Leonard Namwiha
A coating of dispersed fine silica particles in ethanol, without any other additives, will likely form a thin, transparent or translucent film after the ethanol evaporates. The appearance and properties of the coating will depend on factors such as the concentration of silica particles, the size and shape of the particles, and the method used to apply the coating.
Here's what you might expect:
1. Transparent Film: If the silica particles are dispersed uniformly in the ethanol and applied evenly onto a substrate, the resulting coating is likely to be transparent, especially if the particles are fine and well-dispersed.
2. Smooth Surface: Assuming the silica particles are well-dispersed in the ethanol and applied onto a flat surface, the coating is likely to have a relatively smooth surface. However, if the particles are not uniformly dispersed or if the coating process introduces agitation or unevenness, the surface may have some roughness.
3. Enhanced Surface Properties: Silica particles can provide various surface properties such as increased scratch resistance, improved adhesion, and enhanced hardness. These properties may be present in the coating depending on the particle size and concentration.
4. Potential for Optical Effects: In some cases, if the coating is thin enough and the silica particles are of the right size and distribution, you might observe optical effects such as interference or diffraction patterns, which could give the coating a slightly iridescent or pearlescent appearance under certain lighting conditions.
5. Uniformity and Clarity: The uniformity and clarity of the coating will depend on the quality of dispersion achieved during the mixing process and the uniformity of application onto the substrate. Poor dispersion or uneven application could result in non-uniform coating thickness and reduced clarity.
Overall, the coating of dispersed fine silica particles in ethanol is likely to form a thin, transparent film with potential enhancements in surface properties, but the specific appearance and properties will depend on several factors including particle size, distribution, concentration, and application method.
How are you dispersing in ethanol? What are you coating with your silica?
I would suggest that although I basically agree with Chavan (the commenter above), the answer is going to be dependent upon these two factors. You have to assure yourself that your dispersion is uniform, the particles don't agglomerate and the ethanol wets the surface that you are trying to coat. Further the affinity (or surface energy) relationships between any exposed surface, the coating and the furnace environment will play a role in how the coating uniformity upon sintering.
Gary Fischman Thanks, Gary, I see. AR coating on a PV glass substrate. There is a dependence on particle size. What dispersion and binder agent do you suggest if I use bigger particles (250 nm) for that?
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