Sol-gel process for the preparation of porous coatings, using precursor solutions prepared by polymeric reactions

摘要

The process, performed by immersion or spraying techniques, permits preparing vitreous or polycrystalline coatings with variable compositions and high porosity that have excellent homogeneity, adherence and mechanical properties, reducing the losses due to reflection of radiation falling on substrates as varied as glass, metals, ceramic materials and thermal and photovoltaic solar cells. The porosity and, in consequence, the anti-reflective properties, is controlled by an additive that comprises compounds derived from Polyethyleneglycol tert-octyl phenyl ether (Triton) in high concentrations, between 5 and 50 g/l, and subsequent thermal sintering treatment to cause the combustion of the additives. In this manner, the porosity is increased when the amount of additives increases. The process is simple and economical, and is applicable to improving the transmittance of glass and the efficiency of thermal and photovoltaic solar devices.