Materials Science Forum Vol. 1006

Abstract: The theoretical model of air purification in the filter-absorber by means of the course of the adsorption process is considered in the article, attention is paid to the concept of "protective action". The defining role in the purification of air is played by adsorbents, which fill the absorber filters. Electron scanning microscopy and low-temperature nitrogen adsorption were used to study the adsorption properties of adsorbents and to show their different natural origin. Based on the obtained adsorption characteristics of the adsorbents, the conclusions about the protective action of the filter-absorber were made.

Abstract: The physic-mechanical properties of filled composites based on secondary polypropylene are investigated. As fillers the dispersed wastes of processing of agricultural plants - buckwheat and oat husk, as well as needles flour and wood flour were used. Water absorption, abrasion, impact strength and bending strength of composites were investigated. It has been proven that oat and buckwheat husks can be effectively used in composites based on secondary polypropylene and replace traditional wood fillers. It has been shown that the physic-chemical properties of the filled composites depend on the structure and physicochemical interactions on the phase separation surface, as well as on the surface properties of the filler particles. It is established that for the production of filled composites with improved physic-mechanical characteristics it is necessary to use fillers with small specific surface and concentration of surface functional groups, and the acid-base characteristic of the surface should be closer to neutral. It is shown that these conditions provide for the formation of a uniform structure of the filled composite with less internal stresses.

Abstract: Established the possibility of galvanochemical obtaining of a plating stronger than in case of chrome precipitation. Proposed precipitation of ternary alloy Co-Мо-W, which allows using the effect of synergism. Proposed and researched usage instead of sulphate-anhydride electrolyte – citrate-diphosphate and ammonia-citrate one. Achieved an increase in current efficiency of precipitated alloy and decrease in current efficiency of hydrogen, with respect to chrome precipitation, which increased safety of the galvanochemical industry. Selected the optimal ratios of components in citrate-diphosphate and ammonia-citrate electrolytes for ternary alloy Co-Мо-W precipitation. Determined the parameters of electrical effect for the galvanic process: constant current – j = 2–8 А/dm², pulse unipolar current – j = 4–20 А/дм². Achieved a high microhardness of this plating and high adhesion to base surface. Achieved greater safety of the galvanochemical technological process of ternary alloy Co-Мо-W application compared with chromium plating.

Abstract: In an article, studies of tin dioxide films for challenging sensitive elements of gas sensors for monitoring gaseous impurities in air have been described. The technological influence issues parameters of the process producing of tin dioxide films by magnetron sputtering at a fixed magnetron power on their crystal structure and phase composition were considered. The substrate temperature, layer thickness, and oxygen concentration in the atomized gas were considered as parameters. The foundation for improving the constructive and technological solutions of film gas sensors based on the research results was laid.

Abstract: Results of the development of a method for immobilizing nanosized palladium into an electrochemically synthesized polyaniline (PAn) electrically conductive porous matrix to create a sensitive element of an ignition sensor are presented. Two methods of manufacturing a sensitive element in the form of an electrode are investigated. The first method consists in the co-precipitation of polyaniline and palladium on a graphitized butyl rubber substrate in a mode of cycling of potential. It was shown that this method can be used to obtain a volume-porous electrode in which palladium nanoparticles are embedded in a polyaniline matrix. The second method involves the deposition of palladium on a polyaniline film formed on graphitized butyl rubber. It was shown that micron-sized island palladium conglomerates on the surface of a polyaniline film can be obtained by this method. The conclusions made are confirmed by physical research methods and the results of scanning electron microscopy. Investigations of the electrocatalytic properties of the electrode in the sensor model showed that with a change in the H₂ concentration formed upon ignition, occurs change in the hydrogen concentration on the surface of metal-catalyst (Pd) and a linear change in the current of electrochemical reaction. Comparison of a composite volume-porous polyaniline electrode with embedded palladium showed its superior efficiency compared to a compact palladium electrode and an electrode in which palladium is deposited on the surface of a polyaniline film. The possibility of using an electrochemical detector based on polyaniline with immobilized palladium nanoparticles for a gas amperometric sensor of low hydrogen concentrations and a fire hazard detector is shown.

Abstract: Orthopedic treatment of tooth anomalies in children and adolescents is provided the long-term use of various metal constructions and devices in the oral cavity – braces, retreaders, locks or rings with struts, wire arches, and so on. They are usually made of corrosion-resistant metals and alloys, most often they are made of stainless chromium-nickel austenitic steels of Х18Н9Т type (import analogue – steel 304), martensitic 08Х17 (import analogue – steel 430), nickel-titanium or nickel-molybdenum alloys. The main disadvantage of all metal products is their manifestation of electrochemical properties and participation in electrochemical processes which can flow into the oral cavity and provoke galvanoses, especially for their joint use. In the "in vitro" conditions, according to a specially developed method, investigations of electrode potentials of directly 4 types of very small (2–3 mm) orthodontic products, in recommended for such products environment were carried out: 3 % solution of sodium chloride (pH=6,8), 2 % solution of citric acid (pH=0.5) and 2 % solution of baking soda (pH=8.65). It is found that the considered elements of orthodynamic systems have similar values of electrode potentials in neutral and weakly-alkaline environments and, accordingly, in the absence of other metal inclusions in the oral cavity, can be used jointly without the risk of galvanosis. The most heterogeneous construction is an individual ring with a strut, in which the difference in the values of the potentials between the individual parts in the acidic medium is more than 120 mV, which is a prerequisite for increasing the likelihood of galvanosis. For simultaneous use of other elements, in particular standard doping brackets, the value of EMF can increase up to 160 mV.

Abstract: The ways of using coffee grounds as fillers for biodegradable polymer material and dishes from it is shown. Research of chemical, physical, mechanical and operational properties of new high-filler composite based on polylactide are carried out. It is also noticed, that using coffee grounds as fillers for polymer materials can decrease the total volume of it at landfills faster than any other method of coffee ground reuse.

Abstract: The methods of obtaining the base layers of cadmium telluride to create effective solar cells are considered. At present, two groups of methods are distinguished for the preparation of base layers of cadmium telluride for high-efficiency PECs: low-temperature and high-temperature. If a polyimide film with a temperature stability of 450 °C is used as a substrate, then deposition should be carried out at a temperature of about 430 °C. Therefore, to create base layers of cadmium telluride on a flexible polyimide substrate, it is necessary to use low-temperature methods for producing base layers. It has been established that the formation of base layers of solar cells based on cadmium telluride on flexible polyimide substrates must be carried out by direct current magnetron sputtering.

Abstract: In scientific work is presented the solution of scientific and practical task – the development and evaluation of the possibility of using difficult combustible epoxyurethane (EU) mastic with increased vibration-damping properties and the necessary physical and mechanical properties for cladding the internal metal surfaces of railway rolling stock bodies. The compositions of the developed mastic based on the mixture of oligester cyclo-cab (OCC) and epoxidian (ED) oligomers with the addition of flame retardant – ammonium polyphosphate (APh), as well as hydrophobic filler methylaerosil AM-1-300 to give the composition thixotropic properties. As a result of dynamic-mechanical and viscoelastic researches, it was found that the mastic composition ED: OCC with the content of fire-retardant additive and thixotropic filler has high damping properties (tgδ = 0.45-0.47) in highly elastic field, and therefore, from practical point of view, this the material can work both at low (from -60°C) and moderate temperatures (to +60°C). A comprehensive fire hazard assessment showed that the developed mastic belongs to the group of difficult combustible and difficult flammable materials with slow flame spread and moderate smoke generating ability, as well as moderately hazardous in terms of toxicity. The achieved level of characteristics of the difficult combustible vibration damping mastic testifies about the prospects of its further use for facing the internal metal surfaces of bodies of railway rolling stock in order to ensure their fire safety and acoustic comfort.