Utilization of industrial waste materials for the preparation of wollastonite by temperature-induced forming technique.

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 ß-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.

Study of microstructure and corrosion behavior of nano-Al2O3 coating layers on TiO2 substrate via polymeric method and microwave combustion.

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.

Effect of nanospinel additions on the sintering of magnesia-zirconia ceramic composites.

Nanocrystalline magnesium aluminate (MA) spinel powder produced through a coprecipitation method and calcined at 900°C for 1 h was added to magnesia-zirconia composite in the range of 0-25 mass % and sintered at 1600°C for 2 h. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used for studying the microstructure and the phase composition of the sintered composites. Bulk density, apparent porosity, volume shrinkage, and Young's modulus of the sintered composites were also investigated. The results revealed that the nanospinel addition up to 20 mass % increases the sintering ability and Young's modulus of the composite bodies. Microstructure showed that the presence of nanospinel and zirconia in the triple point between magnesia grains closed the gaps in the ceramic matrix and enhanced the compactness of the composites.

Nano Mg(1-x)Ni(x)Al2O4 spinel pigments for advanced applications.

Nano Mg(1-x)Ni(x)Al2O4 spinel pigments were synthesized via polymeric combustion technique upon heat treatment at 210 °C. Citric acid in the presence of ethylene glycol polymer, with mass ratio of 60:40, was successfully used as a host network for the synthesis process. The obtained spinel was calcined at different temperatures; 300-1200°C and investigated by thermal analysis (TG-DTG/DTA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). UV-Vis and diffuse reflectance spectroscopy (DRS) using CIE-Lab/parameters methods have been used for color measurements. The addition of colored pigment on different types of glazes was studied. The results revealed that NiMgAl2O4 spinel beside MgNiO phases were crystallized with particle sizes of 9-21 nm at 600 °C and 52-180 nm at 1200 °C. All prepared samples exhibited green to pale green colors due to the inclusion of Ni(2+) inside the spinel structure. The pale green color intensity increased with increasing calcination temperature. The prepared pigment was suitable to convert commercial and opaque glazes to color product to be used in different applications.

Effect of surfactant types and their concentration on the structural characteristics of nanoclay.

A series of organo-modified nanoclays was synthesized using three different surfactants having different alkyl chain lengths and concentrations [0.5-5.0 cation exchange capacity (CEC)]. These surfactants were Ethanolamine (EA), Cetyltrimethylammoniumbromide (CTAB) and Tetraoctadecylammoniumbromide (TO). The obtained modified nanoclays were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) and compared with unmodified nanoclay. The results of XRD analysis indicated that the basal d-spacing has increased with increasing alkyl chain length and surfactant concentration. From the obtained microstructures of these organo-modified nanoclays, the mechanism of surfactant adsorption was proposed. At relatively low loading of surfactant, most of surfactant entered the spacing by an ion-exchange mechanism and is adsorbed onto the interlayer cation sites. When the concentration of the surfactant exceeds the CEC of clay, the surfactant molecules then adhere to the surface adsorbed surfactant. Some surfactants entered the interlayers, whereas the others were attached to the clay surface. When the concentration of surfactant increased further beyond 2.0 CEC, the surfactants might occupy the inter-particle space within the house-of-cards aggregate structure.

Reproductive efficiency of Egyptian buffaloes in relation to oestrous detection systems.

A total of 57 buffalo cows were divided into two groups and subjected to different intensities of oestrous detection. In the first group (G1), oestrus was checked at 6-h intervals, four times daily starting at 0600 h as compared to twice daily in the second group (G2) at 0800 h and 1500 h. The year was also divided into two seasons: cool from November to April; and hot from May to October. Ovulatory activity was monitored by measuring progesterone concentrations in blood serum. Samples were obtained every 3 or 4 days post-partum until conception was confirmed. More frequent detection practices produced shorter intervals for all of the reproductive parameters. Calving interval was less for cows in G1 in the cool season (363.5 +/- 16.0 vs. 400.3 +/- 14.3 days) than in the host season (387.0 +/- 15.3 vs. 441.5 +/- 14.3 days). Oestrous detection efficiency was higher (P < 0.01) in G1 in both seasons. Season of calving produced a significant effect (P < 0.05) on the number of services per conception. The cool season calvers had better reproductive performance than cows calved during the hot season.