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„Ochrona przed Korozją” (Corrosion Protection) No 04/2017

View cover and table of contents (in Polish and English) (pdf)


DOI: 10.15199/40.2017.4.1

Determination of corrosion rate of porous, liquid permeable materials on the example of hydride powder composite



Czestochowa University of Technology, Department of Chemistry

Corrosion rate of permeable porous materials can be determined from relation of given specimen extensive property versus exposure time in working fluid. Such an attempt allows to evaluate the corrosion process rate irrespectively of uncontrolled changes of sample effective surface. The changes of extensive physical parameter of porous hydride material is discussed on the example of the fade of specific hydride capacity (Q)

for La(Ni,Co)5 type powder composite electrode. The advantageous role of active material encapsulation with Ni-P coatings is additionally pointed out. The actual capacity changes of the electrode are presented versus charge/discharge cycle number (N) in two kinetic variants: Q = f (N) and ln Q = f (N). In both cases correlation is very good, with determination coefficients ≈ 0.96. The slopes of rectilinear segments of these relationships correspond to corrosion degradation rate constants of nulland first order reactions, respectively. The integral kinetic equations have been used to determine corrosion rates as well as half capacity decay cycles of the porous hydride material.

Keywords: permeable material, porosity, degradation kinetics, corrosion rate, capacity fade


Vol. 60, nr 4

s. 79-83

Ref. 34



DOI: 10.15199/40.2017.4.2

Electrochemical impedance spectroscopy of Ni–Mo alloy coatings in 0.5 M NaCl solution


Department of Inorganic Chemistry, Wrocław University of Economics


Department of Advanced Material Technologies, Faculty of Chemistry, Wrocław University of Technology


Department of Inorganic Chemistry, Wrocław University of Economics


Department of Advanced Material Technologies, Faculty of Chemistry, Wrocław University of Technology

The corrosion resistance of Ni–Mo (11÷32 wt% Mo) alloy coatings during 72 h exposure in 0.5 mol·dm−3 solution of NaCl was investigated by means of EIS method. The highest corrosion resistance (charge transfer

resistance >12 kΩ·cm2) among all investigated coatings was measured for Ni–Mo coatings with higher molybdenum content (21÷32 wt%). However, after 48-60 h of immersion, visible micro cracks appeared in Ni–28 wt% Mo and Ni–32 wt% Mo alloy coatings, probably due to the significant internal stresses. This phenomenon was observed especially for Ni–32 wt% Mo coating, and it was accompanied by an abrupt decrease in a charge transfer resistance from 8.7 to 2.7 kΩ·cm2 after 5 and 24 h, respectively. According to EIS results, coating containing 21 wt% Mo offers the best protective properties towards steel substrate. This may be associated with the existence of a compact, tight and very thin passive layer which does not undergo damage during exposure.

Keywords: Ni–Mo coating; passive layer; electroplating, SEM, EIS


Vol. 60, nr 4

s. 84-87

Ref. 11



DOI: 10.15199/40.2017.4.3

Corrosion behavior of LaNi4.6Zn0.4-xSnx (x = 0÷0.4) alloys in alkaline solutions with chloride ions


Institute of Chemistry, Environmental Protection and Biotechnology, Jan Dlugosz University of Czestochowa

In the study, electrochemical corrosion of LaNi4.6Zn0.4-xSnx (x = 0÷0.4) type alloys in a strongly alkaline environment has been characterized. The influence of the presence of Cl− ions in KOH solutions on the corrosion behavior of these materials has been studied. Using the potentiokinetic method, durability of passive layers formed on LaNi4.6Zn0.4-xSnx alloys in 1M and 6M KOH solutions with chloride ions has been evaluated. All the examined LaNi4.6Zn0.4-xSnx alloys passivated efficiently in 1 M and 6 M KOH solutions. Material composition and concentration of KOH solution has significant effect on the protective properties of passive layers formed on LaNi4.6Zn0.4-xSnx type alloys. Passive layers formed on the alloys donated solely with zinc (LaNi4.6Zn0.4), in both 1 M and 6 M KOH solutions are more resistant to chloride ions with 0.3÷1.0 M concentration, whereas the addition of chloride ions to 1 M KOH solutions leads to a local degradation of the passive layer formed on the alloys with tin (LaNi4.6Zn0.2Sn0.2 and LaNi4.6Sn0.4).

Keywords: LaNi4.6Zn0.4-xSnx -type alloys, polarization curves, pitting corrosion


Vol. 60, nr 4

s. 88-90

Ref.  10



DOI: 10.15199/40.2017.4.4

Corrosion resistance of nitrocarburized layers produced on Ti6Al7Nb titanium alloy




Faculty of Materials Science and Engineering, Warsaw University of Technology

Two-phase Ti6Al4V titanium alloy, due to its vanadium content and carcinogenic properties exposed during metallosis, is slowly being replaced by so-called vanadium-free titanium alloys, e.g. Ti6Al7Nb, demonstrating a similar level of durability. Comparative studies have been carried out on the corrosion resistance of Ti6Al7Nb alloy before and after glow-discharge nitrocarburizing carried out at cathodic potential and at plasma potential, i.e. in a process incorporating an active screen. Corrosion resistance tests of nitrocarburized layers produced on Ti6Al7Nb alloy were carried out via electrochemical impedance spectroscopy (EIS) and the potentiodynamic method in Ringer’s solution at 37°C. The results also included information on the microstructure of the obtained layers and surface roughness measurement data. The study showed that the microstructure and corrosion resistance of the surface layers obtained differed depending on the nitrocarburizing process employed.

Keywords: nitrocarburized layers, titanium alloys, corrosion resistance, Ringer’s solution


Vol. 60, nr 4

s. 91-95

Ref. 20



DOI: 10.15199/40.2017.4.5

Analysis of the hydrogen concentration in the products made of steel grade 41Cr4


Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, Katowice


BELOS-PLP S.A., Bielsko-Biała



Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, Katowice


Academy of Technology and Humanities, Faculty of Materials, Civil and Environmental Engineering, Bielsko-Biała

The results of the hydrogen concentration measurements in the hot-dip galvanized products, made of steel grade 41Cr4 have been presented in the paper. The analysis was performed using an elemental analyser LECO ONH836. The research was divided into two stages. In the first stage the hydrogen concentration was measured in samples taken from the threaded products, galvanized in 2012. In the second stage, the hydrogen

concentration at different stages of production was determined. The material as delivered, after rolling, shot blasting, shot blasting and etching and galvanizing was analysed. Different ways of the materials preparation to HDG (Hot-Dip Galvanizing) were used. On the basis of the results, it was found that, hydrogen content is strictly dependent on the specific sampling point. The presence of the Zn coating in the sample affects the accuracy of the measurement of the hydrogen content. Samples containing Zn coating have higher hydrogen content than samples without Zn coating. Hydrogen content in steel did not exceed 1 ppm in each analysed case. Hydrogen content in samples taken from threaded sections is higher than in samples taken from nonthreaded sections. Measuring only hydrogen concentration is not a reliable test for the formulation of conclusions about hydrogen embrittlement or hydridation effect.

Keywords: measurement of the hydrogen concentration, zinc coating, hot-dip zinc galvanizing


Vol. 60, nr 4

s. 96-101

Ref. 10



DOI: 10.15199/40.2017.4.6

Effect of surface modification of the LaNi4.5Co0.5 powder with thin silicon film on the electrochemical performance of composite hydride electrode



Department of Chemistry, Czestochowa University of Technology

Surface of LaNi4.5Co0.5 hydride alloy powder has been modified by magnetron sputtering using silicon target. The process of composite electrodes cycling at −0.5 C/+0.5 C charge/discharge rates has been carried

out in 6 M KOH throughout 40 cycles at ambient temperature. Deposition of thin Si films on the active powder improves its hydrogenation kinetics: the exchange current densities of H2O/H2 system are 5÷10% greater on the modified electrode. After some initial cycles, logarithm of discharge capacity linearly decreases with the number of cycles. For powders modified with silicon films, the slope of rectilinear segment of log Qdisch = f(N) relationship is 2.5 times lower than that for unmodified powder. The presence of Si film evidently decreases the electrode corrosion rate and prolongs the electrode half decay cycle number.

Keywords: intermetallic alloy, corrosion rate, magnetron sputtering, charge/discharge, Si thin films


Vol. 60, nr 4

s. 102-104

Ref. 24



DOI: 10.15199/40.2017.4.7

The influence of activated sludge wastewater treatment plant on the distribution of pores in mortars CEM I



PK Cracow University of Technology, Faculty of Civil Engineering Chair

of Building Materials Technology and Structure Protection

This paper is an attempt at analysing the effect of microorganisms contained in activated sludge at sewage treatment plants on the structure of porosity of unmodified and polymer modified cement-based materials. The examination used CEM I Portland cement mortar. In the course of the investigation results were obtained indicating changes in the density as well as changes in the total, closed and open porosity. Microbiological corrosion products are probably located within pores with dimensions in the range of 10 nm to 5000 nm. Redistribution of pores takes place and a clear distinguishing of pores with diameters of 10÷100 nm. It is probably in the first stage that the process of unsealing of the structure takes place, and only afterwards it is followed by formation of corrosion products and deposition thereof in the pores of the material.

Keywords: activated sludge; sewage treatment plants, CEM I mortars, acrylic resin, polisiloxane resin, polycarboxylate resin


Vol. 60, nr 4

s. 105-109

Ref. 23



DOI: 10.15199/40.2017.4.8

Effect of water solution of chloride salts on ceramic bricks drying


Cracow University of Technology, Faculty of Civil Engineering

The article presents the results of a multi-faceted research on the impact of chloride salts on the texture of bricks, and the effects of these interactions. The change of pore structure was determined using mercury intrusion porosimetry. The dominant category pores for process of accumulation of salts was determine too. In addition, observations of the microstructure of bricks exposed in NaCl, KCl and MgCl2 solution were made. For comparison, the observation of the microstructure of samples taken from the bricks existing facilities exposed in real sea water are presented, too. The presence of chloride salts also has a significant impact on the process of drying ceramic masonry but the studies have shown no significant differences in drying bricks, depending on the type of cation. The article results systematize and organize information on the durability of bricks in an environment of chloride salts.

Keywords: chloride salts, ceramic bricks, drying, microstructure, pore structure


Vol. 60, nr 4

s. 110-113

Ref. 7



DOI: 10.15199/40.2017.4.9

Corrosion resistance of anodized Zn-Co alloy coatings determined by NSS method






Wydział Chemiczny, Politechnika Śląska, Gliwice

Results of investigations on corrosion resistance of electrodeposited Zn- Co alloy coatings oxidized anodically in methanolic solution of sodium hydroxide have been presented in the paper. The accelerated corrosion test in a salt chamber by NSS (Neutral Salt Spray) method, under conditions according to the PN-EN ISO 9227:2007 standard was carried out in the framework of the work. The progress of the corrosion processes was determined by visual observations as well as quantitatively. On the basis of the realized studies it was found that anodic treatment of the Zn- Co coatings in the used bath causes formation of conversion coatings which significantly improve their anticorrosion properties. The sample oxidized up to 50 V achievement was characterized by the best corrosion resistance among all of the investigated samples.

Keywords: zinc-cobalt coating, Zn – Co alloy, salt chamber, NSS test


Vol. 60, nr 4

s. 114-117

Ref.  15



DOI: 10.15199/40.2017.4.10

Stripping of copper coatings from steel elements subjected to thermochemical treatment






Silesian University of Technology, Faculty of Chemistry, Gliwice


J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków


Pratt & Whitney, Kalisz

The necessity of masking part of the surface of steel elements during processing by the deposition of copper layer occurs frequently in the industry. Most frequently these layers are removed then by etching in chromic(VI) acid solutions, what brings serious environmental problems. The possibility of replacing chromic acid solutions with the solutions containing hydrogen peroxide (H2O2) as an oxidizer and copper complexing agents was analyzed in the present paper. Basing on the analysis of the physicochemical data, ethylenediaminetetraacetic acid (EDTA) was selected as a potential complexing agent. It was showed experimentally that solutions containing EDTA, ammonia, and H2O2 are well suited for the removal of copper from the surface of steel. In the case of those solutions the rate of etching of copper is several times higher than in the case of chromic(VI) acid solutions, at the same time they do not cause corrosion of steel.

Keywords: copper coatings on steel, stripping of copper coatings on steel, copper etching


Vol. 60, nr 4

s. 118-124

Ref. 5




DOI: 10.15199/40.2017.4.11

 Corrosion management of steel underground objects in Poland and modern development of cathodic protection technology



The aim of corrosion management is ensuring of functionality of technical objects in accordance with their designation, the fulfilled function and the adopted operating time. In the article distinct changes have been critically presented in this field in the past 50 years, which occurred in the Polish economy with reference to metal underground objects. They are connected in a great extent with development of cathodic protection technology, but also with the choice and application of new coating materials. During these years earlier adopted canons of anti-corrosion protection technology changed of such objects as telecommunication cable armatures, pipelines or underground tanks. Also, new corrosion hazards appeared on their surfaces, e.g. caused by induced alternate currents from high voltage overhead power lines.

Keywords: corrosion management, underground objects, cathodic protection


Vol. 60, nr 4

s. 125-128

Ref. 14