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

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