Papers by Keyword: Calcium

Abstract: Magnesium aluminium of the magnesium-alloy variety have long been extensively utilized in different technical applications and are still capturing the attention of researchers because of their cost-effectiveness and lightness. Grain fractal sizes, microstructural relationships, and sphericity, as well as their relationship with service performance, were discovered for numerous frequently employed Mg-Al alloys. As a result, the influence of cow’s bone extracts calcium on the mechanical behaviours as well as microstructure of Magnesium aluminium alloy was investigated in this work. Calcium (0.5% weight) concentration, formations with uniform and non-uniform grain boundaries led to alloy hardening. 286.537MPa and 57.3 HB are respectively the highest tensile strength and hardness gotten.

Abstract: For the first time, the time dependences of the temperature of aluminum, zinc and zinc-aluminum alloys alloyed with II A group elements under spontaneous cooling mode were obtained; an anomalous course and two characteristic times of the cooling process were found, and their mechanism was explained; the temperature dependence of the thermophysical properties of the investigated metals and alloys was established; the temperature dependence of the coefficients of convective heat transfer and radiation of Al, Zn and Zn55Al and Zn5Al alloys was experimentally determined; the influence of the concentration of II A group elements and temperature on the heat capacity and thermodynamic functions of Zn55Al and Zn5Al alloys was revealed.

Abstract: In this article the conventional "solid-state reaction" method was used to synthesize perovskite Li_0.4Cd_0.6Ba₂Ca₂Cu₃O_10+δ. Four main types of compounds were obtained by physically replacing calcium oxide with cadmium in proportions 0, 0.03, 0.06 and 0.09, the pure Li_0.4Cd_0.6Ba₂Ca₂Cu₃O_10+δ phase, and the phases Li_0.4Cd_0.6Ba₂Ca_1.97Cd_0.03Cu₃O_10+δ and Li_0.4Cd_0.6Ba₂Ca_1.94Cd_0.06Cu₃O_10+δ and Li_0.4Cd_0.6Ba₂Ca_1.91Cd_0.09Cu₃O_10+δ ,respectively from mixing their constituent oxides and pressed into pelts and then sintered in the furnace at 850 degrees Celsius for 90 hours: These samples have been studied for their original dielectrically properties. The real dielectric constant, dielectric loss factor, and tangent were calculated in the frequency range (50 to 1000000 HZ). It was found that the partial substitution of cadmium oxide plays an important role in enhancing dielectrically properties.

Abstract: Error reasons of gold analytical determination in the chemical plant sludge are studied. The studied sludge is waste of BaCl₂ production. According to preliminary estimates it contains gold in sufficient quantity for industrial extraction. Comparison of direct sludge fire assay analysis and sludge dissolution in aqua regia, followed by gold atomic absorption determination in solution is made. The negative effect of Na⁺, Ca²⁺, Ba²⁺, Zn²⁺ ions presence in studied solutions was shown. Error quantitative estimate at alkali metals introducing into standard solutions is given. It is shown that Ca²⁺ and Ba²⁺ ions contribute the most error. Error increases linearly at addition of Ca²⁺ and Ba²⁺ ions. Growth error gradually slow down at increasing Na⁺, Zn²⁺ ion content.

Abstract: Zinc and magnesium alloys are considered to be suitable for application in medicine as materials for biodegradable implants such as fixation devices for bone fractures. Lower corrosion rate and no release of hydrogen during an exposition in corrosion environment make the zinc alloys more suitable for this application from the corrosion point of view. On the contrary, the daily acceptable dose of Zn for the human organism is much lower compared to the Mg. The present paper is focused on the comparison of Zn-1.5Mg, Zn-1.5Mg-0.5Ca, and WE43 alloys. Both alloys were processed by extrusion in order to improve mechanical properties. The tensile yield strengths of 308 MPa and 280 MPa were measured for Zn-1.5Mg and WE43 alloys respectively. The corrosion rates were almost similar for zinc-based alloys and WE43.

Abstract: The largest comparison of analytical techniques, useful for calcium phosphates, has been conducted, presenting recommendations for quality control and research of calcium phosphates. Results from three classical quantification methods (gravimetry, titramety, photometry) and three instrumental measurement methods (XRF, FAAS ICP-OES) are reported to determine the most accurate, fastest and cheapest analysis method. Remarks are given for increasing the accuracy for each method and corrections made for adsorbed water. For routine analysis, a recommendation is given to ICP-OES for a fast analysis, together with a less frequent use of gravimetry to validate the results and provide a periodic cross-check.

Abstract: A method for calculation of the diagrams of steel deoxidation and modification by calcium, magnesium, aluminum and boron was developed. The coordinates of the liquidus surfaces of the oxide systems B₂O₃–Al₂O₃–MgO, B₂O₃–Al₂O₃–CaO, B₂O₃–MgO–CaO were found at 1873 K. The energy parameters were determined for the theory of subregular ionic solutions of the studied oxide systems. The coordinates of the solubility surfaces for the systems Fe–Mg–Al–B–O, Fe–Ca–Al–B–O, Fe–Mg–Ca–Al–B–O were calculated. The effect of the total pressure on solubility of magnesium and calcium in liquid iron was studied. The activity of the components of the metallic melt was calculated using the first-order interaction parameters (Wagner's theory). The activities of the components of solid solutions (oxides and spinels) were equated with their molar fractions. It was shown that during extensive refining of metal from the oxygen, only a small fraction of boron oxidizes and these oxides form fraction of the oxide melts. The major non-metallic oxide inclusions were magnesia spinel, calcium bialuminate and liquid oxide formations. The "free" boron was dissolved in liquid metal in amounts which were in equilibrium with oxide phases.

Abstract: In the general balance of water consumption, a considerable part falls on softened water. The processes of obtaining softened water form a significant amount of liquid waste containing calcium and magnesium salts. We show the possibility of using wastewater from water softening installations for the treatment of wastewater containing dyes. The obtained results demonstrate high efficiency of wastewater treatment in textile factories. An additional advantage of the use of sewage water softening plants is the economy of reagents for the removal of dyes.

Abstract: The Mg-1wt.%Ca alloy was fabricated using powder metallurgy method. The anodizing process were done by using different voltage (5V, 15V, 25V) and concentration of KOH (0.1M, 0.5M, 1.0M). The surface changes on PM Mg/1wt.%Ca resulted by anodizing was analyzed using SEM-EDX and XRD pattern. Meanwhile, surface hardness was measured by micro-Vickers hardness machine. The experiment found different XRD pattern between all non-anodized and anodized samples. The study found that increasing the voltage will increase the hardness while increasing KOH concentration reduced the hardness. The relation of the hardness and oxide film formation can be analyzed using SEM-EDX and XRD pattern. The optimum value for voltage, KOH concentration and hardness are 25V, 0.1M and 27.2 HV. The XRD detect the changes in PM Mg/1wt.% Ca indicates the oxide film formation.

Abstract: Long–lived ¹³⁴Cs and ¹³⁷Cs isotopes with half-cycle of 2.06 and 30 years respectively refer to the most dangerous and wide-spread radionuclides in ecological facilities. The efficient way of removing cesium radioisotopes from the living environment is to bind them into the compounds insoluble in water. This paper presents the findings on the sorption properties of synthetic nanostructured calcium aluminosilicates (CAS) with AI:Si correlation equal to 2:2, 2:6, 2:10 and obtained in CaCI₂—AICI₃—КОН--SiO₂—H₂O multiple-component system. An isotherm investigation of cesium ion sorption produced from aqueous solution with Cs+1 from 0.2 till 6.0 mmol/L-1 concentration was carried out. Maximum sorption capacity of calcium aluminosilicates (CAS) as well as Langmuir constant was defined. The kinetics data was received and the activation energy of cation exchange in the process of sorption was estimated. The impact of 1% КCI + 6% NaCI saline background on the values of interfacial distribution coefficient (Kd) and recovery rate of cesium ions were determined.