Papers by Keyword: Synthesis

Abstract: Carbonate hydroxyapatite is the common derivative of hydroxyapatite found in living systems. It is the building block of most hard tissues, including the teeth and bones. A vast majority of the applications of this versatile material focus on its biomedical applications, which is attributable to its closeness to biological apatites. Hydroxyapatite is a strong precursor to carbonate apatite in nature, and many experiments show that both are similar in a few respects. A significant divergence point is carbonate's obvious impact on its physicochemical properties and concomitant applications. The inclusion of carbonate ions into the lattice of hydroxyapatite results in morphological and physicochemical changes that vary with the method of synthesis and extent of substitution. The unique crystal structure, improved surface area, and porous morphology of carbonate hydroxyapatites also make it useful for catalysis and environmental remediation as adsorbents for heavy metals. This review briefly examines carbonate hydroxyapatite, its synthesis, its modification, and its characterization. It also highlights its biomedical applications while drawing attention to its non-medical potential.

Abstract: The main aim of this research was to investigate the effect of the addition of coal fly ash as a secondary waste material on the synthesis and properties of forsterite ceramics. The utilization of fly ash as a raw material, which contains flux oxides, reduce the necessary firing temperature for the synthesis of forsterite ceramics in comparison with forsterite ceramics synthetized from high purity or industrial materials, while preserving its refractory properties. The results revealed that forsterite was synthesized as a major crystalline phase in all samples. The optimal firing temperature for obtaining good physico-mechanical parameters was found to be between 1400-1600°C for high purity or industrial materials, while mixtures containing fly ash could achieve similar parameters at lower firing temperatures between 1200-1300°C. The decrease in refractoriness was found to be within acceptable limits for utilization as a refractory material. These findings demonstrate the potential for cost reduction and energy savings through the use of secondary waste materials and reduced firing temperature in the synthesis of forsterite ceramics.

Abstract: The article deals with the pulse electrolysis energy parameters effect on the current efficiency, phase composition and morphology of the cobalt with refractory metals – tungsten and molybdenum galvanic alloys surface. Synthesized coatings corrosion resistance and synthesized coatings catalytic activity testing results in various acidity media are presented. The obtained experimental data for the various composition alloy Co-Mo-W are compared with respective indicators for individual metals. The synergy effect presence due to the alloying elements mutual influence is experimentally established.

Abstract: Carbon nanotubes (CNTs) are nanostructures made from rolled graphene planes and have several intriguing chemical and physical characteristics. Allotropes of carbon having a nanostructure that can have a length-to-diameter ratio greater than 1,000,000 are known as carbon nanotubes (CNTs). These cylindrical carbon molecules have unique features that could make them valuable in a variety of nanotechnology applications. Their distinct surface area, stiffness, strength, and durability have generated a significant amount of interest in the health industry to achieve bio-functionalities, CNTs can be connected with a variety of biological substances, such as hormones, proteins, and nucleic acids. There are two types of CNTs: single-walled (SWNTs) and multi-walled (MWNTs). Their high aspect ratio, ultralightweight, strength, strong thermal conductivity, and electrical properties ranging from metallic to semiconducting are just a few of their intriguing characteristics. Drug delivery, blood cancer, breast cancer, brain cancer, liver cancer, cervical cancer, immunological treatment, biomedical imaging, biosensors, and tissue engineering are all areas where CNTs are beneficial, and the toxicology of carbon nanotubes is also discussed here.

Abstract: (1-x)BiFeO₃-xBaTiO₃-0.01KVO₃ with (x = 0.33 and 0.38) (abbreviated FTV33 and FTV38) was successfully prepared using three precursors that had been synthesized before the calcination process. BaTiO₃ was synthesized using the coprecipitation method, BiFeO₃ was synthesized using the sol-gel auto-combustion method, and KVO₃ was synthesized using the conventional solid-state method. Thermal analysis was carried out to determine the calcination temperature from 600 0C for 2h to 600 0C for 4h. X-ray diffraction (XRD) has been carried out to identify the phase after calcination at temperatures, respectively. The phase identification of the XRD pattern has been carried out by Match software shows that the powder and FTV33 and FTV38 have a pseudo-cubic structure with a P4mm space group and rhombohedral with an R3c space group. The XRD pattern is refined by the Rietveld method by Rietica software and the crystalline size is determined by MAUD software. The doping effect of KVO₃ on its electrical properties was systematically investigated and show that FTV33 is more conductive and has larger capacitance grains. Based on the previous XRD analysis, Ba²⁺ and K⁺ ions replaced Bi³⁺ at site A. On the other hand, Ti⁴⁺ and V⁵⁺ substituted Fe³⁺ at site B which was different from the host's oxidation state.

Abstract: A study was carried out on the effect of hydrochloric acid (HCl) temperature and molarity during the dissolution process on the crystal cell of ZrSiO₄ of zircon powders derived from zircon sand mined in Kereng Pangi, Central Kalimantan. The study is a continuation of the previous work and is aimed at associating the process and structural parameters of the zircon phase in the product. The synthesis was started with a well-established route in our laboratory, i.e., magnetic separation and milling for 2 hours, but the subsequent leaching using the HCl step was carried out at varying temperatures and concentrations. The temperature variations used were 80°C, 90°C, and 100°C, while the molar variations of HCl were 0.5 and 2 M. Then, the various products were further leached using 7 M sodium hydroxide (NaOH) to yield zircon powders subjected to X-ray diffraction (XRD) investigation. The XRD data analysis using Rietica software found that at the concentration of 0.5 M, the increasing temperature decreased in zircon cell volume but increased the tetragonality parameter c/a. However, opposite results occurred at the concentration of 2 M HCl. In general, we found that the impurity levels in the zircon powders may be associated with its cell volume and tetragonality parameters, i.e., the more the quartz content in the zircon powder, the smaller the zircon cell volume and tetragonality.

Abstract: The research objective is to simplify the method for estimating the density of straight-run hydrotreated winter diesel fuel (HTDFWs). The density of straight-run hydrotreated winter diesel fuel is one of the quality indicators ultimately determining the density of winter diesel fuel and therefore, the quality of winter diesel fuel in terms of density. Problems: to describe the current methodology for estimating the HTDFWs’ density, isolate the cycles, and express the cycles by formulas. Research methods – analysis, synthesis, comparison, mathematical analysis. As a result, simplified density calculation with expressing cycles by formulas has been proposed. A mathematical model has been obtained to estimate the density of straight-run hydrotreated winter diesel fuel.

Abstract: The volumetric changes and variable porosity due to the concentration expansion of the solid phase in the synthesis of zirconium nitride (ZrN) are studied. The model of two-stage reactor based on spark plasma sintering (SPS) is proposed. At the first stage the synthesis for the given kinetics is simulated. At the second stage the densification of ZrN using the Olevsky’s sintering model [1-5] is applied. The synthesis and densification processes using the prescribed heat sources, at the given positions inside the reactor is simulated. The generalization of the two-temperature model [6] and the formula of the porosity in the densification using calculation of the solid concentration expansion and thermal dispersion is proposed. The concentration expansion coefficients in the process of zirconium nitrogenating at a given initial density values and coefficients of expansion of reagents .is studied The temperature at the stage of ZrN synthesis and porosity variation at the stage of densification are in satisfactory agreement with experimental results [2,7,8]

Abstract: A new method for obtaining submicron hard alloys based on sintered tungsten carbide with cobalt by joint low-temperature carbothermic synthesis in vacuum has been developed. The compositions of the initial components for the synthesis of powders of the composition WC-6%Co and WC-10%Co are calculated. The main component for the synthesis of submicron tungsten carbide powders is tungsten oxide WO_2.9, obtained by reducing α-tungsten oxide WO₃ in a hydrogen medium at a temperature of 500-550 °C. The powders obtained by synthesis are characterized by high hardness values (up to 94 HRA). Cutting tests of replaceable polyhedral plates made from the obtained powders for processing a heat-resistant alloy have shown satisfactory results. The microstructure of the alloys was analyzed using scanning electron microscopy.

Abstract: Silica nanocapsules (SiNC) utilization as adsorbent in pollution control have gained much attraction as SiNC are highly porous, have high surface area, excellent thermal and mechanical stability and a tuneable physicochemical property. In this study, microemulsion technique was used to synthesized SiNC. Effect of stirring rate as well as the effect of different method of amine functionalization i.e. grafting, wet impregnation, co-condensation, on the physicochemical properties of SiNC were studied. The stirring rate have significant effect on the physical properties of the SiNC. As the stirring speed increased from 200 rpm to 600 rpm, the particle diameter and the surface area decreases, 695 to 600 nm and 773 to 654 m²/g, respectively. The SEM and TEM analysis shows higher stirring rate produced surface with extensive damage while lower stirring rate produced a smoother surface. Different functionalization method affected the amount of amine groups incorporated into the SiNC. The FTIR spectra shows that the impregnation method incorporates higher amount of amine as indicated by the higher peak transmissions in the region 3450 – 3250 cm^-1. However, amine functionalization of SiNC resulted in decrease of surface area as surface pore of the SiNC were occupied by the amine moieties’ molecules. The optimum condition for synthesizing amine functionalized SiNC were determined to be at stirring rate of 450 rpm through wet impregnation method as the SiNC produced were of spherical shape with smooth surface, and a relatively high surface area of 695 m2/g and pore diameter of 601 nm. These physicochemical characteristics shows the synthesized amine functionalized SiNC have promising qualities for application as adsorbents.