Organosilane coatings applied on bronze: Influence of UV radiation and thermal cycles on the protectiveness

Abstract

a b s t r a c t3-Mercapto-propyl-trimethoxy-silane (PropS-SH) coatings, with or without the addition of three types of oxide particles (CeO 2 (nano-sized), TiO 2 (nano-sized) and La 2 O 3 (micro-sized)), were applied on quaternary bronze (Cu-Sn-Zn-Pb) and tested through natural and artificial exposures. In particular, uncoated and coated samples were exposed both in the coastal town of Rimini (Italy) under sheltered/unsheltered conditions and in a climatic chamber where the samples underwent temperature/UV cycles, at constant humidity. The sample surfaces were periodically characterized by SEM, EDS, micro-Raman, FTIR and XRD techniques. Moreover, during natural exposures, runoff rainwater was collected monthly, in order to evaluate the release of the alloying metals from bronze by atomic absorption spectrometry (AAS). The results showed that micro-scale cracking and spalling phenomena took place during natural exposure, partly limiting the protective efficiency of the organosilane coating. In fact, UV radiation has a strong influence on coating performance, inducing structural modifications of the polymer. Oxide particle-and especially TiO 2 -charged coatings proved to be more resistant to UV degradation.

Comparative anti-corrosion properties of alkylthiols SAMs and mercapto functional silica sol–gel coatings on copper surface in sodium chloride solution

“…A great many works have been carried out on the formation of alkylthiols SAMs and mercapto functional silica sol-gel coatings on copper surface [7][8][9][10][11][12][13][14][15]. The impact of concentration, additives and pH value of the coating solution on the protective effect has been studied extensively as well [16][17][18][19][20]. However, few studies concentrated on the corrosion resistance comparison between alkylthiol SAMs and mercapto functional silica sol-gel coating in sodium chloride solution.…”

Atmospheric corrosion of fire-gilded bronze: corrosion and corrosion protection during accelerated ageing tests

“…However, outstanding results were obtained with silanes containing sulphur or mercapto groups, such as bis-[triethoxy-silylpropyl]tetrasulfide [24], 3-mercapto-propyl-triethoxy-silane [25]or 3-mercapto-propyl-trimethoxysilane (PropS-SH) [26][27][28][29][30][31][32][33][34].…”

Inclusion of 5-Mercapto-1-Phenyl-Tetrazole into β-Cyclodextrin for Entrapment in Silane Coatings: An Improvement in Bronze Corrosion Protection

“…No significant E cor differences were detected in the presence of the coatings. In all cases, E cor increased to a certain extent during the initial 2 or 3 days of immersion, likely due to the evolution in the coating reticulation [39]. Then, they reached values in the range from 0.011 to 0.030 V SCE , independently of the corresponding R p values.…”

“…Silane hydrolysis was carried out by dissolving PropS-SH in a hydroalcoholic solution (90/5/5 v/v ethanol/water/PropS-SH), acidified to pH 4 by the addition of some drops of diluted sulphuric acid solution, according to the methodology refined in previous research works [29,[38][39][40].…”