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Using a chelation-precipitation method, five samples were synthesized in the presence of chelating agents by altering the proportion of ZnO to Mn3O4. Specifically, Z contains only ZnO, Z3M1 has a 3:1 ratio of ZnO to Mn3O4, ZM has equal parts of both oxides, Z1M3 consists of one part of ZnO to three parts of Mn3O4, and M is pure Mn3O4. The synthesized powders were calcined at 600 °C and 1000 °C. The prepared and calcined powders were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The magnetic and antimicrobial properties of the calcined powders were also investigated. The XRD results showed that powder Z was in the wurtzite phase, and M was Mn3O4 with a pure tetragonal phase after calcination at 1000 °C. ZM was a pure ZnMn2O4 spinel. Z3M1 is formed from spinel and ZnO, and Z1M3 is formed from spinel and Mn3O4. The magnetic nature of the powders varies from diamagnetic to ferromagnetic to paramagnetic. Powders with a higher ZnO ratio exhibited enhanced antibacterial effectiveness against E. coli. The addition of Mn improved the antibacterial efficacy of most powder against C. albicans. Pure ZnO has high antibacterial efficiency against M. lutus. These results demonstrate how the components of these powders affect their crystalline structure, magnetic properties, and antimicrobial efficacy against various microorganisms. These findings may have significant implications for the development of advanced antimicrobial agents with tailored properties for use in medical devices, water treatment systems, or food packaging materials. [ABSTRACT FROM AUTHOR]

This work represents the shaping of alumina–zinc oxide (AZ) samples with the direct coagulation casting method. The effect of zinc oxide (0, 10, 20, 30, and 40 wt%) and the firing temperatures on the phase composition, microstructure, physical properties, and mechanical properties of the AZ samples were studied. The effect of titanium oxide (2, 5, and 7 wt%) and the firing temperatures on the phase composition, microstructure, physical properties, and mechanical properties of the AZ sample with 40 wt% of zinc oxide were studied. Furthermore, the optical properties, magnetic properties, and antimicrobial activity were measured. The results indicate that the increase in zinc oxide enhances the formation of zinc aluminate, which has a gahnite phase. Moreover, increasing the zinc oxide increases the apparent porosity and decreases the grain size and bulk density at various firing temperatures. On the other hand, the addition of 5 wt% titanium oxide increases the bulk density to 3.5 g/cm3 compared to 1.72 g/cm3 with no titania. The apparent porosity and compressive strength reached 5% and 69.2 MPa after 5 wt% TiO2 addition; respectively, compared to 59% and 27.2 MPa with no titania addition. The prepared samples show promising optical band gap of 2.98–3.97 eV, a mixed magnetic behavior, and favorable antibacterial activity against E. coli, S. aureus, B. cereus strains. [ABSTRACT FROM AUTHOR]

The study focuses on synthesizing wollastonite using bypass and silica fume waste materials as starting materials. The novelty of this work is the utilization of temperature-induced forming technique for the synthesis of wollastonite. Bypass and silica fume are mixed with various CaO/SiO2 ratios and then cast and fired at temperatures ranging from 900 to 1200 °C. Rheological properties and zeta potential are characterized for the slurries to optimize the dispersant percentage. The fired samples' phase composition, structure properties, apparent porosity, linear shrinkage, and compressive strength are characterized. Results show that the sample with a CaO: SiO2 ratio of 1:1.45 is the optimum composition for forming mainly pure β-wollastonite at 1100 °C, which changed into pseudo-wollastonite at about 1150 °C. The best physical and mechanical properties are obtained at 1170 °C, including apparent porosity of 8%, bulk density of 2.2 g/cm3, linear shrinkage of 13%, and compressive strength of 40 MPa, which widens its ceramic applications. [ABSTRACT FROM AUTHOR]

The study describes the successful development of a TiO2 ceramic substrate with a protective nano-Al2O3 coating using two different coating techniques: microwave combustion and polymeric methods. The coated ceramics demonstrate enhanced corrosion resistance compared to the uncoated substrate. The optimal TiO2 substrate was prepared by firing it at 1000 °C. This was done to give the desired physical properties of the TiO2 substrate for the coating procedures. Nano-Al2O3 powder was coated onto the surface of the TiO2 substrates. The TiO2 substrates with the Al2O3 coating were then calcined (heat-treated) at 800 and 1000 °C. The structures, morphology, phase composition, apparent porosity, bulk density, and compressive strength of the substrate and coated substrate were characterized. Upon firing at 1000 °C, it was discovered that the two phases of TiO2—rutile and anatase—combine in the substrate. Once the substrate has been coated with nano Al2O3 at 1000 °C, the anatase is transferred into rutile. When compared to the substrate, the coated substrate resulted in a decrease in porosity and an increase in strength. The efficiency of the ceramic metal nanoparticles Al2O3 as a good coating material to protect the TiO2 substrates against the effect of the corrosive medium 0.5 M solution of H2SO4 was measured by two methods: potentio-dynamic polarization (PDP) and the electrochemical impedance spectroscopy (EIS). The results indicated that the corrosion rate was decreased after the substrate coated with alumina from (67.71 to 16.30 C.R. mm/year) and the percentage of the inhibition efficiency recorded a high value reaching (78.56%). The surface morphology and composition after electrochemical measurements are investigated using SEM and EDX analysis. After conducting the corrosion tests and all the characterization, the results indicated that the coated TiO2 substrate prepared by the polymeric method at 800 °C displayed the best physical, mechanical, and corrosion-resistant behavior. [ABSTRACT FROM AUTHOR]

The main goal of this work is to study the effects of some transition metal-oxides, i.e. ZnO, TiO2, and Fe2O3, on inhibition of spinel formation during cordierite fabrication from granite waste, talc, and alumina by direct coagulation casting method. Moreover, the effect of these oxides on sinterability, microstructure, hardness and electrical properties was achieved. The casted specimens were sintered at different temperatures then examined by X-ray diffraction technique to follow the formed phases. The physical properties were determined according to Archimedes rule. The microstructure was also investigated by scanning electron microscope, while the hardness was determined by Vicker's method. The electrical properties were evaluated by an impedance analyzer. The results indicated that sintered cordierite-spinel ceramics were successfully prepared with inhibition of spinel formation after addition of some transition metals and sintering up to 1250 °C. ZnO promoted the formation of spinel while TiO2 and Fe2O3 inhibited the formation of spinel and promoted the formation of cordierite. The ZnO-containing cordierites exhibited their best properties after sintering at 1200 °C, while the samples containing TiO2 and Fe2O3 showed their best properties after sintering at 1250 °C. The physical, mechanical and electrical properties were improved after increasing the amount of added metal oxides. The dielectric constant values were higher for the samples that contain TiO2 than those contain Fe2O3 and ZnO. Moreover, the hardness of all samples was in a narrow range of 6.14–6.61 GPa. [ABSTRACT FROM AUTHOR]