Papers by Keyword: Powder

Abstract: One of the most important issues in the procurement of parts and products by the process of metallurgy is the design of the details of the press-mold. The design should be carried out in such a way that the additional mechanical processing of the purchased parts and products is minimal. The tooling and technological scheme of the press-mold should be selected as might it be economically viable and the mechanical processing stakes are small. For these purposes, in this present study, the valve part of the high-pressure drilling pump НП-720х105, which is widely used in the oil and gas complex, was selected for theoretical and experimental investigations. With the help of the software, in order to ensure equal distribution of residual porosity in the samples, the optimal size and configuration of the samples were determined, and the inner and outer conical walls of the asymmetric samples were subjected to dynamic hot pressing. "Valve seat" and "valve tray" of the НП-720х105 high-pressure three-plunger pump were used for the experimental studies. From the conducted tests, it became clear that during the preparation of abrasive steels with high impact-abrasive corrosion resistance, it is necessary to thoroughly study the chemical and granulometric composition, structure, and strengthening process. Theoretical and experimental results show that the technology of manufacturing parts resistant to impact-abrasive corrosion allows the obtained parts to work in conditions of high impact-hydroabrasive corrosion.

Abstract: In this study eggshells and low density polyethylene plastic (LDPE) wastes were reused to produce tiles. The eggshells were ground in a laboratory scale jar mill into the particle size of fine sand. The optimum grinding parameters were determined to be the setting that produced the highest mass of eggshell powder that was within the desired particle diameter size range of 0.425 mm (No. 40) and 0.075 mm (No. 200). A two to the three factorial design of experiment was used with variables of Time, Speed, and Ball Filling Ratio. The high and low values used in this study were 20 minutes and 10 minutes for the time, 250 rpm and 100 rpm for the speed, and 35% and 20% for the ball filling ratio. There were eight settings made with 3 trials per setting and one validation for the optimal setting produced. The eggshell powder produced by the optimal setting of the jar mill was used to create the LDPE-eggshell tiles. Four tiles were made for the three trials and for the validation part. The tiles were tested for its relative strength using the Compression Testing Machine. The researchers determined that eggshells and LDPE plastics may be formed into tiles and that the strength of the tiles that were produced by these materials exceeded the standard value set for this type of product.

Abstract: The recovery of a fractured femur using the plate and screw internal fixation. The plate internal fixation is made of metal has good mechanical strength, but causes allergic reactions, secondary surgery, stress shielding and high costs. Evaluation of the lack of metal, now developed biodegradable polymers use Polylactide (PLA) and Poly ɛ-caprolactone (PCL). The advantages of PLA and PCL materi-als can control the rate of degradation and increase mechanical strength. Manufac-turing processes of the plate fixation internal using cold isotactic pressing. Inde-pendent variable on the PLA/PCL blends from 90/10, 80/20, 70/30, and 60/40 wt% and tested for FTIR, XRD, SEM, density and porosity. Result from adding PCL make the degree of crystallinity is decreased significantly. The formation of semi-crystalline the with peak width smaller and the crystal size bigger in the 60PLA sample. PLA/PCL blends largely formed bonding and some immiscibility in the form of small flakes and cavities after the addition of PCL content. Large cavities reduce density and increase porosity which can affect mechanical proper-ties. 90PLA sample has high density and low porosity of 1,186 g/cm3 and 4% porosity, respectively.

Abstract: The aluminum 4.5 wt. % copper alloy was melted in an electrical resistance furnace and atomized to produce the powder of 350 µm to 500 µm size of different shapes and sizes. The atomized powder was graded using standard set of sieves. The powder is compacted with the help of spark plasma sintering by applying the required pressure and temperature simultaneously. The sintering pressure of 25 MPa and temperatures of 480 °C and 540 °C was employed to produce sintered compacts at two different temperatures. The density of the sintered compact was measured using Archimedes principle. The surface topography of both the compacts revealed the cellular, elongated grains and dendritic microstructure. The average micro Vickers hardness of compact sintered at 480 °C and 540 °C were found to be 55.9 HV1 and 65.4 HV1 respectively. The compression strength of compact sintered at 480 °C is 185 MPa and the compact sintered at 540 °C is reported as compacts was reported as 250 MPa.

Abstract: In order to predict the effect of the Marangoni convection and the morphology of melted stainless steel powder, during the selective laser melting (SLM) process, a transient three-dimensional numerical model is developed at the mesoscale. The evolution of the temperature and velocity fields’ is then studied. The initial powder bed distribution is obtained by the discrete element method (DEM) calculation, and the temperature distribution and the molten pool shape deformation are calculated and analyzed by the Ansys-Fluent commercial code. The molten pool shape is obtained by considering the influence of Marangoni convection on the internal flow behavior. The recoil force was not considered in our calculation. As main results, a slight deviation between the position of the maximum temperature of the molten pool and the center of the laser spot is observed. The direction of the heat diffusion is more likely to be horizontal and the flow centrifugal, which causes the melt track to be wide. Finally, the Marangoni convection is the main driver of the flow.

Abstract: It is determined that the active components of modern concrete are active mineral fillers, such as microsilica, meta-kaolin, ash-bearing or compositions from them, as well as superplasticizers. The optimal combination of these additive modifiers allows you to control the rheological properties of concrete mixtures and to modify the structure of the cement stone in such a way as to provide concrete properties that provide high operational reliability of structures. However, they have certain disadvantages that hamper their widespread use. The purpose of the research is to determine the effect of reaction powders applied simultaneously with colloidal surfactant, on the strength of powdered concrete and the rate of its formation.

Abstract: The powders of the BiInSn alloy were produced by the ultrasonic atomization and the ultrasonic mixed crushing using the different dispersants. In this study, the composition, microstructure, melting point, and size of these powders were observed. The viscosity of different solutions of the dispersants and the mechanical properties of the sintered bulk materials were also tested. From the data analysis and results, we found that the composition of the powders using the different methods was consistent with the as-cast state. In addition, the size of powder produced by ultrasonic mixed crushing was significantly smaller than that ultrasonic atomization. And during the ultrasonic crushing process, with the increase of the viscosity of the dispersant, the size of the final powder also decreased, and even submicron powder were produced. The product of submicron powder could effectively improve the density and mechanical properties of sintered materials. And the principles of ultrasonic atomization and ultrasonic mixed crushing were discussed. We found that the mechanism of ultrasonic mixed crushing to produce powder was the micro-shock-wave theory of ultrasonic cavitation. At the same time, these dispersants were effective in keeping the droplets separate from each other and preventing them from merging back into the larger droplets. The droplet was solidified into a powder by rapid cooling in the end.

Abstract: Research and development related to the processing of recycled materials has grown progressively in recent times, as scientists endeavour to integrate sustainability criteria, depletion of natural resources, reducing the energy of technological processes involving extraction and processing of raw materials, etc. When it comes to processing slate, industries have to pass over several steps ranging from the extraction of rock blocks until the final products consisting of plates, leaving behind a considerable amount of waste in the form of a mud composed mainly of water, lubricants and crushed rock. This waste with no defined destination accumulates in yards, reservoirs and streams, affecting the environment. Slate powder has great prospects for recovery, recycling and further applications once it has chemical composition and components similar to raw materials used in ceramic and building construction industries. Therefore, a complete characterization of this powder is important and here we present some results of XRD, SEM, EDS, G3 morphology and thermal analysis of slate powder samples from the southeastern state of Minas Gerais in Brazil.

Abstract: The effect of beryllium hardening has been studied. Beryllium is sintered by method of hot isostatic pressing (HIP), depending on the temperature of powders pressing. The research results of electron microscopic studies were the base for demonstrating formation of the hydraulic phase at the grain boundary of sintered beryllium and influence of the reinforcing phase on the mechanical properties of the HIP blank. The dependence of beryllium precision elastic limit and conventional yield strength from the size of the reinforcing particles of beryllium oxide has been found. The obtained equation provides a description of the “dispersion-grain-boundary" mechanism of isostatic pressed Beryllium hardening.

Abstract: The main requirement for powders for additive machines is the spherical shape of the particles. Such particles most compactly fit into a certain volume and provide the “fluidity” of the powder composition in the material supply systems with minimal resistance. Based on the peculiarities of the methods of obtaining spherical powders in order to obtain spherical granules of a regulated grain size, the technology of electroerosive dispersion, which is distinguished by relatively low energy costs and ecological cleanliness of the process, is proposed. The main advantage of the proposed technology is the use of waste as raw materials, which is much cheaper than the pure components used in traditional technologies. In addition, this technology is powder, which allows to obtain powder-alloys. The widespread use of the method of EED for the processing of metal waste into powders for the purpose of their reuse and application in additive technologies is hampered by the lack of complete information in the scientific and technical literature on the influence of the original composition, modes and media on the properties of powders and technologies of practical application. Therefore, the development of technologies for the reuse of EED powders and the evaluation of the effectiveness of their use requires the conduct of comprehensive theoretical and experimental studies. The purpose of this work was to obtain and study additive products from electroerosive cobalt-chromium powders of a specific particle size distribution and to study their microstructure. The granulometry of the obtained powders was determined on a laser analyzer of particle sizes “Analysette 22 NanoTec”. The microstructure of additive samples from cobalt-chromium powders (by transverse polishing) was investigated by optical microscopy on an inverted optical microscope OLYMPUS GX51. On the basis of completed studies, aimed at obtaining and studying additive products from electroerosive cobalt-chrome powders of a specific particle size distribution, and studying their microstructure, it was found that additive samples, obtained from a cobalt-chrome powder with an average particle size of 35,68 microns, have practically no pores.