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

This paper deals with the study and evaluation of the utility properties of selected types of polymer powder coating systems applied to S235JR structural steel. The primary objective was to assess the influence of the coating system composition (combination of primer and topcoat versus individual layers) on its mechanical properties and corrosion resistance. The experimental part included surface preparation by blasting, electro kinetic application of four types of coating systems (Corro zinc 97, Corro coat MX, and Corro coat PE-F), followed by testing of roughness, thickness, adhesion, and bending resistance. Corrosion resistance was evaluated in a condensation chamber. The measurement results confirmed that the plasticity, measured by the bending angle, decreases with increasing coating thickness. The highest adhesion was exhibited by the combined coating system Corro zinc 97 + Corro coat MX. Corrosion tests demonstrated the crucial importance of the zinc-rich primer, which significantly slowed down the spread of sub-corrosion at the site of mechanical damage

Titanium alloys are essential in biomedicine due to their high specific strength and biocompatibility, with surface properties directly influencing the successful osseointegration of implants. In this study, surface texturing of an experimental titanium alloy was performed using an ultrafast femtosecond laser with varying pulse energies. Roughness and topography were analysed using optical profilometry and confocal laser scanning microscopy, while microhardness was measured by the Vickers method. The results show that a pulse energy of 2.1 µJ, with a wavelength of 1030 nm, pulse duration of 190 fs, and repetition rate of 1 MHz, constitutes the optimal laser process parameters for achieving the desired surface properties in engineering and biomedical applications.

The contribution is focused on the analysis of the surface roughness after applying the conversion layer using phosphating. In the experiment, uncoated deep-drawn steel DC 04 was used as the base material. During the application of the conversion layer, changes in surface roughness were studied with respect to the phosphating time, which was 3, 5 and 10 minutes. The achieved results provide information for other technological operations such as creating joints by gluing, where the correct anchoring of the glue is important for sufficient adhesion to the surface.

In the contribution, the surface quality of the steel substrate is analyzed from the point of view of its microgeometry as a set of quantities capturing the differences of individual surface changes. The subject of investigation are the surfaces of steel substrates, i.e. the base material, degreased surface, standard galvanized surface, surface after galvanizing and subsequent chromating, surface after phosphating and surface after phosphating and application of RAL coating.

This work presents a brief overview of the essence, principles and technological features of reactive electrospark processing (RESP), based on a simple, economical and ecological method – electrospark deposition (ESD), which avoids many of the disadvantages inherent in other existing methods. This treatment can optimize the physicochemical properties of the substrate surface and improve the structure, hardness and wear resistance. The application of RESP technology in surface modification of titanium alloys is considered. Research results, including those of the authors of this work, are presented, which demonstrate the possibilities of RESP for reducing
roughness and surface defects and for the synthesis of new phases and ultrafine structures that are not present in the electrode and substrate. The effect of RESP technology on the wear resistance of titanium and titanium alloys is shown. The main dependences of the quality and properties of the treated surfaces on the process parameters are identified, and ways to form reaction phases, to avoid and remove surface defects and to obtain “in-situ” new intermetallic and wear-resistant compounds are presented. The possibilities and prospects for the use of RESP to improve the surface characteristics and properties of titanium and its alloys are indicated.

The contribution is focused on the analysis of the roughness of metal surfaces after applying a conversion layer using phosphating. The types of basic materials is used in the experiment hot-dip galvanized microalloyed steel HX340LAD+Z. During the application of the conversion layer, changes in surface roughness were studied with respect to the phosphating time, which was 3, 5 and 10 minutes. The paper deals with the evaluation of the relationship between the individual roughnesses parameters of pre-treated surfaces using correlation analysis. Based on the measured roughness values on the surfaces, the standard of statistical significance of the correlation between the observed parameters was determined from them. The achieved results provide information for other technological operations such as the creation of adhesive joints, where the correct anchoring of the adhesive is important for load bearing capacity of joints.

This work discusses the properties of 3D titanium alloys with wear-resistant coatings of hard alloy electrodes based on WC-TiB2-B4C and solder mass of Co-Ni-Cr-B-Fe-Si-C, produced by reaction electrospark processing (RESP) at positive and negative polarity. Through profilometric, metallographic, XRD, SEM, EDS and tribological methods, the complex influence of polarity and pulse energy on the topography, composition, properties, and wear characteristics of the coated surfaces was investigated. The differences in the coatings obtained with the two polarities were identified. Coatings with similar roughness and thickness were obtained, which can be changed by changing the modes for RESP within the limits Ra =2.5÷5μm, δ= 8÷40μm, with microhardness 8 to 14 GPa and 2-4 times higher wear resistance than that of the substrate. At RESP with negative polarity and pulse energy up to 0.04 J, the coatings have comparable characteristics and properties to those at positive polarity, but lower roughness, finer structure and lower coefficient of friction. These coatings can be successfully used to reduce roughness and surface defects and improve the wear resistance of 3D titanium alloys. The pulse energy and polarity of RESР, producing coatings with minimum roughness and maximum wear resistance, have been determined.

The article is focused on the study of the integrity of the material that is used in the automotive industry in process of creating joints by combined technology. The article describes the study of the properties of chemically pretreated surfaces by phosphating technology. When creating new surfaces by phosphating, a new type of phosphate layer was used using modern conductive compounds of polyaniline salts. The pretreated surfaces were investigated in terms of structure, 2D and 3D microgeometry, contact angle in relation to the determination of surface wettability and surface energy. The experiment was realized in order to identify the connections between individual factors of the process and roughness characteristics.

The occurrence of road accidents due to a pavement surface with inadequate roughness is an alarming issue. This problem involves not only the design, construction and maintenance of road pavements, but also the properties of the materials used in the asphalt mixes, traffic volume and vehicle speed, as well as tire characteristics, human factors, environmental conditions and many other contributing elements. As a result, there is a growing awareness of these problems and adequate measures have to be taken by road administrations in order to improve traffic safety. For the design, construction and maintenance of a modern road network, along with strength and sustainability, skid resistance has become an integral part of a safe and efficient road system. With the increase in traffic speed and volume, the road pavements built today must have initial and continuous qualities of high skid resistance. It is a well-known fact that the pavements skid resistance is reduced primarily by mechanical wear and polishing due to traffic action; however, to what extent the friction characteristics are diminished and the other causes and effects of this reduction are problems that road engineers have to face. Although the automotive and tire industries have contributed greatly to the research and development of skid-resistant road pavements, it is quite obvious that most of the improvements will go to pavements. In the following, the paper will focus on establishing the roughness criteria that can be applied from the early stages of the construction of a road infrastructure, by selecting those materials and techniques that lead to a high level of roughness and thus traffic safety. Also, the paper presents the results of recent experimental studies undertaken to determine the road roughness, using the microtexture as well as macrotexture criteria, conducted in Romania on the national roads DN 2 km 212 + 000 and DN 15 km 290 + 870.

Currently, one of the most important and monitored surface properties is the ability to achieve the highest possible level of adhesion after applying a layer of paint or glue. To guarantee this property, it is extremely important to choose the right surface pretreatment. The paper is focused on chemical surface pretreatment and subsequent evaluation of morphological surface changes after application of various selected types of chemical pretreatment based on roughness parameters.

In this work the possibilities of reducing the roughness and defects of surfaces obtained by 3D printing with selective laser melting (SLM), via reactive electrospark surface modification (ESD) with low-melting AlSi alloys has been shown. The influence of the energy parameters of the ESD process on the roughness, microstructure, microhardness and performance characteristics of the coatings has been studied. Surfaces with new phases and ultrafine crystal-amorphous structure with particle sizes from micro to nano level, with new relief, with thickness up to 15 μm and microhardness up to 11 GPa were obtained, as the initial SLM roughness from Ra = 8-11μm is reduced to Ra=3-5 μm. Possibilities for control of the characteristics of the coatings and purposeful synthesis of new phases by changing the parameters of the spark discharge have been established. The parameters of the ESD process, which provide simultaneous reduction of SLM surface roughness, removal and erasure of the defects and targeted reactive synthesis of new phases with high performance properties and wear resistance, are defined and optimized.

Surface quality and its evaluation is currently a very important part of surface preparation for all types of technologies involved in surface formation. Knowledge of the new surface formation mechanism is of great importance from the point of view of production, because it allows to understand the nature and properties of the newly created surface and thus gives the opportunity to both improve the processes used and create a smooth process. surfaces. Therefore, any changes that occur in the surface layer of the component can be considered as changes in the surface quality. The paper deals with the expansion of current knowledge in the evaluation of metal surfaces microgeometry in terms of current trends.