Advantages And Disadvantages Of Film Coatings

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Banerjee et al. [18] observed that the sprayed liquid droplet tends to flatten out into a disk on impact with substrate surface and the geometry of the disk depends mainly on the momentum and volume of the droplet and also on the substrate temperature.
The thin film formation is a resultant of the following processes:
i) spreading of the sprayed droplets on the surface of the hot substrate into disks ii) pyrolytic reaction between the decomposed reactants iii) evaporation of the solvent iv) repetition of the proceeding processes with succeeding droplets.
The process parameters such as concentration of the precursor solution, type of solvent, doping material, spray nozzle geometry, flow rate of carrier gas and solution, velocities of sprayed droplets, nature and temperature of the substrate, kinetics and thermodynamics of the pyrolytic reaction mainly determine the properties of the spray deposited films.
3.4.2. Advantages of spray pyrolysis technique over other techniques Spray pyrolysis is one of the simple and cost effective techniques suitable for commercial and mass production of thin film coatings [19]. It is a fast coating process easily applicable for large area depositions at atmospheric conditions. In addition to the inexpensive and simple experimental arrangement, this method has several
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These include precursor solution atomization, droplet transport and evaporation, spreading on the substrate, drying and decomposition of the precursor salt. Understanding these processes will help to improve film quality. Thin film deposition using spray pyrolysis can be divided into three main steps: atomization of the precursor solution, transportation of the resultant aerosol and decomposition of the precursor on the substrate.
a) Atomization of precursor
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