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Mechanisms of degradation of organic coatings

Abstract

An overview of protection mechanisms of organic coatings for metallic constructions and products is given. The barrier effect of coatings and protection in local defects are discussed. Basic degradation mechanisms of organic coatings such as anodic and cathodic delamination in vicinity of defects, osmotic and cathodic blistering, mechanical stress assisted blistering, loss of adhesion and chalking are described. Appropriate laboratory tests are proposed for each degradation mode.

Open access
Study of damage extent to glass fibre in glass-fibre fabric reinforcement during exposure simulating concrete pore solution

Abstract

The paper evaluates extent of corrosion damage to composite glass-fibre fabric reinforcement in environment simulating concrete pore solutions (pH 12.6, 13.0, 13.5) and carbonated concrete contaminated with chlorides (pH 8.1 + Cl-) using the FT-IR and SEM/EDS techniques. Also, the effect of corrosion damage on tensile strength of segmented glass fibre as well as the presence of specific protective organic coating on glass fibre were studied. The results demonstrate local corrosion damage of samples at pH 13.5 and on the other hand high stability in environment simulating carbonated concrete and carbonated concrete contaminated with chlorides. The study also suggests unevenness of organic coating with occurrence of localized porosity which is related to aforementioned corrosion damage. Corrosion damage in FT-IR spectra manifests by changes in peaks signalling hydrolysis of protective organic coating and occurrence of peaks suggesting presence of Ca2+ rich corrosion products.

Open access
Copper and copper patina

Abstract

This article is aimed at summarizing knowledge about copper and patina that is formed on the surface of copper. The article describes chemical processes in patina formation and explains the difference between natural and artificial patina, as well as some methods used in the investigation of patina such as XRD analysis, EIS analysis, Raman spectroscopy

Open access
Corrosion problems and solutions in oil, gas, refining and petrochemical industry

Abstract

The aim of this work is to describe and analyze corrosion problems and their solutions in oil, gas, and refining industry. Corrosion phenomena and factors influencing them are discussed. Corrosion control and monitoring methods are illustrated. Corrosion management plays vital role in the solving of corrosion problems. The results are summarized in new book of the author “Corrosion Problems and Solutions in Oil Refining and Petrochemical Industry” published by Springer in 2016.

Open access
The influence of deformation on the corrosion properties of the material

Abstract

This work was focused on changes of corrosion behaviour influence of deformation. The This work focuses on changes in corrosion behaviour under the influence of deformation. The main purpose is to observe the changes caused by tensile stress. The experimental material used is steel 1.4301 and titanium GRADE 2. The measurements were carried out using a potentiostat, which measures potential changes over time and electric current. The electrolyte used was 3.5% NaCl. Corrosion properties, especially polarization resistance, corrosion potential and corrosion rate, were evaluated from the measurements. The results demonstrate the changing corrosion properties depending on deformation. The corrosion properties worsened as the deformation increased.

Open access
Inspection possibilities of metallic material surface integrity by conventional ultrasonic technique

Abstract

The article is focused on the possibilities of ultrasound surfaces control on metallic materials by conventional ultrasonic techniques. Physical principles, types of ultrasonic waves to be used for surface control are described in the theoretical part. Three surface control techniques are listed in the experimental part of article. The first technique is a common control by angle ultrasonic probe with using transverse waves. The second technique is surface control by 30-70-70 creep waves and third techniques is surface testing by Rayleigh waves. Practical examples of ultrasonic testing for all techniques are illustrated. The conclusion of the article is devoted to the advantages and limitations of the individual testing methods.

Open access
The tribological properties of Al-brasses in various environments

Abstract

Tribological properties of Al-brass pipes of various producers were studied in different environments. The tested brasses have very similar chemical composition, but they differ in microstructure due to mainly by heat treatment after cold drawing. Microstructure as well as roughness of surface influence chemical and mechanical properties which are important in operating conditions. The experiments of tribological behavior were made in various environments, dry air, cooling treated water and 3.5 % solution of NaCl at room temperature 21 ± 2°C. The tribological tests were carried out on the Linear Tribometer at normal loading 5 N by the method ball on plate for the duration of 5500 s. The measured friction coefficients were evaluated by the program DIAdem and the diagrams were created from signal generated by software NSignal Express

Open access
Anticorrosive efficiency of alkyd resin-based coatings containing Mg–Zn–Fe mixed oxide-based pigments

Abstract

Mixed oxide-based pigments Mg–Zn–Fe with different particle morphologies were prepared by high-temperature solid phase reactions. The core shell pigments containing ferric oxide and non-isometric particles of layered silicates were also prepared. The pigments were tested in paints, the pigment volume concentrations in the modified alkyd resin based binder being 5%, 10%, and 15%. The paint properties were examined by accelerated corrosion tests and by physico-mechanical tests. The effect of the pigment particle morphology on the surface hardness of the paint films was also studied. The influence of pigment volume concentration on the coating properties, and the optimum concentrations providing the most efficient anticorrosive protection were processed. A higher anticorrosion efficiency was observed for the paints with pigments possessing the lamellar particle shape.

Open access
Atmospheric corrosion models

Abstract

A number of damage functions or dose-response equation, which are compared to the atmospheric corrosion of metals with environmental parameters, have been determined in field programs ISOCORRAG, UN ECE ICP Materials Exposure Programme and Multi-Assess. The all of these dose-response equations are derived on field exposure results performed during period 1986-1995 where the SO2 level was relative high at urban and very high at industrial test sites. Several exposure programmes, national and international, of structural metals’ atmospheric corrosion were conducted since the 1970s on Czech atmospheric test sites including on-site measurement of environmental data. All data from these exposure programs were compared with prediction models.

Open access
Electrodeposition of multicomponent Co–Cr–Fe–Mn–Ni alloy

Abstract

This work is focused on the initial realization of a multi-component coating deposition from the aqueous solution. The Coating composed of the elements Co-Cr-Fe-Mn-Ni was prepared by electroplating process. The chosen substrate was copper. The purpose of the work was to apply the high entropy alloy, which is defined as alloy with structure of a solid solution containing five or more elements in an approximately equal atomic ratio. The use of electrodeposition in this area is rare. The conditions of the plating process, the percentage of the metal ions and cohesion of the layers were studied. The morphology of the excluded coatings was monitored by scanning electron microscopy and their elemental composition was verified by the EDS analysis. The wear resistant features were examined approximately before and consequently also after the thermal resistance testing.

Open access