Generally, organic coatings which contain zinc ferrites are able to protect metal substrate, most often low-carbon steel, by inhibition mechanism. Conductive polymers are using a system of conjugated double-bonds to transfer a charge over the chain thereby providing their own electrical conductivity in the organic coatings. The charge from the chain in combination with the iron substrate generates electrons to the formation of passivation products on the surface of paint film. This paper is focused on combination of zinc ferrite with conductive polymer and using of synergic effect of these two components. The organic coatings were formulated from hematite and specularite on pigments concentration line 5, 10, 20 and 25 wt.% for better recognizing of the effectiveness of zinc ferrite component. The content of the conductive polymer was consistently set at 3 wt.% in each organic coating. A solvent-based epoxy-ester resin was used as a binder. The physico-mechanical and corrosion tests were performed for all samples. The corrosion signs were evaluated on the surface of coating and also on the surface of metal substrate. In the end, the efficiency was compared alone zinc ferrite and alone polymers and also their combinations.
Aluminium alloy AA5083 is prone to intergranular corrosion in marine environments. In an attempt to reduce the intergranular corrosion, AA5083 was subjected to friction stir processing (FSP). The FSP experimental trials were conducted as per face-centered central composite design with three levels of variation in FSP process parameters viz. tool rotation speed (TRS), tool traverse speed (TTS) and tool shoulder diameter (SD). Intergranular corrosion susceptibility of the processed specimens was assessed by performing nitric acid mass loss test. The mass loss of the specimens was correlated with the intergranular corrosion susceptibility as per the standard ASTM G67-13. The experimental results indicate that FSP had significantly reduced the intergranular corrosion susceptibility of the AA5083 alloy. Soft computing techniques namely Artificial Neural Network, Mamdani Fuzzy system, and Sugeno Fuzzy system were used to predict the intergranular corrosion (IGC) susceptibility (mass loss) of the friction stir processed specimens. Among the developed models, Sugeno fuzzy system displayed minimum percentage error in prediction. So Sugeno fuzzy system was used to analyze the effect of friction stir processing process parameters on the IGC of the processed specimens. The results suggest that stir processing of AA5083 at a TRS of 1300 rpm, TTS of 60 mm/min and SD of 21 mm would make the alloy least susceptible to intergranular corrosion.
Kamil Borko, F. Pastorek, Jacková M. Neslušan, S. Fintová and B. Hadzima
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.
F. T. Kubatík, J. Stoulil, F. Lukáč, K. Stehlíková and P. Slepička
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 (Rcν) of plasma-sprayed coatings of aluminium and AlCr6Fe2 alloy, compared with uncoated AZ91 in borate buffer with pH 9.1.
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.
M. Polutrenko, P. Maruschak, A. Tymoshenko and A. Sorochak
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.
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.
S. Panin, I. Vlasov, D. Dudina, V. Ulyanitsky, R. Stankevich, I. Batraev, P. Maruschak and M. Landová
The structure and mechanical properties of the coatings formed by reactive detonation spraying of titanium in a wide range of spraying conditions were studied. The variable deposition parameters were the nature of the carrier gas, the spraying distance, the O2/C2H2 ratio, and the volume of the explosive mixture. The phase composition of the coatings and the influence of the spraying parameters on the mechanical properties of the coatings were investigated. In addition, nanohardness of the individual phases contained the coatings was evaluated. It was found that the composition of the strengthening phases in the coatings depends on the O2/C2H2 ratio and the nature of the carrier gas. Detonation spraying conditions ensuring the formation of composite coatings with a set of improved mechanical properties are discussed.
High entropy alloys (HEAs) have been in focus of scientist for past few years owing to their predicted scratch, corrosion and temperature resistance and also to interesting magnetic properties. They are usually prepared by arc melting of at least 5 pure elements. This article deals with electrodeposition of such five-element alloy from water bath, which have not been yet reported. The HEA coating consisting of Fe, Co, Ni, Mn and Mo or Zn was successfully electrodeposited on steel, copper and other metallic substrates. Substrates were polished and treated by sonication in acetone prior to electrodeposition. Obtained thin layers were documented by optical microscopy and SEM techniques. Their exact composition was determined by EDS and XRF analysis. Scratch and accelerated corrosion tests were performed to asses their resistance properties. Electrochemical properties were determined by measurements of polarization curves.
D. Kajánek, B. Hadzima, F. Pastorek and M. Neslušan Jacková
The contribution is focused on the preparation of coating based on the dicalcium phosphate-dihydrate (DCPD) on the surface of ZW3 magnesium alloy. For the preparation of the coating a cathodic electrodeposition technique called Large Amplitude Sinusoidal Voltammetry (LASV) was used. The DCPD layer was prepared at the temperature of 22 ± 2 °C in electrolyte composed of 0.1M Ca(NO3).4H2O, 0.06 M NH4H2PO4 and H2O2. Electrochemical characteristics were evaluated by electrochemical impedance spectroscopy (EIS) in 0.1M NaCl solution. The obtained data in form of Nyquist plots were analysed by the equivalent circuit method. It is clear from the measured values of polarization resistance Rp that dicalcium phosphate-dihydrate (DCPD) layer prepared by LASV electro-deposition technique improved corrosion resistance of ZW3 alloy in the chosen environment.