet to be confirmed.

Anodic coatings prepared in an electrolytic bath containing carboxylic acids can be used for the protection of aluminium alloys against corrosion.

The paper provides information regarding the improvement of the anticorrosive properties of electrolytically prepared anodic coatings on aluminium alloys.