The paper presents the results of the pitting resistance investigations of selected stainless steels in the chloride environment and the simultaneous impact of erosive factors using the cyclic polarization technique. Additionally, using electrochemical techniques, ie: electrochemical impedance spectroscopy (EIS) and measurement of corrosion potential, the behavior of the passive layer of selected stainless steels in the environment of chlorides and erosion was examined. On the basis of the obtained results, the resistance of stainless steels 1.4301 and 1.4404 was found, both on the effect of chloride ions and erosive factors in the studied systems. Both tested steels are susceptible to pitting corrosion. It was found that a good measure of erosive impact on stainless steel is both impedance spectrum analysis and continuous monitoring of the corrosion potential of steel.

The objective of the presented paper is to investigate the performance of concrete containing volcanic scoria as cement replacement after 7, 28, 90, and 180 days curing. Five performance indicators have been studied. Compressive strength, water permeability, porosity, chloride penetrability, and reinforcement corrosion resistance have all been evaluated. Concrete specimens were produced with replacement levels ranging from 10 to 35%. Test results revealed that curing time had a large influence on all the examined performance indicators of scoria-based concrete. Water permeability, porosity, and chloride penetrability of scoria-based concrete mixes were much lower than that of plain concrete. Concretes produced with scoria-based binders also decelerated rebar corrosion, particularly after longer curing times. Furthermore, an estimation equation has been developed by the authors to predict the studied performance indicators, focusing on the curing time and the replacement level of volcanic scoria. SEM/EDX analysis has been reported as well.

The present study examines some durability aspects of ambient cured bottom ash geopolymer concrete (BA GPC) due to accelerated corrosion, sorptivity, and water absorption. The bottom ash geopolymer concrete was prepared with sodium based alkaline activators under ambient curing temperatures. The sodium hydroxide used concentration was 8M. The performance of BA GPC was compared with conventional concrete. The test results indicate that BA GPC developes a strong passive layer against chloride ion diffusion and provides better protection against corrosion. Both the initial and final rates of water absorption of BA GPC were about two times less than those of conventional concrete. The BA GPC significantly enhanced performance over equivalent grade conventional concrete (CC).

Optical Coherence Tomography (OCT) is one of the most rapidly advancing techniques. This method is capable of non-contact and non-destructive investigation of the inner structure of a broad range of materials. Compared with other methods which belong to the NDE/NDT group (Non-Destructive Evaluation/Non-Destructive Testing methods), OCT is capable of a broad range of scattering material structure visualization. Such a non-invasive and versatile method is very demanded by the industry. The authors applied the OCT method to examine the corrosion process in metal samples coated by polymer films. The main aim of the research was the evaluation of the anti-corrosion protective coatings using the OCT method. The tested samples were exposed to a harsh environment. The OCT measurements have been taken at different stages of the samples degradation. The research and tests results have been presented, as well as a brief discussion has been carried out.

This paper deals with the evaluation of the corrosion resistance of the Al-Si alloys alloyed with the different amount of antimony.

Specifically it goes about the alloy AlSi7Mg0,3 which is antimony alloyed in the concentrations 0; 0,001; 0,005; 0,01 a 0,05 wt. % of

antimony. The introduction of the paper is dedicated to the theory of the aluminium alloys corrosion resistance, testing and evaluation of

the corrosion resistance. The influence of the antimony to the Al-Si alloys properties is described further in the introduction. The

experimental part describes the experimental samples which were prepared for the experiment and further they were exposed to the

loading in the atmospheric conditions for a period of the 3 months. The experimental samples were evaluated macroscopically and

microscopically. The results of the experiment were documented and the conclusions in terms of the antimony impact to the corrosion

resistance of the Al-Si alloy were concluded. There was compared the corrosion resistance of the Al-Si alloy antimony alloyed (with the

different antimony content) with the results of the Al-Si alloy without the alloying after the corrosion load in the atmospheric conditions in

the experiment.

In the paper the results and analysis of corrosion tests were presented for low-alloyed cast steel in as-cast state and after heat treatment

operations. Such alloys are applied for heavy loaded parts manufacturing, especially for mining industry. The corrosion test were

performed in conditions of high salinity, similar to those occurring during the coal mining. The results have shown, that small changes in

chemical composition and the heat treatment influence significantly the corrosion behaviour of studied low-alloyed cast steels.

This paper presents an analysis of the corrosion hazard in the burner belt area of waterwalls in pulverised fuel (PF) boilers that results from low-NOx combustion. Temperature distributions along the waterwall tubes in subcritical (denoted as SUB) and supercritical (SUP) boilers were calculated and compared. Two hypothetical distributions of CO concentrations were assumed in the near-wall layer of the flue gas in the boiler furnace, and the kinetics of the waterwall corrosion were analysed as a function of the local temperature of the tubes. The predicted rate of corrosion of the boiler furnace waterwalls in the supercritical boilers was compared with that of in the subcritical boilers.

In this article the structural and mechanical properties of grain refinement of Cu-Sn alloys with tin content of 10%, 15% and 20% using the KOBO method have been presented. The direct extrusion by KOBO (name from the combination of the first two letters of the names of its inventors – A. Korbel and W. Bochniak) method employs, during the course of the whole process, a phenomenon of permanent change of strain travel, realized by a periodical, two-sided, plastic metal torsion. Moreover the aim of this work was to study corrosion resistance. The microstructure investigations were performed using an optical microscope Olimpus GX71, a scanning electron microscope (SEM) and a scanning transmission electron microscope (STEM). The mechanical properties were determined with INSTRON 4505/5500 machine. Corrosion tests were performed using «Autolab» set – potentiostat/galvanostat from EcoChemie B.V. with GPES software ver. 4.9. The obtained results showed possibility of KOBO deformation of Cu-Sn casting alloys. KOBO processing contributed to the refinement of grains and improved mechanical properties of the alloys. The addition of tin significantly improved the hardness. Meanwhile, with the increase of tin content the tensile strength and yield strength of alloys decrease gradually. Ductility is controlled by eutectoid composition and especially δ phase, because they initiate nucleation of void at the particle/matrix interface. No significant differences in the corrosion resistance between cast and KOBO processed materials were found.

The Ti15Mo alloy has been studied towards long-term corrosion performance in saline solution at 37°C using electrochemical impedance spectroscopy. The physical and chemical characterization of the material were also investigated. The as-received Ti15Mo alloy exhibits a single β-phase structure. The thickness of single-layer structured oxide presented on its surface is ~4 nm. Impedance measurements revealed that the Ti15Mo alloy is characterized by spontaneous passivation in the solution containing chloride ions and formation of a double-layer structured oxide composed of a dense interlayer being the barrier layer against corrosion and porous outer layer. The thickness of this oxide layer, estimated based on the impedance data increases up to ~6 nm during 78 days of exposure. The observed fall in value of the log|Z|f = 0.01 Hz indicates a decrease in pitting corrosion resistance of Ti15Mo alloy in saline solution along with the immersion time. The detailed EIS study on the kinetics and mechanism of corrosion process and the capacitive behavior of the Ti15Mo electrode | passive layer | saline solution system was based on the concept of equivalent electrical circuit with respect to the physical meaning of the applied circuit elements. Potentiodynamic studies up to 9 V vs. SCE and SEM analysis show no presence of pitting corrosion what indicates that the Ti15Mo alloy is promising biomaterial to long-term medical applications.

The paper discusses the results of investigations of material, tribological and anti-corrosion properties of hybrid coatings of the Cr/CrN type, consisting of chromium and chromium nitride, formed on the surface of alloy tool steel by the Arc-PVD method. Investigations of the morphology and microstructure of hybrid coatings, as well as of their phase composition were carried out. The studies on mechanical properties included tests on hardness and Young’s modulus using the nanoindentation method. Tests on adhesion were conducted using the scratch-test method. Tribological properties of the obtained coatings were evaluated by the pin-on-disc method. Resistance to corrosion was determined by electrochemical methods. It was shown that hybrid coatings of the Cr/CrN type are characterized by good adhesion to the substrate and very good tribological properties, as well as by very good resistance to corrosion in a solution containing chlorine ions.

Corrosion is a main problem for longtime exploration of heat exchangers in automotive industry. Proper selection of accelerated corrosion test for newly developed material is a key aspect for aluminum industry. The selection of material based on corrosion test includes test duration, chemical spray composition, temperature and number of cycles. The paper present comparison of old and newly developed accelerated corrosion tests for testing automotive heat exchanger. The accelerated test results are comprised with heat exchanger taken from market after life cycle.

This article presents the results of a numerical analysis of the road acoustic screen deterioration. Due to the fact that road noise barriers are located in an environment of very high corrosivity, the problem is the rusting of the metal cladding of component panels. The presented case study was, therefore, verified to fulfill the requirements presented in the Eurocode EN 1794-1. Static analysis for wind load and dynamic analysis for the load induced from vehicles was carried out. The analysis presented in the article proved the design errors and their contribution to the formation of severe corrosion, as well as demonstrating the importance of dynamic analysis in the design of acoustic screens.

The Ca50Mg20Zn12Cu18 was assessed with different methods in order to characterize its basic characteristics, and to determine whether the amorphous alloy of such composition would be applicable as an implant material. The XRD analysis was conducted to conclude the structure of the initial material. The Ca50Mg20Zn12Cu18 ingot sample demonstrates crystalline structure containing two main intermetallic phases, however as-cast plates show features of an amorphous material, revealing the characteristic amorphous halo on the x-ray patterns. It was confirmed by the scanning electron microscopy method and fracture images revealing chevron pattern morphology with shell type fracture. Corrosion resistance, was studied using the potentiostatic analysis. The amorphous samples show higher resistance than the crystalline one. Post corrosion surface of the Ca50Mg20Zn12Cu18 alloy exhibits high concentration of magnesium and calcium hydroxides, forming the globular structures in large aggregates of spherical units.

The paper presents the research results of the solenoid housing made of the Zn4Al1Cu alloy that was destroyed as a result of corrosion.

Surface of the tested part showed macroscopically the features typical for white corrosion, and the resulting corrosion changes led to a

disturbance of the alloy cohesion. The research performed have shown that the tested solenoid valve has intergranular corrosion as a

reaction of the environment containing road salt. The corrosion was initiated in the areas of the alfa phase existence appearing in the

eutectic areas which propagated over dendritic areas of the alloy. Initiation of the corrosion followed as a result of the galvanic effect of

the alfa phase reach in aluminium showing higher electrochemical potential, in contact with the eta phase reach in zinc. The impact of the

phase reach in lead present in the microstructure on the corrosion processes run was not found.

The main goal of this work is to show the new approach to determining safety technological levels (SLs) in terms of water quality and its chemical stability, as well as issues of water corrosion properties in water distribution systems (WDSs), due to the fact that water supply pipes are prone to corrosion. In the paper the methodology of determining the risk associated with threat to technical infrastructure was considered. The concept was studied on the basis of real operational data from the water treatment plant. The probability of exceeding the individual parameters for WTPI is slightly larger than for WTPII, which means that this water treatment process may cause lack of chemical stability in the water supply network. Operators should anticipate in the process of designing water distribution system, using proper materials, as to ensure an adequate level of safety from the water source to the water recipient. It should be noted that it is necessary to adjust the material of internal installation of water supply networks to the parameters of the water. At present, there are no correlations between the designing step and water parameters. It was concluded that to protect the water supply infrastructure, which belongs to critical infrastructure, water company should put more emphasis on distribution of stable water that has not potentially corrosion properties. Some suggestions were made for the protection of WDS and to ensure safety of system functioning and long-term usability of water pipes.

The paper deals with the impact of co-firing biomass with coal in boilers on the dew point of the flue gas. Co-firing of biomass may have twofold implications on corrosion and fouling, which are the processes that determine the lowest acceptable flue gas outlet temperature and as a result, boiler efficiency. Both phenomena may be reduced by co-firing of usually low sulphur biomasses or enhanced due to increased moisture content of biomass leading to increased water dew point. The present study concerns the problem of low-temperature corrosion in utility boilers. The paper gives (in the form of diagrams and equations) a relationship between water dew point and moisture content of fuel mixture when co-firing coal and various biomasses. The regression analysis shows that despite significant differences in the characteristics of coals and these of additional fuels, which are planned for co-firing in large-scale power boilers, the water dew point can be described by a function given with the accuracy, which shall be satisfactory for engineering purposes. The discussion of the properties of biofuels indicates that the acid dew point surplus over the water dew point (Δtr = tr - twr) is not likely to exceed 10 K when co-firing biomass. The concluding remarks give recommendations for the appropriate operation of boilers in order to reduce risks associated with biomass co-combustion.

The influence of the electrode geometry on the microstructure and corrosion behaviour of Co-Mo nano-crystalline coatings elaborated by electrodeposition is studied. The corrosion behaviour was determined in the Ringer’s solution at 25°C. Electrodeposition mechanisms are also discussed as a function of the electrode geometry. The electrode geometry was found to affect the growth rate and, under certain conditions, the microstructure (existence of channels and pores). It does not have influence on the corrosion behaviour.

The paper presents the results of studies of hybrid composite layers Ni/Al2O3/Cgraphite produced by the electrodeposition method. Three variants of hybrid composite layers were prepared in electrolyte solutions with the same amounts of each dispersion phases which were equal to 0.25; 0.50 and 0.75 g/dm3. The structure of Ni/Al2O3/Cgraphite layers as well as the Al2O3 and graphite powders, which were used as dispersion phases was investigated. The results of morphology and surface topography of produced layers are presented. The modulus of elasticity and microhardness of the material of produced layers were determined by DSI method. Tribological and corrosion resistance tests of produced layers were carried out. Realized studies have shown that the material of the produced layers is characterized by a nanocrystalline structure. Incorporation of dispersion phases into the nickiel matrix increases the degree of surface development of layers. Ni/Al2O3/Cgraphite layers are characterized by high hardness and abrasion resistance by friction, furthermore, they provide good corrosion protection for the substrate material.