Table of Contents
What are the components used in the sol-gel method?
Sol–Gel Process and Applications For this purpose, sol–gel preparation of simple and complex nonsilica oxides, including TiO2, ZrO2, Al2O3, ZnO, WO3, Nb2O5, rare earth oxides, and so on, have to be studied. Metal alkoxides are often employed for those oxides.
What is sol-gel theory?
This theory was strongly advocated by Hyman (1917) and also adopted by Pantin and Mast . It is supposed to be the best to explain the locomotion in Amoeba. This theory is based on the reversible change of protoplasm from sol to gel state.
Which process is involved in the transformation of sol to gel?
(i) Synthesis of the ‘sol’ from hydrolysis and partial condensation of alkoxides. (ii) Formation of the gel via polycondensation to form metal–oxo–metal or metal–hydroxy–metal bonds. (iii) Syneresis or ‘aging’ where condensation continues within the gel network, often shrinking it and resulting in expulsion of solvent.
What are the precursors used in sol-gel technique?
Typical precursors are metal alkoxides and metal chlorides, which undergo hydrolysis and polycondensation reactions to form a colloid. The basic structure or morphology of the solid phase can range anywhere from discrete colloidal particles to continuous chain-like polymer networks.
What are the advantages of sol gel coatings over other ceramic coatings?
In comparison to organic polymer coatings, inorganic sol–gel coatings have some advantages such as high mechanical, chemical, and thermal stability, biological inertness, high transparency and photostability, controllable porosity, and release of embedded agents.
What are the importance factor that influence the film thickness in spin coating?
The two main factors that define film thickness are the spin speed and the viscosity of the solution. Other factors considered include spin time, solution density, solvent evaporation rate, and surface wettability.