Papers by Keyword: Composition

Abstract: Ideal physical and mechanical properties and lightweight materials are the main requirements in today's transportation and automotive industries. This research aims to determine variations in Mg composition and sintering temperature of aluminum matrix composites using moulds with a powder metallurgy process on the properties and microstructure of the composite. Magnesium particles with a size of 250 μm were added to the Al-Cu-Mg-matrix at different volume ratios (1%, 1.5%). The mixture of Al, Mg, and reinforcement (Cu, ) powder was mixed at 1,500 rpm for 2 hours for homogeneous dispersion. The mixed powder is compacted at 200 MPa and sintered at different temperatures (500°C, 550°C, 600°C) and then allowed to cool slowly in the furnace. Composite character research was then done by testing density using the Archimedes principle, porosity, microhardness, wear rate, SEM characterization, quantitative analysis and EDS mapping. The optimal composite condition is characterized by a relative density of 57.45%, the lowest porosity ratio measured at 7.48%, a microhardness level of 52.1 HV and the lowest wear rate of 0.58 /m in the Al-Cu-Alumina composite with the addition of 1.5% Mg and sintered at a temperature of 600°C. This composite character is supported by the results of microstructure observations using SEM-EDS. The use of micro-in the Al-Cu-Mg composite supports the optimization of physical and mechanical characteristics as a composite worthy of being considered as the material of choice for components of transportation and automotive modes.

Abstract: The chemical composition of the metal and carbide phase, hardness, and common mechanical properties of cast iron, ICH28H2 cast iron, a type of high-chromium white cast iron, and the dependence of hardening, annealing, and tempering process types were studied. Therefore, annealing and hardening heat treatments were employed, and the results were compared to measurements in the as-cast state. The metal matrix exhibited content within the range of 16.8% to 19.7% Cr and 71.9% to 76% Fe, while the carbide phase showed 63.4% to 64.7% Cr and 23% to 24.8% Fe. The Cr carbide in high Cr white iron primarily appeared as (Fe, Cr)7C3 type, leading to the calculated chemical formula of the eutectic carbide as (Fe2Cr5)C3. The as-cast white iron displayed a hardness of 53 HRC, which increased marginally to 56.2 HRC after hardening. This suggests that the 28% Cr white iron alloy does not exhibit a significant hardness enhancement compared to the cast state, attributed to its high Cr content. The hardness of the metal phase directly influences the overall hardness change of the alloy, while the carbide hardness is dependent on its Cr content. Abrasive wear studies revealed that 28% Cr white cast iron exhibited superior wear resistance in the as-cast state compared to the hardened state, aligning with research indicating that cast iron demonstrates optimal wear resistance in its cast state.

Abstract: Chitosan-Kappa Carrageenan (Chit-KC) hydrogel films have been made using a casting method with different compositions. This research aimed to investigate the effects of different compositions on the chemical, physical, and mechanical characteristics of the Chit-KC hydrogel films. The compositions of the kappa carrageenan in the Chit-KC films were 0%, 16.67%, 33.33%, 50.0%, and 100.0%. The films were characterized using FTIR, SEM, DTA-TGA, and XRD instruments to analyze their functional groups, morphology, thermal properties, and crystallinity. They were also tested for their solubility, swelling, water vapor permeability (WVP), and mechanical characteristics. The results revealed that the addition of kappa-carrageenan induced the formation of a polyelectrolyte complex. The polyelectrolyte complex caused an increase in swelling, crystallinity, and WVP values and a decrease in solubility, tensile strength, elongation, and elasticity. It also caused the formation of film layers and granules on the surface of the hydrogel film. The IR spectra exhibited that the Chit-KC hydrogel films contained O-H, C-H, C=O, S=O, C-O, and C-O-C groups. The DTA-TGA test results revealed that the film began decomposing at around 200°C and re-decomposing at 300°C.

Abstract: Проаналізовано вітчизняні та зарубіжні вогнегасні покриття та особливості їх використання як елементів пасивного та активного вогнезахисту з матеріалами, що спучуються, а також оцінено доцільність їх застосування для будівельних конструкцій з металевими елементами для підвищення вогнестійкості будівлі та споруди промислового сектору. Отримано залежності, які дають змогу прогнозувати безпечний час перебування людей всередині об’єкта до обвалення будівельних конструкцій у разі виникнення пожежі. Розглядалися можливості виробництва з використанням ряду недорогих композицій, які набухають і підвищують вогнестійкість будівель з металевими елементами за рахунок набухання та адгезії до горючих поверхонь металоконструкцій. Були проведені експерименти для отримання даних про можливість безпечного перебування людей всередині будівлі або споруди до їх руйнування. Встановлено, що набухання та зчеплення з поверхнями металевих конструкцій дозволяють підвищити пожежну безпеку особового складу пожежно-рятувальних та інших служб, залучених до ліквідації таких надзвичайних ситуацій.

Abstract: Photocatalyst activity relates to the active surface area between pollutants and catalyst compounds. The insertion of Al atoms as a substantial defect in ZnO structures can reduce the particle size thus the active surface area increases. Another way to raise the photocatalytic activity of ZnO is by combination with other oxide materials such as TiO₂ (Titanium dioxide). In this study, the ZnO-Al:TiO₂ powder was successfully prepared via the sol-gel method using zinc acetate dihydrate as a precursor, 0.5wt% of aluminum nitrate nonahydrate as a dopant precursor, and TiO₂ anatase. In order to understand the role of the combination of these two metal oxides, the concentration ratio of ZnO-Al and TiO₂ was varied by 1:1 (ZAT) and 4:1 (ZA4T) under low (150°C) and high (450°C) temperature calcination. Photocatalytic testing was carried out using a 3.2 ppm methylene blue (MB) solution under UV-A lamp irradiation for 120 minutes. The high calcination temperature facilitates the growth of ZnO-Al. Besides that, the different ratio concentrations and calcination temperatures produce different defect states in each sample. The most optimum results in the photocatalytic activity performed by ZnO-Al:TiO₂ 150°C (ZAT 15) with degradation rate constant (k) of 0.033/min and efficiency of 97% for MB removal. The unexpected zinc vacancies defect is estimated produce at the samples in high-temperature calcination. This defect type can accelerate electron-hole pair recombination. In Addition, samples with high-temperature calcination were considered to have lower hydroxyl/oxygen bonds on the surface thus affecting the photocatalytic performance.

Abstract: Research on improving petroleum bitumen complex properties by modifying them with polymeric elastomers in the form of rubber waste are given in this article. The purpose of the research is to create a bituminous-rubber composition with an increased set of thermo-physical and physical-mechanical characteristics. The effect of bitumen modification with waste rubber crumb and powder in combination with the addition of taurite on the melting temperature, the degree of crosslinking, toughness and heat resistance of the compositions was studied. The optimal composition of bituminous-rubber compositions modified with taurite with high thermo-physical and physical-mechanical characteristics has been determined.

Abstract: In this article are presented the results of X-ray and IR spectroscopic studies of the structure of the atmosphere - and chemically resistant composite materials based on medium density polyethylene. The presence of specific interactions with polyethylene ingredients in composite materials. It has revealed the appearance on the surface of the active radicals that promote increased interaction fillers with polyolefins, as well as the increase of the elastic-strength characteristics of composite materials are revealed.

Abstract: The results of thermodynamic simulation of the manganese recovery in the CaO-SiO₂-MgO-Al₂O₃-MnO-Fe₂O₃ system by carbon are presented. Parameters of the initial system are temperature range 1400-at a step of , a total pressure of 0.1 MPa, and N₂. The composition of the oxide system is corresponded by the manganese ore (wt %) 1.1 MnO₂, 44.3 MnO, 28.4 CaO, 9.3 SiO₂, 5.4 MgO, 0.3 Al₂O₃, 11.2 Fe₂O₃ and silicomanganese slag. It contains (wt %) 16.3 MnO, 18.4 CaO, 52 SiO₂, 7.8 MgO, 5.26 Al₂O₃, and 0.24 FeO. The amount of silicomanganese slag in the system was 0, 5, 12, and 25%. Carbon is used as a reducing agent. Its consumption is increased by 5% from the stoichiometry for the recovery of Fe and Mn and by 8% of the metal mass for the formation of iron, manganese, and silicon carbides. The simulation is carried out using HSC Chemistry 6.12 () software package. The thermodynamic characteristics of the Fe₃C, Fe₂O₃, FeO, MnO₂, Mn, Mn₃C, Mn₅C₂, Mn₇C₃, Mn₂₃C₆, and SiC compounds existing in the database are refined. It was determined that an increase in the melt temperature from 1400 to increases the degree of manganese recovery (η_Mn) for all compositions of the systems. An increase of the silicomanganese slag content in the mixture from 0 to 25% decreases η_Mn from 89.3 to 85% at and from 95.8 to 91.5% at . The chemical composition of the high-carbon ferromanganese alloy is (wt %): 71.9-72.8 Mn, 16.6-17.9 Fe, 0.015-1.64 Si, and 9-. The simulation results can be used to develop a technology for producing a high-carbon ferromanganese when silicomanganese slag is involved in metallurgical processing.

Abstract: High Strength Concretes (HSC) are concretes defined mainly by compressive strength. The strength of concrete can guarantee other excellent results of properties, namely durability. Essential for the production of HSC is a careful approach to the design of concrete composition, especially the quality of raw materials. It is primarily necessary to increase the content of the binder combined mainly with Portland cement and another admixture. Due to its excellent properties, Silica fume is largely used as an admixture, where it is necessary to consider its effective amount. It is also suitable to combine this admixture with other types of active admixtures. The question of the type of coarse aggregate fractions used is crucial. The quality and purity of aggregates is an essential part of the quality design of these concretes, influencing practically all the resulting parameters of concrete. The article presents a set of tests on designed High strength Concretes, differing in the composition of the concrete to demonstrate the variability of the design concept and its effect on the resulting values of strength and durability.

Abstract: Based on magnesium carbonate and antimony oxide (V), MgO•Sb₂O₅ was obtained. In the formulation of fire-resistant cable PVC-plasticate, antimony (III) oxide was replaced by MgO•Sb₂O₅ and the fire resistance and physical and mechanical properties of the resulting compound were investigated. It is shown that the replacement of antimony (III) oxide in the composition of PVC cable compound MgO•Sb₂O₅ leads to the production of a compound that is not inferior in its characteristics to the original plastic compound. In particular, the fire resistance of cable PVC-plasticate, standard industrial formulation and with the obtained MgO•Sb₂O₅, is practically the same (OI=32%). It has been established that the physical and mechanical characteristics of the cable compound, when replacing antimony oxide (III) with MgO•Sb₂O₅ in the formulation, remain at the level of the original compound, while MgO×Sb₂O₅ will have a less negative impact on the environment.