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Master's Dissertation
DOI
https://doi.org/10.11606/D.85.2020.tde-12032020-075042
Document
Author
Full name
Janine Neméh
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2019
Supervisor
Committee
Lazar, Dolores Ribeiro Ricci (President)
Colen, Inês dos Santos Flores Barbosa
Matai, Patricia Helena Lara dos Santos
Title in Portuguese
Avaliação da influência da aplicação de compósitos de titânia e sílica na preservação de pedras ornamentais
Keywords in Portuguese
absorção de água
compósito
pedras ornamentais
preservação de patrimônio histórico
sílica
titânia
Abstract in Portuguese
A conservação de pedras de patrimônios históricos tem sido foco de diversas pesquisas, principalmente na Europa. Um dos procedimentos estudados é a aplicação de suspensões de sílica com adição de titânia em superfícies de pedras. Essa camada protetora tem sido considerada eficaz, pela estabilidade térmica sob a radiação solar, caráter hidrofóbico da sílica sintetizada e fotocatalítico da titânia. No presente estudo foram avaliadas amostras frescas de pedras ornamentais (granitos e mármores) antes e após a aplicação do compósito sílica-titânia, preparado pela adição de 1 a 2% (p/v) de titânia (Aeroxide ®TiO2 P25) em tetraetilortosilicato (TEOS) na presença de n-octilamina. A aplicação do compósito nas pedras foi feita com pincel, e a secagem das pedras ocorreu ao ar. As técnicas empregadas para caracterização dos pós de partida, compósitos e pedras foram: difração de raios X, microscopia eletrônica de varredura, porosimetria a hélio, medidas de ângulo de contato, espectrofotometria e brilho. Com base em análises de ângulo de contato, espectrofotometria e microscopia eletrônica de varredura, verificou-se a viabilidade de aplicação do compósito com 1% (p/v) de titânia nas pedras com acabamento tipo levigado. As variações colorimétricas foram resultantes do percentual de titânia no compósito e, de modo geral, esse percentual foi determinante também nas variações de ângulos de contato, cujos valores aumentam com a deposição de compósito. Definida a aplicação com 1% (p/v) de titânia nas superfícies das pedras, foram incluídos os testes de absorção de água - método da esponja, de capilaridade e tubo de Karsten. Verificou-se que as pedras tratadas apresentam menor tendência de absorção de água, em tempos menores de ensaios, notadamente, as silicáticas.
Title in English
Evaluation of the influence of titania and silica composites application on the preservation of ornamental stones
Keywords in English
composite
ornamental stones
preservation of historical heritage
silica
titania
water absorption
Abstract in English
The conservation of historic heritage stones has been the focus of several researches, mainly in Europe. One of the procedures studied is the application of silica suspensions with the addition of titania on stone surfaces. This protective layer has been considered effective by the thermal stability under solar radiation, hydrophobic character of the synthesized silica and photocatalytic behavior of titania. In the present study, fresh samples of ornamental stones (granites and marbles) were evaluated before and after the application of the silica-titania composite prepared by adding 1 to 2% (w / v) titania (Aeroxide ®TiO2 P25) in tetraethylorthosilicate (TEOS) in the presence of n-octylamine. The application of the composite on the stones was performed with a brush, and the drying of the stones occurred in the air. The techniques used to characterize the starting powders, composites and stones were: X-ray diffraction, scanning electron microscopy, helium porosimetry, contact angle measurements, spectrophotometry and shine. Based on analysis of contact angle, spectrophotometry and scanning electron microscopy, it was verified the feasibility of applying the composite with 1% (w / v) titania on the stones with a levigated type finish. The colorimetric variations were the result of the percentage of titania in the composite, and in general, this percentage was also determinant in the variations of contact angles, which increase with composite deposition. The water absorption tests - sponge method, capillary method and Karsten's tube were included in the application of 1% (w / v) titania to the stone surfaces. It was verified that the treated stones have a lower tendency of water absorption, in smaller times of tests, notably the silicatic stones.
 
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Publishing Date
2020-03-12
 
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