Search Results (8)

This paper presents the results of research work on the revised design of a deep hole boring tool. The study was divided into three stages: theoretical, experimental and operational. In the theoretical part, a 3D model of the actual boring bar was created, which was subjected to strength tests using the Finite Element Method (FEM), and then prototypes of new deep hole boring tools were made with structural modifications to the shank part of the tool. For the polymer concrete core of a shank, there was a 14.59% lower displacement, and for the rubber-doped polymer concrete (SBR—styrene butadiene rubber) core of a shank there was a 4.84% lower displacement in comparison to the original boring bar. In the experimental part of the study, the original boring bar and the prototypes were subjected to experimental modal analysis and static analysis tests to compare dynamic and static properties. In the operational part of the study, boring tests were carried out for various workpiece materials, during which the basic parameters of the surface geometric structure (SGS), such as roughness Ra and Rz, were studied. Despite the promising preliminary results of the theoretical and experimental studies, using the described modifications to the boring bar is not recommended. Full article

A series of new types of composites (biopolymer–silica materials) are proposed as selective and effective adsorbents. A new procedure for the synthesis of chitosan–nanosilica composites (ChNS) and chitosan–silica gel composites (ChSG) using geometrical modification of silica and mechanosorption of chitosan is applied. The highest adsorption efficiency was achieved at pH = 2, hence the desirability of modifications aimed at stabilizing chitosan in such conditions. The amount of chitosan in the synthesis grew to 1.8 times the adsorption capacity for the nanosilica-supported materials and 1.6 times for the silica gel-based composites. The adsorption kinetics of anionic dyes (acid red AR88) was faster for ChNS than for ChSG, which results from a silica-type effect. The various structural, textural, and physicochemical aspects of the chitosan–silica adsorbents were analyzed via small-angle X-ray scattering, scanning electron microscopy, low-temperature gas (nitrogen) adsorption, and potentiometric titration, as well as their adsorption effectiveness towards selected dyes. This indicates the synergistic effect of the presence of dye-binding groups of the chitosan component, and the developed interfacial surface of the silica component in composites. Full article

The paper extends the concept of cut edge quality and examines the fibre laser cutting process. A Prima Power Platino Fiber Evo device with a reference speed (RS) of 3500 mm/min was used for laser cutting. In order to analyse the influence of the laser cutting speed on the cut edge quality of X5CrNi18-10 stainless steel sheets, macroscopic studies were conducted on a stereoscopic microscope and surface stereometry on a confocal microscope. The obtained results were analysed to evaluate 2D and 3D parameters. These parameters make it possible to determine the cut edge quality and the susceptibility to the application of protective coatings. It was observed that the value of the Sa parameter is the highest for a cutting speed equal to 130% of RS. The Sz parameter is similar, while the Sk, Spk and Svk parameters rise as the speed increases, which is a negative phenomenon. Comparative tests were also conducted for four specimens made at cutting speeds of 70%, 85%, 100% and 115% of RS, respectively. It was found that the laser cutting speed has a significant impact on the cut edge quality and that stainless steel can be cut while maintaining the technological regime at 115% of RS. Full article

A characteristic feature of sintered stainless steel (SSS) is its porosity. Porosity results in a lower density of steel, making attractive components for producing lightweight structures and materials used in industry (e.g., the automotive industry or aerospace). Scientists also observe that porosity adversely affects steel’s properties, especially its strength properties. One of the proposals for improving the discussed properties is the use of surface treatment of sintered stainless steels, e.g., with the use of concentrated energy sources such as plasma beams or laser beams. However, this proposal is an incidental subject of research, which is not justified from the point of view of the obtained research results presented by a few research groups. In this study, the surface modification (surface treatment) of sintered stainless steel was presented. The authors proposed the use of two surface treatments in order to compare them and obtain the best results. The first treatment was the deposit of Cr₃C₂–NiCr coatings on SSS surfaces using the atmospheric plasma spraying (APS) method. The second treatment was to create surface layers on SSSs by laser alloying the surface with a CO₂ laser. Due to high precision and ease of automation, the most common methods in surface alloying treatment are laser technologies. This research’s main aim was to analyze the microstructure and strength properties of the SSS surface layer. The research confirms that applying the Cr₃C₂–NiCr coating and modifying the surface layer through the laser alloying method improves the mechanical properties of SSSs. Full article

The article presents the effect of the anodizing parameters, as well as the thermo-chemical treatment, of Al₂O₃ layers produced on an aluminum alloy on the characterization of structure, geometrical structure of the surface (SGS), the thickness of the oxide layers, the phase composition, and their microhardness. The oxide layers were produced by the method of direct current anodizing in a three-component electrolyte. Then, thermo-chemical treatment was carried out in distilled water and aqueous solutions of sodium dichromate and sodium sulphate. The anodizing parameters and compounds for the thermo-chemical treatment were selected on the basis of Hartley’s plans. The research showed the effect of anodizing parameters on the thickness of the Al₂O₃ layers and the increase in the thickness of the layers as a result of the thermo-chemical treatment. The research showed a significant increase in the microhardness of the layers as a result of thermo-chemical treatment and its influence on the phase composition of Al₂O₃ layers. A significant influence of the thermo-chemical treatment on the geometrical structure of the surface was also found. Full article

The main objective of the present work is to determine the effects of laser processing on properties of WC-Co electro-spark deposited (ESD) coatings on steel substrates. Tungsten carbide coatings have been applied to steel substrates using a manual electrode feeder, model EIL-8A. The laser beam processing (LBP) of electro-spark coatings was performed using an Nd:YAG fiber laser. The microstructure and properties of laser treated/melted coatings were evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), surface geometric structure (SGS) and roughness measurements and adhesion, microhardness, residual stresses, corrosion resistance and application tests. The obtained experimental data were subjected to statistical analysis and multidimensional numerical and visual exploratory techniques. It has been shown conclusively that the laser-treated ESD WC-Co coatings are characterized by lower microhardness, higher resistance to corrosion, increased roughness and better adhesion to the substrate. LBP homogenizes the chemical composition, refines the microstructure and heals microcracks and pores of ESD coatings. The laser treated ESD WC-Co coatings can be used in frictional sliding nodes (e.g., on the front seal rings used in pumps) and as protective layers. Full article

The production of modern machines requires parts with much greater geometric accuracy and surface geometry (SG) precision than several years ago. These requirements are met by so-called hybrid technologies that must simultaneously be inexpensive to implement. The integration of treatment procedures (usually in one operation) is geared towards achieving a synergistic effect. Combining different treatments from various technologies produces synergy, i.e., benefits greater than the optimization of each individual process done separately. This paper presents experimental results and numerical experiment data on surface plastic deformation. The hybrid technology used in the study was a combination of milling and finishing with plastic burnishing using a ceramic ball. These processes were integrated on a multi-axis CNC machining center. The plastic deformations of real surfaces were determined in simulations. The paper also discusses the structure of the model and how to use it to conduct a finite element method (FEM) computer simulation. The aim of the study was to determine how to use the potential developed model of hybrid treatment to predict the surface performance expressed by the amplitude, volume, and functional parameters of the surface geometry, with the EN-ISO 25178-2 profile. Full article

Nanotechnology is currently a very promising field of materials science. One of the most recent directions of research in this field is the nanotechnology of the upper layers for applications in engineering kinematic systems. The paper presents the influence of the production parameters of Al₂O₃ oxide layers on an EN AW-5251 aluminum alloy substrate on the nanostructure, nanomorphology of these layers, and their energy condition. The energy level was determined on the basis of Surface-Free Energy (SFE), determined from wettability (contact) angle measurements using the Owens-Wendt method. Using systematic scanning, the geometric structure of the surface (SGS) was determined for the produced layers. By means of a scanning electron microscope (SEM), the surface morphology and structure, and the chemical composition of the layers (EDS) were analyzed. Computer analysis of the surface nanoporosity was performed by means of the ImageJ 1.50i program. It was noted in the investigations that the oxide layer production parameters induce changes in the surface free energy of the layers. Changes in the nanomorphology of the upper layers were also observed, depending on the anodizing parameters. Full article