Eastern-European Journal of Enterprise Technologies

Revealing patterns of change in the tribological efficiency of composite materials for machine parts based on phenylone and polyamide reinforced with arimide-t and fullerene

Fri, 28 Jun 2024 00:00:00 +0300

The object of the study is the process of changing tribological efficiency according to tribotechnical characteristics (wear intensity, friction coefficient, temperature in the contact zone) of composites based on phenylone C-1 and polyamide PA-6 with arimide-T filler and fullerene C-60. The study solved the problem of obtaining composites with high wear resistance.

Based on the results of research, it was found that varying the content of arimide-T makes it possible to obtain composites with different patterns of changes in tribotechnical characteristics under conditions of dry friction, lubrication with water and I-50 oil. Composites with the composition: phenylone C-1+15 wt. have the maximum tribological efficiency. % arimide-T+3 wt. % fullerene C-60 and polyamide PA-6+30 wt. % arimide-T+3 wt. % fullerene C-60.

Phenylone C-1 has destructive properties when working in the environment of water and temperature in the friction zone. Its reinforcement with arimide-T and fullerene C60 gave positive results of a complex of tribotechnical characteristics under these conditions. It was found that the wear of composites based on phenylone C-1 in I-50 oil is two orders of magnitude lower than in water. Research of samples from the obtained composites based on phenylone C-1 and polyamide PA-6, reinforced with the optimal content of arimide-T and fullerene C60, showed that their wear resistance when lubricated with oil is 3.5...4.0 times greater than the wear resistance of bronze.

An applied aspect of the reported results is the introduction of manufacturing technologies and restoration of machine parts from the proposed composites. It has been proven that their optimal composition contributes to high tribological efficiency and could provide the required level of wear resistance and reliability of resource-determining nodes, systems, and machine assemblies.

The results could be used by machine-building and repair-technological enterprises

Designing tribotechnical epoxy composite materials reinforced with chopped fibers and modified with silicon organic varnish

Fri, 28 Jun 2024 00:00:00 +0300

The object of research is modified epoxy composite materials containing fibrous fillers treated in physical fields. The technological features of the development of tribotechnical epoxy composites, which must withstand the effects of elevated temperatures, have been considered. In this case, it is necessary to modify the structure of the epoxy polymer matrix, which is achieved as a result of the introduction of heat-resistant organosilicon varnish. Organosilicon varnishes and chopped fibers contain technological additives, which complicates the process of structuring epoxy composites and leads to the appearance of structural defects. Removal of technological additives and cleaning the surface of the aramid and glass fibers from lubricants is possible as a result of processing the components of the composition in physical fields. There is a need to study the influence of physical fields on the structuring processes of the epoxy system and the formation of the structure of epoxy composites with specified properties. Modified epoxy composites contain chopped aramid and glass fibers treated with ultrasound. The tribotechnical characteristics of epoxy composites were studied at a sliding speed of V=1.0 m/s with a change in specific load from 0.5 MPa to 1.5 MPa. The temperature in the tribocontact zone during frictional interaction rises to 100 °C with an increase in the specific load. An increase in the density of the surface layer of tribocontact of epoxy composites with fillers treated in physical fields was revealed. The practical recommendations have been compiled for the implementation of the treatment technology of components in physical fields, which ensures structuring of epoxy composites with high tribotechnical characteristics

Determining patterns of leaching titanium(IV) from the Irshansky deposit ilmenite

Fri, 28 Jun 2024 00:00:00 +0300

The research object is the ilmenite concentrate from the Irshansky deposit. This study describes an elemental composition of the mineral raw material and confirms its structure using the X-ray diffraction and scanning electron microscopy. Experimental studies have shown that the ilmenite concentrate from the Irshansky deposit has a significant titanium content in terms of titanium dioxide (79 %). Mineral raw materials with such a chemical composition are unique, so there is a need to find alternative methods for its processing. The research demonstrates that the maximum degree of extraction in the process of alkaline leaching of the ilmenite concentrate is achieved under the condition that the average diameter of particles of the mineral raw material should be ≤71 μm. As a result of temperature studies, it has been found that a temperature of 453 K would suffice to obtain potassium titanate at atmospheric pressure. Further temperature increase does not provide for a significant increase in the degree of titanium extraction, and also contributes to the formation of polytitanates of various compositions. The study of the influence of the molar ratio of the starting reagents on the degree of extraction of titanium(IV) from the ilmenite concentrate has showed that the optimal molar ratio between the components corresponds to the stoichiometric one and is 1:2. Increasing the amount of potassium hydroxide in the reaction mixture is impractical as it reduces the yield of potassium titanate, and the final product will have high alkalinity due to excess alkali. The optimal time for alkaline leaching is three hours of continuous heating in a glycerin bath. A further increase in the duration of heating does not lead to an increase in the degree of extraction, which is associated with the diffusion of alkali from the surface of the nucleus into the volume of ilmenite particles due to the formed products of interaction and annihilation of the initial nuclei

Determining technological parameters for obtaining ta15 titanium alloy blanks with improved mechanical characteristics using the electron-beam 3D printing method

Fri, 28 Jun 2024 00:00:00 +0300

The object of this study is the process of electron beam 3D printing of articles made of TA15 titanium alloy powder. Peculiarities of the structure and properties formation of alloy blanks, obtained by this method have been described. Influence of process parameters (electron beam power and geometric scanning parameters) on the characteristics of the material were considered.

Step of displacement of the beam trajectory changed from 0.1 to 0.25 mm with an interval of 0.05 mm. Specific energy of the electron beam varied from 20 to 70 J/mm³ for every trajectory displacement step.

The macrostructure was examined visually while the microstructure was studied by optical microscopy. Mechanical properties were determined by uniaxial tension and impact bending tests. It was established that depending on the 3D printing parameters the macrostructure of most samples is dense but with unfavorable parameters non-fusions or shrinkage porosity defects may form. The microstructure of the dendritic type has an α´+β lamellar-acicular morphology, its dispersity and shape of α´–phase areas vary depending on the process parameters.

A scanning step of 0.2 mm and a beam energy of 40 J/mm³ allows obtaining a dispersed microstructure in which there are no non-fusions and shrinkage micropores. The value of the R_m is 27 %, and the R_0.2 is 24 % higher than that of the alloy obtained by the conventional technology of electron beam melting. The A₅ is 3.2 times higher. However, impact toughness of the sample with dendrite unfavorable orientation to the direction of load applying may be lower compared to conventional technology. The results could be used for devising commercial technology of high strength titanium alloys parts produced by 3D printing

Enhancing side die resistance to thermal shock in automotive casting: a comparative study of FCD550 and SKD6 materials

Herry Patria, Iwan Susanto, Belyamin Belyamin, Dianta Mustofa Kamal — Fri, 28 Jun 2024 00:00:00 +0300

Enhancement of side die resistance to thermal shock in mold disc car applications was achieved by substituting FCD550 material with SKD6 material. The primary issue addressed is the cracking of side dies due to thermal shock induced by an accelerated production process, leading to production halts and failure to meet large customer orders. The study aims to identify a material that can better withstand thermal shock than FCD550, thereby improving the durability of side dies and the overall productivity of the manufacturing process. The research involved direct production experiments, analyzing the materials FCD550 and SKD6, evaluating die characteristics, and assessing finished product attributes before and after material changes. Laboratory tests and machine-setting trials were conducted, varying production processes and assessing the results. The findings indicate that SKD6 is significantly more resistant to thermal shock than FCD550 in mold disc car applications. The study compared the strength of side die materials using data sheets and adjusted setting parameters under existing cooling conditions. Experimentation involved altering the standard temperature from 520 °C–545 °C to 532 °C–538 °C and reducing the soaking time from a minimum of 270–540 seconds to 332 seconds. This reduced soaking time from 69 seconds to 46 seconds and aging time from 190 seconds to 180 seconds, increasing casting productivity from 194,870 pieces/28 days to 213,311 pieces/28 days across seven machines, thereby fulfilling the customer’s requirement of 200,000 pieces/28 days without side die cracks. Durability testing on five product samples according to TSD5605G standards confirmed the quality as meeting customer specifications

Synthesis of NiCrAlY nano-scale powder by high-energy ball milling process for thermal spray coating application

Irma Pratiwi, Husaini Ardy, Budi Prawara, Raden Dadan Ramdan, Fahdzi Muttaqien — Fri, 28 Jun 2024 00:00:00 +0300

These days, during the issues of climate change, there has been a shift in the energy industry from using fossil fuels to more environmentally friendly fuels such as biomass fuels. Biomass fuel is considered CO₂ neutral because the carbon produced during combustion in the form of CO₂ emissions can be used for new plant growth. However, besides the advantages of using biomass fuel, a problem arises when biomass fuel contains a high concentration of corrosive agents, which can be released along with hot fuel gas. These corrosive agents can damage the boiler components. Coating technology is one of the solutions to protect components that work at high temperatures against the corrosion threat. One type of coating that can be used in high-temperature applications is NiCrAlY coating by the high-velocity oxide (HVOF) process. One interesting topic that people are developing is using nano-scale coating to increase the coating’s resistance against hot corrosion and cracking. Nano-scale powder feedstock is needed to produce nano-scale coating material. In this research, top-down method is used to synthesis nano-scale powder. One of top down method, the high-energy ball milling processs, is a promising method to synthesize nano-scale powder material. Therefore, in this research, the ball milling process is used to prepare nano-scale product. The results showed that this method was successful to make the nano-scale powder. The nano-scale powder was characterized by several methods to investigate the morphology and properties of the powders. However, there are still many challenges in producing nano-scale powder that meets HVOF feedstock powder requirements. In the long run, it is expected that this research can answer those challenges so that at the end, the good quality of nano-scale powder can be achieved

Establishing patterns in the structure formation of polymer nanocomposites based on polyamide 6 during their crystallization processes

Fri, 28 Jun 2024 00:00:00 +0300

This paper reports experimental and computational studies on patterns in the structure formation of polymer nanocomposites when different types of fillers are used. The study was conducted for nanocomposites based on polyamide 6 filled with carbon nanotubes or silicon dioxide nanoparticles. In the course of research, the mass fraction of the filler varied from 0.2 % to 4.0 %, and the cooling rate of the melt composite varied from 0.5 K/min up to 20 K/min.

Data on experimental and theoretical studies into the mechanisms of structure formation of composites according to the method, which includes two stages, are given. According to the first stage, crystallization exotherms of nanocomposites were experimentally obtained when they are cooled from the melt at a given constant rate. The dependence of various characteristics of the crystallization process on the mass fraction of the filler and the cooling rate of the composite was established.

At the second stage, based on the analysis of the obtained crystallization exotherms, theoretical studies were performed to determine the mechanisms of structure formation of nanocomposites at different stages of crystallization. For the initial stage, according to the nucleation equation, the presence of two mechanisms of structure formation – planar and volumetric – has been shown.

Within the framework of the Kolmogorov-Avrami equation, the mechanisms of structure formation at the next stage of crystallization were established, which corresponds to the formation of ordered structures in the material within the volume of the polymer composite as a whole. The research was carried out assuming the existence of a mechanism of crystallization of the polymer matrix itself, which is realized on fluctuations in the density of the polymer, and a mechanism of crystallization, the centers of which are filler particles.

The use of the proposed nanocomposites is promising for the manufacture of parts of energy equipment, electronic equipment, elements of chemical, processing, defense industry installations, etc.