Study of the Sol-gel thin-film ammonia curing process

Study of the Sol-gel thin-film ammonia curing process

Christophe Boscher  Jérémy Avice  Philippe Belleville  Herve Piombini  Karine Vallé 

CEA, DAM Le Ripault, 37260 Monts, France

Corresponding Author Email:
31 December 2017
| Citation



The adhesion of sol-gel antireflective coatings on optical components is improved by an exposition into ammonia vapors. Coatings of 70 or 210 nm thickness are deposited by dip-coating and consisted in a collection of nanoparticles having an average diameter of 10 nm. The micro- porosity is about 55% and by the way the refractive index can be as low as 1.22. The synthesis results of the hydrolyze-condensation in a basic environment of tetraethyl orthosilicate in an alcoholic  solution. Like coatings  have  a   low  adhesion,  they’re consequently easily damaged mechanically. To increase the cohesion of these colloidal thin films, a chemical modification of the nanoparticles is achieved thanks to a post-processing using  ammonia   vapors,   called  ”ammonia   curing   process”.  This  process  induces a modification of the noncontact chemical bonds from Van der Walls to Hydrogen & Covalent bonds. The increase in strength of the films is accompanied by 20% shrinkage in thickness but without changing the antireflective properties. This change in thickness is also accompanied by a modification of the chemistry of the nanoparticles. The purpose of this study is to follow these two main coating changes resulting from the post treatment in order to optimize it for an industrial process


sol-gel, antireflective, silica, ammonia, curing

1. Introduction
2. Revêtement antireflet à base de silice colloïdale
3. Évolution de l’épaisseur en fonction de la durée du durcissement
4. Évolution de la chimie de surface en fonction de la durée du durcissement
5. Conclusion

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