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Formation of Hydrophobic Silica Coatings on Stones for Conservation of Historic Sculptures
Author(s) -
Xu Feigao,
Li Dan,
Chen Weiling,
Gao Shixiang
Publication year - 2010
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201090254
Subject(s) - chemistry , contact angle , coating , molar ratio , nanocomposite , chemical engineering , weathering , nuclear chemistry , catalysis , organic chemistry , geomorphology , engineering , geology
The conservation of historic sculptures is receiving growing attention because of the increasing air pollution. A hydrophobic silica coating was synthesized to protect historic sculptures from weathering by starting from a solution of tetraethoxyorthosilicate (TEOS) precursor using hexadecyltrimethoxysilane (HDTMS) as hydrophobic modifier in the presence of ammonia as a catalyst. The molar ratio of ethanol, TEOS, H 2 O and NH 4 OH was kept constant at 8:0.045:3:2.8 and the molar ratio of HDTMS/TEOS ( M ) was varied from 0 to 0.458. The organic modification was confirmed by infrared spectroscopic studies, and the hydrophobicity of the coating was tested by the contact angle measurements. The stone surface morphology of sample treated with silica coating was characterized. The results showed that the nanocomposites were composed of spherical particles with grain size of about 190 nm in diameter. After the limestone's surface was modified, the contact angle of limestone increased from 20° to 100° for M 0.458. The protective performance evaluated with its ability to resist acid rain reveals that the protective effects are satisfying.