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

There has been growing interest in the use of the sol-gel approach to form high-quality dielectric materials. Their tailored properties allow for developing functional electronic devices in a scalable and rapid manner. According to physicochemical principles, the displacement and response behavior of charges under an applied external field can manifest in unique dielectric properties, providing useful information to improve the process, design, and quality of electronic devices. Therefore, a systematic and in-depth investigation of the fundamentals of sol-gel dielectrics is necessary. In this Research Update, we present recent advances in various sol-gel-processed dielectric materials and their applications to functional electronic devices. A brief introduction to sol-gel chemistry to form oxide dielectric films and the basis of physical mechanisms under electrical fields are discussed. Along with the dielectric properties, recent achievements of proofof-concept experiments and their various applications to functional electronic devices are introduced. It is expected that further innovations in solution-processed metal oxide dielectrics will achieve cost-effective high-performance functional electronics in the near future.

Recent most important improvements in metal cutting industry are utilization of cutting tool and tool condition monitoring systems. These systems help to prevent damage to both machine tools and workpieces. New technologies in optical measurements allow construction of tool condition monitoring systems which does not affect manufacturing processes and are relatively cheap to build because of low prices of optical sensors compared to standard sensors and measurement techniques, built on cutting machines. Our paper summaries various monitoring methods for tool condition monitoring in the milling processes that use optical sensors and optical methods combined with machine vision and image processing, that have been practiced and described in literature.

In the industry, the concept of “production quality” means a very important and inseparable role, which has a large share in the final quality of the product. Various factors affect product quality. Above all, state-of-the-art technologies are used in every industry, which helps to adapt quickly and efficiently to changes in market conditions, which has a significant impact on the competitiveness of manufacturers to become market leaders. The manufacturers ‘efforts are made to produce a flawless product that will excessively meet customers’ requirements for the perfect product. An integral part of the production process is the quality control of products at certain stages of production. Measurement requirements are defined by satisfactory accuracy, variability, total cost and speed. An important factor in product inspection is currently the creation of a three-dimensional virtual model of a real product, where you can easily compare the created 3D model with the original CAD model and display dimensional deviations.

In this study, the effect of overlay paper properties on the surface quality of laminate flooring was investigated. For this aim, only the upper surface of 22 gr/m² raw overlay papers impregnated with 53% melamine formaldehyde resin in the glue pool was sprinkled by corundum (Al2O3) in two different ratios (23 and 28 gr/m²) from different companies at 140-160 ºC. In the drying ovens, the impregnated overlay papers with a final weight of 135 and 140 gr/m² and a humidity of 7.5% were produced. The panels obtained at the end of these processes were tested according to TS-EN 14323 and related standards, which are surface quality features such as surface abrasion, surface scratch and ash test. According to the test results, it has been observed that under the same pressing conditions, different corundum type and amount as well as laminate floorings covered with overlay papers with different final weights have an effect on the surface quali ty properties. It was observed that although the increase in the amount of corundum did not have a significant effect on surface scratching, it had a significant effect on surface wear values. According to the results of the ash test, it was observed that the amount of corundum increased and its distribution on the overlay paper surface was homogeneous.

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.

This paper deals with the investigation of the effect of speed on the form fit joint of dissimilar materials. Thin -walled materials based on steel and aluminium alloy were joined by thermal drilling. The shape and size of the resulting bushing were evaluated. It turned out that the best material combination for joining by flowdrill technology are joints made of steel and aluminum alloy. Aluminum alloy must always be placed in the bottom position. The best parameters of the formed bushing were achieved with the combination of DC-Al or TL-Al materials, at tool speeds of at least 2400 rpm.

The article presents the results of increasing the accuracy of the operating parameters of the electron flow (power density, speed of electron-beam processing) in obtaining optical plates of small thickness as components of optical instrumentation devices. It is shown that flexible control of such parameters of tape electron flow allows to significantly (1.5-2 times) increase the accuracy and quality of surface processing of small thickness (up to millimeters) optical silicate plates (glass K8) by low-energy electron flow. The implementation of such management was carried out using an information-measuring system, the general principles and functional scheme of which are given in this article. The proposed system allows with high accuracy (relative error does not exceed 4.5%) and efficiency (the time between the moment of
determining the parameters of the electron flow to the moment of its formation with the adjusted values of these parameters does not exceed 12-17 μs).

The main goal of this contribution is study the microgeometry of blasted surfaces. The aim is to design suitable microgeometric characteristics for the description of pretreated surfaces, experimentally verify the influence of blasting agents of various shapes and sizes on the microgeometry of metal surfaces. The following types of evaluation are used to meet this goal: 2D roughness determinat ion and profilograms, 3D surface visualization and surface volume determination. The results of the experimental part will contribute to the optimization of technological parameters of the tearing process.

The article describes the concept of a new forging method of circular cross-section blanks in a forging tool, the design of which makes it possible to develop significant alternating deformations in the deformable metal. The results of comparative studies of the microstructure and mechanical properties of AISI-5140H low-alloy structural steel, formed in a new forging tool that implements alternating deformation and in flat strikers are presented.

At present, various types of steel grades are used in the production of welded structures and assemblies, resp. combinations of ferrous and non-ferrous metals. In these mutual combinations, it is necessary to know the specifics of weldability of both materials, to choose a suitable welding technology and a suitable filler material. In the experimental part, the quality of heterogeneous welded joints was verified by the GMAW method. A protective gas atmosphere of 82% Ar + 18% CO2 was used for welding (M21 – ISO 14175: 2008). The possibilities of welding and mutual combinations of austenitic stainless steel with structural non-alloy steel, structural alloyed high-strength steel with structural non-alloy steel were assessed. The quality of welds was evaluated using non-destructive and destructive tests in terms of standards: visual test STN EN ISO 17637, capillary penetration test STN EN ISO 22476-12, internal errors were evaluated using radiation tests STN EN ISO 17636-1. The destructive tests used the tensile test STN EN ISO 6892-1, the weld fracture test STN EN ISO 5173 and the Vickers hardness test STN EN ISO 6507-1, the bending impact test STN EN ISO 9016 and the metallographic analysis according to STN EN ISO 17639.

A thin nitinol wire with a diameter of 0.05 mm was used as a surface sensor indicating deformation changes of the polypropylene tube during bending. Two types of nitinol wire windings were compared: parallel placement with the longitudinal axis of the tube and transverse windings around this axis. Changes in the electrical resistance of the wire were measured during the bending deformation. The sensitivity of the nitinol sensor, its comparison with conventional wire metal resistance strain gauge made of constantan alloy, its application possibilities, as well as the advantages resulting from the different winding geometry were discussed.

The bearing monolithic reinforced construction of “Open Fuel Storage” of SOLVAY SODY AD, Devnya, has been operated for more than 40 years in conditions of extreme stress and external aggressive factors. All this has logically led to the presence of serious corrosion damages. The basic requirements for developing a technical solution for repair and restoration of defect structures retaining walls (assembly type), supporting beams and columns, is the bringing of the technical characteristics of the reinforced concrete structure in its initial (design) or better condition. The report discusses the features of the proposals as the most effective technological method for repair, based on the possibilities for the formless construction of a new special thin repair concrete layer restoring the original cross-section, applied with the methods of “wet” shotcreting. A composition of high -tech concrete with the participation of an internal crystallization chemical admixture and a shrinkage-compensating one suitable for shotcrete is proposed. Specific details have been developed for the renovation of the individual structural elements, as well as optimal technological regulations for the implementat ion of the repair.