International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This paper examines corrosion protection techniques for aluminum alloys, focusing on traditional and innovative surface treatment methods. Aluminum alloys are applicable in many industries due to their advantages derived from the good combination of chemical, physical, and mechanical properties. However, they are susceptible to various forms of corrosion, which can critically compromise the structure of the component and lead to damage that does not ensure safe operation. Coatings are necessary for the durability and effective protection of aluminum and its alloys from corrosion, ensuring safe and long-term operation of components in aggressive environments.

Steel wire rope was breaked in exploratory conditions i.e. during hoisting the load. The requirement of the purchaser of the investigations was to find a reason which caused breaking the steel rope. In other words to check fitness for purpose of the used steel wire rope. Because of that all necessary investigations to solve this problem were performed. As first, quality of delivered rope was checked. More concretely it was checked chemical composition of the base material (steel strands and wires). Besides, quality of the base material i.e. presence of non-metallic inclusions, microstructure, segregation and decarburation of the rope wires was done. This investigation showed that base material is high carbon steel. Its quality fulfill necessary requirement. Therefore, the next step was to make failure analysis of the rope after long period of exploitation. These investigations contain visual inspection of the rope, metallographic investigations, fractographic analysis and tensile test.
Visual inspection was performed according ISO 4309 and ASME B30.30. Standards [1-3]. This inspection was performed to all segments of the rope. To perform visual inspection segments were unwinded and separately tested. It was found that the most serious damaging was detected near the breaking point of the rope.
Performed investigations clear confirmed that wear of the rope is the most often detected type of failure. Besides corrosion of the rope was detected at many locations too. Metallographic investigation detected the wear damage too. Scaning electron microscope (SEM) confirmed that shear and fatigue are the most often found types of fracture in the rope wires.
It was concluded from the investigation to too that lubrication of the rope is different at different locations. It means that at some position there is no lubrication.
It is obvious that defects (failures) which caused breaking of the rope appeared in the rope during exploitation.
Metallographic investigations of the wires and visual control of the ropes segments and strands confirmed that all defects in the ropes are results of improper installation, manipulation and handling of the rope.
Nominal value of the load, which can be hoisted by steel rope, became lower during exploitation. More concretely remained load, which can be hoisted, is in relationship 5:1 with nominal load [4-6]. So if higher load was hoisted, the rope will be breaked as it happened in our case.

The object of research – the natural glycoalkaloid solanine as a possible inhibitor of acid corrosion of steel St3. Modern data on the structure and physico-chemical properties of solanine, such as amphiphilicity, surface activity, basicity, characteristic of modern organic corrosion inhibitors, are presented. The basic concepts are defined: basic nitrogen, solanine amphiphilicity, mass and volume corrosion indicators, corrosion inhibitor, degree of protection, corrosion inhibition coefficient. The literature data on the corrosive activity of lactic acid (MC) are presented and characterized.

The influence of the vanadium, niobium and boron addition on properties of high-chromium white cast iron alloys for grinding balls is investigated in this paper. These alloying elements were individually added to the high-chromium white cast iron alloys with monitoring of changes in microstructure, corrosion rate, and mechanical properties in the as-cast conditions. The microstructure in all tested alloys consists of primary austenite dendrites and eutectic colonies, which consist of M7C3 carbides and austenite. The addition of V, Nb or B affects, to a greater or lesser extent, the size, morphology and volume fraction of both primary austenite dendrites and eutectic colonies. Samples of iron alloyed with vanadium and boron have a much finer structure than unmodified (base) alloy and niobium alloyed iron sample. Vanadium affects the decrease in the volume fraction of the primary austenitic phase, and the increase in the volume fraction of eutectic colonies, and thus the eutectic carbide phase in hypoeutectic alloys of high-chromium iron. The tested alloys have a comparable values of average hardness in the cross section of cast balls, as well as compressive yield strength, noting that the addition of vanadium increases the hardness, while boron addition increases the compressive yield stress. The single addition of all of three tested alloying elements shifts the corrosion potentials (and Tafel curves) of modified high-chromium white irons toward less negative values. The most favorable values of mechanical and corrosion properties were measured for the iron modified with 0.021 % of boron.

The object of the study is the part of the galvanized steel pipe (about 1-meter-long) supplied by the customers, which was used to supply hot water inside the residential building and which has corroded during exploitation of 5 years. To clarify the situation, quality of surface coating and microstructure of the obtained galvanized steel pipe was analysed. Electrical stray currents of the pipeline installed in the building were measured. The sample of the hot water was taken and analysed at the certificated laboratory.
The aim of the investigation was to determine the possible causes of the hot water supply pipe corrosion during sufficiently short time of exploitation.

Mechanical wear, corrosion and erosion of the structural materials in machines and apparatus are destructive processes which cause worsening of their basic operational characteristics throughout their life cycle. As a result, the technological equipment undergoes loss of efficiency and reliability. It becomes unsafe from hygienic point of view. The expenses needed for its maintenance in crease significantly as the time passes. Its economical efficiency decreases as well. Materials which are in direct contact with food products can also transmit metallic ions or low molecular compounds to the processed food products – a process which is known as “migration”. Thin Layer Activation (also known as Surface Layer Activation) is an unique, efficient and innovative radiation based method used for conducting of comprehensive studies on surface degradation of materials. It allows real-time measurements of wear intensities with exceptionally high sensitivity within the scope of several ηm/h (or μg/h). The article reviews the essential principles of the Thin Layer Activation Method (TLA Method), describes its applications, capabilities and advantages. Possible uses in food processing industry are assessed and potential benefits from its implementation are discussed. Technological equipment in food processing industry includes machines and apparatus for production and processing of food products and liquids, packaging equipment, sanitation equipment, equipment for refrigeration and maintaining of certain environmental conditions, transportation equipment and auxiliary tools and equipment.

Casing is an extremely important element in the process of drilling a well borehole, as they define the diameter of the well and, among many other tasks, protect it from collapsing. In order to ensure long-term successful performance of all tasks, it is necessary to appropriately dimension casing, which means that the appropriate inner and outer diameter should be selected with the appropriate material and its quality, with proper installation depth for each set of casing. Conventional casing made of steel is most often used and this is still an ideal material for most wells. However, this material is prone to corrosion, which is a major problem on certain locations du ring the
production life of the well. Reduction and possibly elimination of corrosion on casing led the industry to explore financially viable composite materials, such as fiberglass, that could withstand expected stresses in well conditions with better corrosion resistance th an steel.

The influence of Zn on the corrosion behavior of amorphous and nanosized rapidly solidified aluminum alloys (Al75Cu17Mg8)100-xZnx (x = 0; 1; 3) at. % and their crystalline analogues was studied. Data were obtained for resistance of basic and rapidly solidified aluminum alloys (Al75Cu17Mg8)100-xZnx (x = 0; 1; 3) at. % to uniform corrosion. It has been found that increasing the percentage of zinc increases the corrosion rate of both base alloys and rapidly solidified ribbons with similar composition. Pitting and intergranular corrosion tests have been performed. The parameters affected area, pitting density and pitting size were evaluated. An XRD analysis of the separated corrosion products was performed. It was found that the chemical composition, and not the amorphous microstructure of the ribbons, was of leading importance for the course of the corrosion process in the studied rapidly solidified ribbons (Al75Cu17Mg8)100-xZnx and base alloys.

The corrosion of high purity MgO refractories from molten iron-rich OBM converter slag has been investigated by performing experiments in an electric laboratory furnace. Corrosion tests were conducted at 1600 – 1650oC for 1, 2 or 4 hours. Following lab experiments, the mineralogical phases of MgO refractories, slags and the intermediate infiltration zone were identified by SEM/EDS. It has been shown that Fe infiltrates and replaces Mg in MgO refractories, thus forming magnesiowustite ((Mg,Fe)O). The maximum depth of the slag infiltration zone was estimated to 1.31 mm in the laboratory test where slag was in contact with the refractory for 4 h, at 1650⁰ C Thermodynamic modeling of the slag and refractories equilibrium conducted with FactSage 7.0, confirmed the formation of magnesiowustite in the intermediate zone, with progressively higher substitution rate of Mg by Fe. This increasing substitution results in a decrease of the melting point of magnesiowustite, thus causing the collapse of the refractories even at temperatures lower than the operational temperature.

Solvay Sodi JSC, Devnya, Bulgaria, is the biggest calcite soda production plant in Europe. It is built in 1974 and it works in three-shift production regime up to present days. The exploitation environment is highly influenced by numerous factors, acting corrosively on main reinforced concrete structures – active atmospheric processes (in continental type moderate climate), sea water born chloride-aerosols, as well chemical attack caused by carbon dioxide and nitric acid, presented in the air in form of evaporation. The most reinforced concrete structures need urgent remedial measures to restore the load-bearing capacity of its components.
The “light soda” silos are reinforced concrete facilities (cylindrical shells) which repair has to be executed during continuous production process. The options for repair of these structures and restoration of their load bearing ability by specially designed innovative high-tech hybrid reinforced sprayed concrete, containing capillary crystalline admixture, are discussed in the report.
The in-situ tests and wide-range comparative studies are carried out, covering basic physical and mechanical structural characteristics of the proposed sprayed concrete for wet spraying and another one – based on proportioned dry ready mix.
The original scientific results concerning strength-deformation properties, phase composition and structure of hardened sprayed concrete, directly related to the durability in aggressive environment, are obtained by X-ray diffraction (XRD), differential thermal analysis (DTA), mercury porosimetry, low temperature gas adsorption (BET-method) and computer X-ray tomography.
The static and dynamic analysis of the structure is performed using the test results obtained and the fully specified engineering solution has been presented to restore the load-bearing capacity of the structures with a guaranteed service life of at least 50 years.

Solvay Sodi JSC, Devnya, Bulgaria, is the biggest calcite soda production plant in Europe. It is built in 1974 and it works in three-shift production regime up to present days. The exploitation environment is highly influenced by numerous factors, acting corrosively on main reinforced concrete structures – active atmospheric processes (in continental type moderate climate), sea water born chloride-aerosols, as well chemical attack caused by carbon dioxide and nitric acid, presented in the air in form of evaporation. The most reinforced concrete structures need urgent remedial measures to restore the load-bearing capacity of its components.
The “light soda” silos are reinforced concrete facilities (cylindrical shells) which repair has to be executed during continuous production process. The options for repair of these structures and restoration of their load bearing ability by specially designed innovative high-tech hybrid reinforced sprayed concrete, containing capillary crystalline admixture, are discussed in the report.
The in-situ tests and wide-range comparative studies are carried out, covering basic physical and mechanical structural characteristics of the proposed sprayed concrete for wet spraying and another one – based on proportioned dry ready mix.
The original scientific results concerning strength-deformation properties, phase composition and structure of hardened sprayed concrete, directly related to the durability in aggressive environment, are obtained by X-ray diffraction (XRD), differential thermal analysis (DTA), mercury porosimetry, low temperature gas adsorption (BET-method) and computer X-ray tomography.
The static and dynamic analysis of the structure is performed using the test results obtained and the fully specified engineering solution
has been presented to restore the load-bearing capacity of the structures with a guaranteed service life of at least 50 years.

The machinery in livestock farming works in a highly aggressive environment, increased ammonia content and high humidity. Anticorrosive protection of machines and equipment is widely used on the basis of lacquer materials. Their effectiveness is mainly determined by the selection of the varnish materials according to the type and degree of corrosion hazard.

Modern lacquer-based materials based on melamine, pentaftal, nitrocellulose, butyl methacrylate, chlorovinyl, epoxide and other resins are characterized by high protective properties and the possibility of renewal.