Keywords: corrosion protection, nanosilica, hydrophobic coatings, cultural heritage, antiques, Iran, nanotechnology, protective coatings, nanocomposites, corrosion resistance, ancient artefacts
Synthesis and characterisation of nano silica-based coatings for protection of antique articles
Antique articles are endangered by environmental effects such as humidity, UV and variation of temperature. Improved physical surface resistance is in an increasing demand in protection of cultural heritage. One possible way is their protection by suitable hydrophobic coatings. In this work, the experimentation of protective treatments on the soda glass, mud brick and copper, characteristic materials of Iranian antique articles was performed. The study was carried out using two commercial polymeric resin and three developed hybrid coatings were prepared by sol-gel technique. In particular, siloxane, silicon and fluorinated resin were considered in different chemical compositions as protective coatings. The protectiveness of the treatments was evaluated performing artificial weathering, contact angle measurements as well as corrosion behaviour studies. In order to estimate the effectiveness of the coating treatments, colorimetric measurements were carried out on the 500 h artificial weathering aged samples. Moreover, the hydrophobic properties of the coated surfaces were determined by static contact angle measurements on the treated samples. In addition, the corrosion behaviour of the hybrid nanocomposite coatings were evaluated by charting the Tafel curves of the NaCl solution at room temperature. Results show that the coatings were uniform and transparent. Weathering resistance and hydrophobicity of two commercial coating systems were found well. However, their colorimetric results show more ΔE during exposure. All the hybrid coatings have good resistance to colour changes. Furthermore, corrosion resistance and hydrophobicity of the fluorinated hybrid coatings were found excellent.