Effects of pre-strain applied at a polyethylene terephthalate substrate before the coating of Al-doped ZnO film on film quality and optical and electrical properties

Five kinds of polyethylene-terephthalate (PET)/aluminum-doped zinc oxide (AZO) specimen were prepared to examine the effect of strain applied to the PET substrate before the coating of AZO film on the mechanical, optical, and electrical properties and morphology. An increase in the strain of PET increases the reflection intensity, resulting in a significant reduction in absorption. The largest mean surface roughness was obtained for the PET-4%/AZO specimen. XRD diffraction peaks of ZnO (002) indicate that the quality of the AZO film initially improved with increasing strain, and then degraded with further increases. Compressive residual stresses formed in the bending specimens at various strains; the residual stress increased with decreasing 2θ angle. A higher compressive stress in the AZO film resulted in a lower optical band gap and a lower transmittance; it also led to an increase in the sheet resistance of the AZO film, and thus a lower carrier mobility.     

Biomorphic silicon/silicon carbide ceramics from birch powder

A novel process has been developed for the fabrication of biomorphic silicon/silicon carbide (Si/SiC) ceramics from birch powder. Fine birch powder was hot-pressed to obtain pre-templates, which were subsequently carbonized to acquire carbon templates, and these were then converted into biomorphic Si/SiC ceramics by liquid silicon infiltration at 1550 °C. The prepared ceramics are characterized by homogeneous microstructure, high density, and superior mechanical properties compared to biomorphic Si/SiC ceramics from birch blocks. Their maximum density has been measured as 3.01 g/cm³. The microstructure is similar to that of conventional reaction-bonded silicon carbide. The Vicker's hardness, flexural strength, elastic modulus, and fracture toughness of the biomorphic Si/SiC were 19.6 ± 2.2 GPa, 388 ± 36 MPa, 364 ± 22 GPa, and 3.5 ± 0.3 MPa m^1/2, respectively. The outstanding mechanical properties of the biomorphic Si/SiC ceramics are assessed to derive from the improved uniform microstructure of the pre-templates made from birch powder.     

Synthesis and characterization of hollow glass–ceramics microspheres

Hollow glass–ceramics microspheres (HGCM), with the diameter from 10 μm to 60 μm and the shell thickness less than 2 μm, were successfully fabricated by a simple technique using polyacrylamide microspheres (PAM) as template. The corresponding HGCM were obtained by a thermal treatment of the core–shell microspheres, which were synthesized with organic template method. The size, morphology and phase composition of synthesized products were determined via XRD, SEM, TGA. The effects of the amount of glass powder, the Hydrophile–Lipophile Balance (HLB) value, the sintering temperature, and the ratios of pre-adsorbed water and the water in the slurry on the morphologies of HGCM have been investigated. The results showed that the agglomeration of HGCM can be reduced by adjusting the HLB value. In addition, the amount of solid beads decreases obviously by reducing ratios and adjusting the HLB value. As the sintering temperature increases, the surface of the HGCM becomes smooth and compact.     

Hydrothermal and post-heat treatments of TiO2/ZnO composite powder and its photodegradation behavior on methyl orange

The composite powder of TiO₂/ZnO with an atomic ratio of Ti to Zn of 3/1 was prepared through sol–gel process followed by hydrothermal and post-heat treatments. The as-prepared powder was characterized in detail by means of XRD, TG/DTA, DLS, and SEM. The XRD results showed that by applying the hydrothermal process the crystallinity of the composite powder was significantly improved. The SEM and DLS results revealed no visible variations on particle morphology and size owing to the hydrothermal and post-heat treatments. The enhancement of the photocatalytic activity of the composite powder evaluated through methyl orange (MO) degradation under UV light irradiation was, therefore, attributed to its high crystallinity that was achieved during the hydrothermal process under a rather low temperature.     

Structural and luminescence properties of RE (RE = Eu, Tb):(MgCa)2Bi4Ti5O20 ceramics

Rare-earth ions (Eu³⁺, Tb³⁺) activated magnesium calcium bismuth titanate [(MgCa)₂Bi₄Ti₅O₂₀] ceramics were prepared by conventional solid state reaction method for their structural and luminescence properties. By using XRD patterns, the structural properties of ceramic powders have been analyzed. Emission spectrum of Eu³⁺:(MgCa)₂Bi₄Ti₅O₂₀ ceramic powder has shown strong red emission at 615 nm (⁵D₀ → ⁷F₂) with an excitation wavelength λ_exci = 393 nm and Tb³⁺:(MgCa)₂Bi₄Ti₅O₂₀ ceramic powder has shown green emission at 542 nm (⁵D₄ → ⁷F₅) with an excitation wavelength λ_exci = 376 nm. In addition, from the measurements of scanning electron microscopy (SEM), Fourier transform-infrared (FTIR) and energy dispersive X-ray analysis (EDAX) results the morphology, structure and elemental analysis of these powder ceramics have been studied.     

Regeneration of a solid waste from an edible oil refinery

This work presents a valorization of a solid waste originating from an edible oil refinery called spent bleaching earth (SBE). The SBE material is first impregnated with an ammonium chloride solution (3 M), then treated directly in furnace at 400 °C during an hour followed by a washing in the cold by HCl 1 M. To elucidate the changes in its crystalline structure, induced by the regeneration method, the obtained material (RSBE) is characterized by several physicochemical methods (X-ray diffraction, FTIR, thermal analysis, BET and SEM). The characterization results show that the heat treatment in furnace and the chemical treatment (decomposition of NH₄Cl) don’t affect the structure of montmorillonite of regenerated material (RSBE). The study of porous texture by the nitrogen adsorption technique at −196 °C shows that the specific surface area S_BET and the pore volume increased in the RSBE material compared to those of virgin bleaching earth VBE (unused) and their values are respectively of 145.68 against 115.5 m² g⁻¹ and of 0.287 against 0.234 cm³ g⁻¹. Calculations by the adsorption equations using BJH method, applied to both materials, show that the treatment generate an increase in the micropores in the RSBE material. We belonged the values of the micropores area of S_mic = 41.98 cm² g⁻¹ and of V_mic = 0.074 cm³ g⁻¹ for the volume.     

Effect of bentonite addition on fabrication of reticulated porous SiC ceramics for liquid metal infiltration

SiC with different particles and a clay mineral bentonite (montmorillonite) were mixed in water to prepare ceramic slurry. The slurry was then infiltrated high porous polyurethane sponge. Excess slurry was squeezed out to adjust ceramic rate in the infiltrated body. The pore walls were coated with ceramic mix after the infiltrated body was dried. The polyurethane containing SiC particles and bentonite was fired in a box furnace to burn out the polyurethane from the body at 500 °C for 30 min. The remaining porous ceramic bodies were sintered at elevated temperatures to give strength. SiC particles with bentonite surface coating took polyurethane pore forms after firing the sponge. Bentonite was both used as binder for ceramic slurry at room temperatures and the sintering additives at elevated temperatures. Therefore, increasing bentonite addition gives higher strength to the resulting ceramic performs.     

Pore-forming agent induced microstructure evolution of freeze casted hydroxyapatite

There were interconnected small lamellar pores, big spherical pores and ceramic walls in the hydroxyapatite (HAP) ceramics fabricated by a freeze casting/pore-former method. As keeping the content of polymethyl methacrylate (PMMA) constant and decreasing the size of PMMA, the size of spherical pores and length of ceramic wall both decreased, and the compressive strength increased. As keeping the size of PMMA and decreasing the content of PMMA, the open porosity decreased and compressive strength increased. The shapes of pores caused by ice crystals were reticular, lamellar and treelike, in turn. The HAP ceramics with the spherical pores of 150-250 μm, open porosity of 62.13% and compressive strength of 7.01 MPa are prospective to have biomedical application.     

B族维生素对B-Z振荡的扰动及其测定

研究了维生素B1、B2和B6对以丙二酸-硫酸铈铵-溴酸钾-硫酸振荡体系的扰动,得出不同浓度的维生素B1、B2和B6能够对该振荡反应曲线的△E(振幅即振荡强度)和△t(振荡周期)产生明显影响;组成浓度、反应温度和自由基对该振荡反应也有影响;得出不同B族维生素的浓度与振荡周期变化值及振幅变化值均有良好的线性关系;得出检测维...     

The effect of reactor temperature gradient on microstructures of sodium borosilicate glass powders produced by ultrasonic spray pyrolysis technique

Sodium borosilicate glass powders were produced by ultrasonic spray pyrolysis technique for three different reactor temperature gradients and the effect of the reactor temperature gradient on the microstructures of the powders produced was investigated. A three-zone ultrasonic spray pyrolysis system reactor in which the temperatures of each zone could be controlled separately was designed for this purpose. When the drying speed is high, early shell formation was observed in the aerosol droplets due to the difference of the drying speed between inner and outer parts and hollow powders were produced. In order to produce dense powder particles, shell formation on the aerosol droplet should be prevented, therefore drying speed should be decreased. The powders produced were glass-structured, spherical shaped and with smooth surfaces. The density of the hollow powder particle was 1.9 g/cm³ while the density of the dense particle was 2.5 g/cm³.