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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/SiO 2 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: SiO 2 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/cm 3 , linear shrinkage of 13%, and compressive strength of 40 MPa, which widens its ceramic applications., (© 2024. The Author(s).)

The study describes the successful development of a TiO 2 ceramic substrate with a protective nano-Al 2 O 3 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 TiO 2 substrate was prepared by firing it at 1000 °C. This was done to give the desired physical properties of the TiO 2 substrate for the coating procedures. Nano-Al 2 O 3 powder was coated onto the surface of the TiO 2 substrates. The TiO 2 substrates with the Al 2 O 3 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 TiO 2 -rutile and anatase-combine in the substrate. Once the substrate has been coated with nano Al 2 O 3 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 Al 2 O 3 as a good coating material to protect the TiO 2 substrates against the effect of the corrosive medium 0.5 M solution of H 2 SO 4 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 TiO 2 substrate prepared by the polymeric method at 800 °C displayed the best physical, mechanical, and corrosion-resistant behavior., (© 2024. The Author(s).)