Volume 62 (2018): Issue 2 (May 2018)

This work presents the preparation of coatings of aluminium and AlCr₆Fe₂ alloy on magnesium alloy AZ91 with metallurgical bonding. Coatings were prepared by plasma spraying system WSP^®-H 500. This metallurgical bond (sub-layer) is formed by an eutectic structure consisting of the intermetallic phase Mg¹⁷Al¹² and the solid solution of magnesium and aluminium. In this work, the layers were studied using electrochemical impedance spectroscopy (EIS). It was shown that there is a several fold increase of the polarization resistance (R_cν) of plasma-sprayed coatings of aluminium and AlCr₆Fe₂ alloy, compared with uncoated AZ91 in borate buffer with pH 9.1.

The actual industrial trend is focused on weight reduction of constructions while preserving strength properties. For this purpose, conventional steel are replaced by high strength steels.. The aim of this study was to evaluate the effects of mechanical surface pre-treatment on corrosion resistance of high strength low alloy steel Domex 700 before and after surface treatment by manganese phosphating. Tested environment was 0,1M NaCl solution. Evaluation of mechanical pre-treatment and phosphating effects on corrosion resistance was realized by electrochemical measurements: potentiodynamic polarization measurements (Tafel analysis) and electrochemical impedance spectroscopy (equivalent circuits). From resulsts it is possible to conclude, that creation of manganese phosphate layer on ground and shot peened steel surface significantly increases the corrosion resistance of Domex 700 steel.

This article was focused on the evaluation of neutral salt spray test effect (according to ISO 9124), procedure E4, on mechanical properties of load-bearing adhesive joints. The study also comprises the influence of substrate material (mild steel, aluminum alloys) and substrate surface roughness (verified by optical confocal microscopy). The experimental program contained acrylate-based adhesive and hybrid silicone polyurethane based adhesive which were applied in double lap joints loaded by shear.

There have been revealed and summarized the regularities in biocorrosion of steel 17G1S-U, which is traditionally used for manufacturing oil and gas mains. The basic regularities of biocorrosion processes in the 17G1S-U pipe steel under the influence of SRB Desulfovibrio Sp. strains Kyiv-10 was obtained by weight-loss testing and surface analysis techniques. Effective inhibitors are proposed, which allow protecting steel 17G1S-U against the development of anaerobic corrosion under the influence of sulfate-reducing bacteria (SRB). The effectiveness of inhibitors is estimated by the degree of their protective effect. The porous structure of the surface film contributes to the initiation of localized corrosion. Damage analysis of the specimen surface corroded under different test conditions was performed.

Copper is widely used metal for industrial and public purposes due to its good corrosion resistance and excellent electrical conductivity. In indoor atmospheric environments with low level of air pollution the corrosion rate of copper is very low and it is not affected by slight increasing of temperature or relative humidity. In many indoor environment hydrogen sulphide (H₂S) occurs and significantly affects the copper corrosion. CuS is a loose of black corrosion product which can’t form protective film on copper surface and promote corrosion by adsorption of moisture as carrier. In sulphide presence, the corrosion product is chalcocite Cu₂S. Copper corrosion attack by H₂S low concentration caused significant failure of electronic, electric equipment but also other copper parts as tubes, etc. These corrosion films can form an insulating layer on the contact surfaces causing electrical failures on the electronic devices.