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

The article presents the results of research aimed at applying selected optimal topography modification procedures to critical areas of shaped parts of molds in order to increase their service life. Molds for high-pressure casting of aluminum alloys were evaluated. The microgeometry of the sample surface was modified by low-energy laser radiation microtexturing. Lattice and stochastic textures were created by laser radiation. The integrity of the sample surfaces after the formation of ablation craters was checked by scanning electron microscopy. The dimensions of the random texture craters on which duplex PVD coating nACRo4. The tribological properties of surfaces with different microtextures were evaluated using the pin-on-ball method.

This study presents a comparative analysis of three types of coatings taken from the active area of the coted harrow disks using atmospheric plasma spray deposition method (APS). The resulting coatings increase the durability of the harrow discs and the inclusion in the componence of coatings of carbides and powdered ceramic compounds will enhance the mechanical characteristics. This study focused on scanning electron microscopy of the coated samples from the harrow discs and their tribological properties. SEM imaging and EDS analysis have been carried out to clarify the morphological characteristics and study of disc cross-section. Tribological tests were carried out to determine the following main parameters: adhesion to the substrate, coefficient of friction (COF), modulus of elasticity and hardness of the material.
The development and implementation of modern technologies for improving the mechanical and chemical properties of materials for
coated harrow discs will increase resistance to abrasive wear in modern agricultural conditions.

High-entropy alloys were first extensively described in 2004 [1]. Despite the increasing scientific interest in these materials, there is still much to discover. The AlCoCrFeNi alloy is one of the most popular HEAs. Scientists often study the mechanical properties of this alloy and the effect of varying the different component contents on its properties [2,3]. There are also studies on the effects of alloying additives on structure and properties [4,5]. In this study, high-entropy alloys were obtained by induction melting. The influence of aluminium content and titanium addition on tribological properties of AlxCoCrFeNi alloy was tested. Furthermore, the alloys were characterised by X-ray diffraction (XRD), hardness, and microstructure examination. The occurring wear mechanisms and tribological properties of the tested high-entropy alloys were analysed and compared with the results obtained for C45 steel. The received results confirm the influence of Al content in AlxCoCrFeNi alloy and Ti addition on tribological properties

In this paper, we present the results of the tribological studies of commercially pure copper (99.9% Cu) and a low-alloyed chromium bronze (Cu-0.5%Cr), contacting a graphite-containing material. The samples under study were produced with two types of microstructures: a coarse-grained (CG) one, having an average grain size of 100-130 μm after annealing, and a submicrocrystalline (SMC) one, having an average grain size of 0.30-0.50 μm after multi-cycle severe plastic deformation (SPD) processing via equal-channel anglar pressing (ECAP) combined with Conform. It is shown that for the samples produced by ECAP-Conform, having an SMC structure, the friction coefficients are 12 – 20% lower than for the as-annealed samples, having a CG structure.

The effect of metal phase composition in the Fe-based + (2 % glass) powdered composites on the basic mechanical and tribological properties of the composites, made by means of sintering and hot forging, have been investigated. As a basis for the metallic phase of the composite the mixtures of iron powders with additives of graphite, B₄C, BN and Cu at different ratio were used. It was shown that at sintering of metal-glass material the reaction of glass phase with oxides on the surface of iron powder particles takes place, resulting in a change of glass phase chemical composition. The results of materials mechanical properties investigations had shown that the highest strength properties and hardness have the composites with the content of the initial powder mixture of 5% Cu and 2% B₄C, while the best tribological properties have the composites with 2% B₄C, 5% Cu and 1% BN.

This work presented the results of tribological studies of commercially pure copper (Cu 99.9%) and low-alloyed chrome bronze Cu-1%Cr in contact with a graphitiferous plate EK-40. Samples from copper and copper alloy were prepared to obtain two kinds of grain size of microstructure. Two schemes were used for tribological studies. The first scheme was used during reciprocal movement to evaluate the friction coefficient. The second scheme was employed to evaluate the shear strength of adhesive bonds and the adhesive component of the friction coefficient.Besides, the fulfilled studies determined that the tribological properties of materials depended on the grain size of microstructure. It is shown that an ECAP–Conformed specimen with UFG exhibits 20-30% lower friction coefficients than that of annealed specimen with CG structure. The tribological test results showed that the coefficient of friction decreased, with the decreasing grain size. Therefore, were conclude the coefficient of friction of proposed materials is microstructure-sensitive.