Papers by Keyword: Precursor

Abstract: This work identifies the effect of loading benzotriazole (BTA) on mesoporous silica nanoparticles (MSN) as an initial step in preparing a self-healing corrosion-protective coating with environmentally friendly precursors, rice husk, which advantages cheaper, renewable, and contains relatively high silica. This research uses the sol-gel method to synthesize MSN. Based on the result, it is known that the loading of BTA strongly affects the porosity properties of these nanoparticles. The pore sizes increase as the surface areas and pore volumes decrease. However, the silicone composition shrinks. Based on pore size, it is known that all the samples in this work were mesoporous materials (over 2 nm) with spherical and globular morphologies (like coral reefs).

Abstract: A two-stage hydrothermal method was used to prepare rapid-switching electrochromic WO₃/ZnO composite electrodes. The morphology of the nanorods was altered by changing the precursor concentration. A higher precursor concentration inhibited the growth of crystals and declined the crystallinity of nanorods. Nanorods with a diameter of 48 nm, height of 92.5 nm, and transmittance greater than 80% were grown when the precursor concentration in the second step was 1.5 times that in the first step. The electrochromic electrode demonstrated rapid coloring and bleaching speeds (5 and 0.8 s, respectively), which were faster than those of the electrode prepared using the one-stage process.

Abstract: In this paper, the influence of the precursors of nickel oxide (NiO) on the properties of ZnO/NiO nanocomposites thin films, grown by spray pyrolysis method, has been investigated. The nickel sulfate, nickel chloride and nickel nitrate have been used as precursors of NiO, each precursor has been mixed with Zinc oxide (ZnO)’ precursor to elaborate ZnO/NiO nanocomposites thin films with the method mentioned above. The aim of this paper is to confirm the similitude of precursors in the nanocomposites. For this reason, and to reveal this goal, some techniques were used as the structural analysis by X-ray diffraction (XRD) which a high intensity has been detected corresponds to the ZnO / NiO films with nickel chloride precursor, UV-Visible characterization depicts the presence of a maximum adsorption band appears in the ultraviolet range, the morphological characterization with Atomic Force Microscopy (AFM) reveals the roughness and the different grain size of particles, the big one of the latter agree, also, with to nickel chloride precursor used. The values of optical band gaps E_g are globally equal with high value noticeable agree with films that prepared with nickel chloride and zinc chloride precursors. The results obtained confirm the aim and a good agreement with the latter were found.

Abstract: Composites material were developed to acquire the desired material properties for biomedical applications in the recovery of defect bone by using Mg-doped HA/SA. Hydroxyapatite (HA) is the major constituent and essential component in bone and teeth. The stability of Mg doped HA/SA is influenced by starting precursor powders, preparation condition and method of preparing the samples for implant materials. The precipitation method was employed to prepare Mg-doped HA/SA powders by varying the composition of Mg at temperature 1300 C. The influence of Mg-doped HA/SA on phase composition, chemical structure and a functional group at various weight percentages (0.5wt%-1.5wt %) were accomplished through X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analyses. Based on the XRD and FTIR analyses, there is the presence of different peaks intensity and adsorption bands which indicates the shifted of peaks due to the doping process and a chemical interaction were observed between the inorganic and organic phase. Furthermore, the transformation of β-TCP due to increase in sintering temperatures are caused by the presence of magnesium ions. The OH stretching bands of HA/SA are trace by FTIR that identified the decomposition of Mg-doped HA/SA.

Abstract: In this paper, the extruded precursors were prepared by Powder compact method (PCM),with two different powder AlSi10 or pure Al mixed foaming agent ZrH₂ or TiH₂, then they were foamed to fill the hollow part. L9 (3³) orthogonal test was planned, including three factors, furnace temperature; foaming time; and arrangement mode. The results indicated that the pore structure were effectively improved through adjusting the arrangement mode of precursors. The specimens have been obtained the homogeneous foam expansion when the AlSi10-TiH₂ agent were arranged on the top while AlSi10-ZrH₂ agent precursors at the bottom in the hollow, and foamed 14 min~16 min at 800 °C

Abstract: Polycarborane, as a kind of boron carbide polymeric precursor, was synthesized by hydroboration reaction with styrene, divinylbenzene as the carbon resource and borane as the boron resource in this work. The polymer precursor which had good solubility and film-forming ability was soluble in most organic solvents. Furthermore, polycarborane was used to fabricate hollow polymer microspheres by emulsion technique. The compact boron carbide ceramic hollow microspheres were prepared by ceramization of the polymer microspheres. Ceramic microspheres with diameters ranging from 1 to 1.5 mm and shell thicknesses from 15 to 30 μm were easily prepared by changing emulsion composition and curing conditions. Micrographs of SEM showed that the hollow microspheres had smooth surface and good sphericity. These boron carbide ceramic hollow microspheres are of significant importance for application in the field of neutron moderator in nuclear reactors, power generation in deep space flight, etc.

Abstract: Ceramic cordierite-based materials are widely used in metallurgy, mechanical engineering and in the chemical industry as refractories, filters and catalyst supports. In this article, the activation of the synthesis of cordierite ceramics additives obtained by SHS is described. These additives consist of a mixture of mineral and alumina nanopowder in various ratios.

Abstract: Two kinds of iron-containing ceramic precursors, PFS and PS-b-PFS, were synthesized via living anionic polymerization by using ferrocenyldimethylsilane and styrene as the monomers. The structures, elemental compositions and molecular weights were characterized by FT-IR, NMR, EDS and GPC, respectively. The homopolymerization of ferrocenyldimethylsilane was simulated using computational chemistry method. The copolymerization between ferrocenyldimethylsilane and styrene was investigated by altering the ratio between monomers and initiator (n-butyllithium). The experimental results indicated that the M_n, M_w and PDi of homopolymer PFS were 6.91×10³ g/mol, 8.29×10³ g/mol and 1.20, respectively. Moreover, the molecular weight, structure and composition of block copolymers PS-b-PFS, were successfully controlled by changing the ratio of styrene, n-butyllithium and ferrocenyldimethylsilane. Subsequently, using such iron-containing polymers as precursors, Fe/Si/C ceramics were obtained after sintering at 1400°C. The microstructures, morphologies and elemental compositions of ceramics were characterized by SEM and EDS. The results implied the controllable preparation of spherical Fe/Si/C ceramics was achieved via the self-assembly of precursors.

Abstract: Iron-containing SiC ceramics have low specific resistivity and excellent electromagnetic properties. In this work, hyperbranched polyferrocenylsilane as the precursor of Fe/Si/C ceramics was prepared by the reaction of ferrocenyl dilithium, dichlorodimethylsilane and trichloromethylsilane. The ceramization process of the preceramic polymer from organic to inorganic was then investigated. Precursor microspheres were prepared by emulsion method, which were then pyrolyzed to obtain Fe/Si/C ceramic microspheres.The composition, structure and morphologies of the precursor and ceramics were characterized by ¹H-NMR, FT-IR, TG-MS, XRD, SEM and EDS. Experimental results showed that the hyperbranched precursor was successfully synthesized, the pyrolytic process of which started at 350 °Cand almost completed above 600 °C. There was crystalline transformation from Fe₅Si₃ to Fe₃Si as the sintering temperature increased from 1000 °C to 1400 °C. Moreover, the crystalline phase of β-SiC appeared at 1400 °C. Precursor microspheres were prepared by emulsion method. Porous ceramic microspheres were obtained after the precursor microspheres being sintered at 1400 °C, which can be applied in gas adsorption and catalyst supports.

Abstract: The lithium ion-sieve precursor was prepared with LiOH and Mn (CH₃COO)₂ as the starting reagents, H₂O₂ as the oxidant and ethanol solution (volume percent 2.5%) as solution by combination of sol-gel, hydrothermal and low-temperature solid state methods, and then changed into lithium ion-sieve after eluting Li⁺ by the mixture of HCl and Na₂S₂O₈ solution. The influence of synthetic conditions on the structures and adsorption properties of lithium ion-sieve was investigated in detail. The results suggest that the pure phase lithium ion-sieve can be synthesized when Li/Mn molar ratio is 3/1, 3.2mL H₂O₂ is added after LiOH and Mn (CH₃COO)₂ react for 36h and the heat treatment way of programmed temperature from 410°C (2h) to 510°C (3h) is adopted in the progress of solid state reaction. The loss rate of dissolved Mn is less than 2.5% during pickling Li⁺. And the highest adsorption capacity can achieve 20.5mg/g.