Key Engineering Materials Vol. 822

Abstract: Selective Laser Sintering (SLS) is close to be accepted as a production technique (Additive Manufacturing). However, one problem limiting employment of SLS for additive manufacturing in a wide-ranging industrial scope is the narrow variety of applicable polymers.In the present work, a thermoplastic semi-crystalline polyimide powder was synthesized.. The shape, size and fractional composition of such powder were investigated by scanning electron microscopy. As a result, polyimide powders with a fairly narrow particle size distribution were formed. On the basis of the polyimide powder, samples were obtained in the form of films by the method of selective laser sintering (SLS). The mechanical properties of these samples were investigated depending on a laser energy density. The morphological study of the films cross-sections showed that monolithic sample having insignificant pores and irregularities in the structure was formed

Abstract: A series of unidirectional thermoplastic tapes (UD tapes) specimens based on carbon fibers and polyamide filled with fullerene soot in a concentration of up to 4 wt. % was made. A study of the tribological properties by the 3 Ball on Plate test and Ring on Plate test and was made. Shown that the introduction of fullerene soot up to 2 wt. % decreases scatter of CoF in both ranges of load and velocity. Also, this concentration decreases wear rate almost 2.5 times compare to unfilled specimen. Mechanism of friction and wear was suggested. The obtained tribological results are well consistent with mechanical properties, and agree with previously suggested theory of the effect of fullerene soot on adhesion between polymer and fibers.

Abstract: Poly (diethylene glycol) adipate diol, tolylene-2,4-diisocyanate, 1,3-bis (3',4-dicarboxylphenoxy) benzene and 1,4-bis (4'-aminophenoxy) biphenyl were used as monomers to form statistical copoly (urethane-imide) s with variable content of imide blocks (from 37 to 65% (wt)). The copolymers imide blocks on the T_g and T_m values relative content increasing effect was traced, which is associated with the phase separation of hard imide and flexible polyester blocks in the systems studied.

Abstract: We consider a silicon nanopowder based anode for a lithium ion battery cell. We present the design of the battery cell ready for in situ Raman and X-ray experiments and a technical procedure for the cell manufacturing. From the continuum mechanics point of view, this type of anode can be represented by a spherical nanoparticle surrounded by viscoelastic matrix. During the charging process this nanoparticle undergoes a chemical reaction. Based on the chemical affinity concept we describe how the mechanical properties of the matrix material influence the kinetics of the charging process. We study spherically symmetry problems numerically for different sets of matrix material parameters and show their influence on the reaction front kinetics.

Abstract: In this research developed the technique for the metal foam based on the Al-carbon nanotubes composite material. The optimal regimes for the samples foaming are proposed. The pilot samples were received. The behavior of the pores distribution in the samples volume is presented.

Abstract: Nd₂Fe₁₄B particles were obtained from mixture of neodymium oxide, iron oxide, boric acid and CaH₂ by reduction-diffusion process. Two different washing processes were used for the separation of magnetic particles from Ca and CaO matrix: usual washing with water and planetary ball milling process in ethanol media. Nd₂Fe₁₄BH_x hydrogenated state was formed after usual washing with water. Ethanol planetary ball milling washing procedure prevented the formation of Nd₂Fe₁₄B hydrides during washing. Variation of milling parameters allowed producing particles with different morphology such as spherical or flakes after planetary ball milling washing process. Influence of milling parameters on magnetic properties of Nd₂Fe₁₄B powder was investigated.

Abstract: The paper presents a new technological scheme for obtaining bimetallic materials of the composition "aluminum casting alloy - sintered iron powder" by the method of joint stamping. The results of experimental studies of the effect of process conditions on the physicomechanical properties of the starting materials and the adhesive strength of the final bimetal blank are presented.

Abstract: The consolidation process of agglomerated Cu – γ-Al₂O₃ composite nanopowder was investigated experimentally. Process includes powder compacting by uniaxial cold pressing, sintering in hydrogen atmosphere, and hot extrusion. The interdependence of alumina content, powder agglomeration, green density of compacts, and isothermal sintering behavior of powders was evaluated.

Abstract: The paper presents an information model and a general methodology for studying the electrophysical properties of materials and products from nanostructured composites. The information model of the original methodology for the standard process of experimental measurement and study of the electrophysical properties of composites comprehensively takes into account the characteristics associated with their industrial production (quality assurance systems, safety, certification, etc.) in order to develop experimental measurement methods and new standards, including standards of enterprises, methodological guidelines, work programs for the development of high-tech production advanced materials and products.

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