SYNTHESIS OF HYDROPHOBIC COATING USING A SOL-GEL PYROLYTIC SPRAY COATING SYSTEM

摘要

This paper reports the synthesis of hydrophobic coatings using sol-gels approach of a mixture of two sorts of chemicals: tetraethylorthosilicate (TEOS) as a glass binder precursor and heptadecafluorodecyltrimethoxysilane (HFTMS) as a surface modifying agent deposited using the low-temperature pyrolytic spray coating process. The target glass substrate was priorly coated with TEOS for the surface preparation of TEOS:HFTMS coating at ethanol evaporation temperature of 60 degrees C. The hydrophobic TEOS:HFTMS sol-gel was prepared at fixed weight ratio of 10:1 without using any acidic/alkaline catalyst to ensure uniform sol-gel's particle size and to eliminate the clogging problem at the nozzle during the spray process. The coated sample had shown high hydrophobic properties with maximum water contact angle of 109 degrees at low grain height and surface roughness. From atomic force microscopy (AFM) surface topology measurement, it was found that the pyrolytic spray coating technique is capable of tuning the surface properties and grain dimension simply by changing the atomizing air pressure, number of paths and chemical flowrate. This was due to the unique approach by spraying the coating at evaporation temperature of the coating solvent. The technique can be utilized to surface engineering the final quality of a thin film coating.