Papers by Keyword: Pressing

Abstract: The pressing and sintering processes of copper powders produced by different methods are studied in the paper. The main research is based on PMS-1 powders, obtained by electrolysis. To find the easiest and the most reasonable sintering mode, the process is carried out in the open air and dissociated ammonia atmosphere. The samples parameters after each processing procedure were calculated, compression tests were carried out. Basing on preliminary experiments the masses and sintering modes of rectangular shape forms used for equal channel angular pressing were figured out. The possibility in principle to carry out the process of equal channel angular pressing of porous sintered samples without metal damage was shown.

Abstract: Various types of deformed semi-finished products are prepared from aluminum alloys, such as plates, sheets, tapes, foil, panels, profiles, pipes, rods, forged pieces, wires. These semi-finished products are obtained by processing ingots of continuous casting by pressure - rolling, rolling-off, pressing, forging, stamping or drawing. Pressed semi-finished products are made of aluminum alloys in the majority of cases. The work examines the study of the evolution of the half-finished products microstructure at different stages of their manufacturing in several passes and shows the possibility of obtaining strips of fine-grained structure using pressing in a special device. Also, the research established that, in the material of half-finished product from the AD31 aluminum alloy the smooth fine-grained structure is formed with grains of 6 - 17 μm, which leads to an increase in the strength properties of the alloy and to a preservation of good plasticity.

Abstract: Technological parameters of receiving composites from Tetra Pak packaging waste are determined in the work. Physical - mechanical characteristics of the received composites are defined. The analysis of the received results showed that composites from Tetra Pak packaging waste have loose structure and lower strength properties, in comparison with cardboard. Introduction of polyvinyl acetate (PVA) suspension leads to an increase in density of composites and strength properties. Tensile strength increases by 1,9 times, but doesn't reach the level of tensile strength of cardboard composites. Application of hot pressing results in formation of denser composite, thus, tensile strength of a sample increases by 2,8 times. Cumulative effect of PVA glue and hot pressing leads to an increase of composite tensile strength by 5,9 times. It becomes significantly higher than the similar characteristic for a packing cardboard. According to the realized complete factorial (CF), the adequate regression equation was received. It shows that the strength of Tetra Pak wastes composites, in a greater degree, depends on the concentration of PVA suspension.

Abstract: Cellular glass composites can be made of waste flat glass or bottle glass added with eggshell powder 0, 1, 3 and 5%wt and then fired at 800° and 900°C for 1 h using compression molding process. Adding eggshell powder mixed with glass cullet affects to form open and closed pores and to decrease firing temperature, thermal expansion coefficient and light weight. However, adding high amount of eggshell powder affects to form an excessively amount of open and closed pores effect to increase water absorption. The standard Thailand Industries determines water absorption of glass foam less than 25% because high water absorption affects to decrease mechanical properties. Therefore, cellular glass composites added 1, 3 and 5%wt should not be fired at temperature higher than 800°C for 1h. In addition, the cellular glass composites added 1 %wt eggshell powder and fired at 900°C for 1 h still have low water absorption and low thermal expansion coefficient. Cellular glass composites are potential to apply for many industries such as construction, petroleum and petrochemical, insulation, medical and dental applications.

Abstract: Ecological construction has a tendency to increase. One of its directions is the straw bale-house. The safety of such buildings is based on increasing the fire resistance of pressed straw panels. In order to increase the fire resistance of such panels, they are plastered with a clay-lime mixture, treated with flame retardants and antipyrenes. The protective equipment effect on the fire resistance is not fully understood. Therefore, the work considers evaluation issues of the fire resistance in pressed straw building envelopes, depending on the plaster layer thickness, the straw pressing density and the flame retardants treatment. The study found that with a panel thickness of 450 mm, the straw density in the range of 110-140 kg/m³, clay plaster thickness of 30 mm ensure integrity, insulating and load-carrying capacity. The temperature on the panel rear side did not exceed 67 °C. The pressed straw density has almost no effect on the panel fire resistance. Antipyrenes treatment improves flammability from 18% to 37-42% that makes it possible to classify the samples as hardly combustible materials.

Abstract: The article presents the results of research on obtaining powder of hard alloy using various methods. The analysis of studies described in the literature. Currently, there are many ways to obtain powders from waste, but most of them are poorly applicable in practice in a particular plant. On the basis of the data obtained from the literature, a method of obtaining powder was selected, which can be used in an enterprise with the equipment available. Technological regimes were also selected, which included such operations as softening the workpieces, mechanical grinding, grinding the powder in a ball mill, making press powder, molding, sintering, and tool making processes. The resulting blanks were further compared with a standard tool for cutting edge resistance and the presence of external and internal defects. The work carried out has shown the possibility of using technological regimes for the production of powders on existing equipment for the subsequent manufacture of cutting tools. This technology allows to reduce costs and product cost without significant loss in product quality, which makes it possible to compete with other manufacturers of carbide tools. In the future, it is planned to develop and optimize the existing technology to improve product quality. The paper presents the results of research of obtaining a hard alloy powder with a different methods. Comparison of products from different powders and the subsequent pressing rods, their sintering and examination of defects

Abstract: The article touches upon the problem of raw materials for the ceramic industry. We have found alternative sources such as opoka-like rocks which are widely distributed in the South of Russia and the Volga region. The article presents the description of the characteristic features we identified in the process of compression molding opoka-like rocks of different types. The influence of compacting pressure on the density of pressed samples is given. There are conclusions about expediency of use of such raw materials for the development of ceramic industry.

Abstract: Ti and its alloys can deliver a very interesting combination of properties such as low density, high strength, corrosion resistance and biocompatibility and, therefore, are very flexible materials which can be adapted to various applications. Nonetheless, Ti and Ti alloys are only employed in critical applications (i.e. aeronautical and aerospace, nautical, medical, etc.) or in products for leisure. In both of these cases the higher fabrication costs of Ti in comparison to its competitors (i.e. steel and aluminium) is not the limiting factor as it is for many structural applications, especially for mass production (i.e. automotive sector). The use of creative techniques and the decrement of the starting price of Ti have been identified as the two main routes to follow to decrease the fabrication costs. In this study, the production of low-cost α+β Ti alloys has been assessed by combining the addition of cheap alloying elements (in particular a Fe/Ni powder) with the classical powder metallurgy route (pressing and sintering). Physical and mechanical properties as well as microstructural analysis of these low-cost alloys were measured and correlated to the processing parameters used to sinter them. It is found that the low-cost Ti alloys show similar behaviour to conventional α+β Ti alloys and, thus, have the potential to be used for non-critical applications.

Abstract: One-stage technology of obtaining aluminum-ceramic skeleton composites by combining the processes of self-propagating high-temperature synthesis (SHS) of the porous skeleton and its infiltration under pressure with molten aluminum (method SHS-pressing) was considered. Experimental study of the effect of the pressure of infiltration on the distribution of the content of aluminum over the height and radius of the disk-shaped sample with SHS skeleton made of a cermet of TiC-Ni was performed. Mechanisms of the formation of structure and properties of the composite depending on the infiltration pressure were described.

Abstract: There are the results of computer simulating using DEFORM-2D specialized software and experimental researches during the pressing of aluminium alloys tubes with conical-stepped needles. On the basis of the experiment mathematical planning and dividing coordinate grid the influence of the taper angle and needle position to the pressing stress and the intensity of deformation relative to the die parallel land was established. The optimal parameters determining methods of conical-stepped needles geometry were proposed.