SO2气体对不同石材防护涂料的影响

Effects of Atmospheric SO_2 on Carbonate Stone Coated with Different Protective Products

大气中SO2气体是造成石灰质文物化学腐蚀的最重要因素之一。设计了一套SO2老化装置来评价两种有机硅防护涂料(Pelicoat和Mellerud),在浓度30mg/m3SO2下的防护石材效果情况。使用毛细管吸收量评价防护涂料的保护程度,使用接触角评价防护涂料的疏水性,使用离子色谱测定石灰岩腐蚀层中形成的硫酸盐,根据硫酸盐的量决定石灰岩的腐蚀程度。实验结果表明,两种防护涂料老化480h后,其保护系数均有不同程度的减少。随着老化时间的增加,用Pelicoat、Mellerud涂覆的样品接触角逐渐减少,Pelicoat的降幅要大于Mellerud,两种防护涂料抗SO2防护效果下降。SEM电镜发现样品经过老化涂覆后,试样表面孔隙变大、孔隙数增加。

One of the most important factors of carbonate decay is the chemical attack caused by atmospheric pollutants such as SO2. A SO2 ageing system was designed to evaluate the effects of SO2 （30 mg/m^3 ） on two commercial fluoro - organosilane （ Pelicoat and Mellerud） for the protection of carbonate stone. The coating＇s protective efficiency and hydrophobicity were investigated by water absorption by capillarity and contact angle respectively. The corrosion degree of carbonate stone was determined by the sulfate formed on the specimens by ion chromatography. The results showed that their protective efficiency decreased after 480 h ageing. It was found that the contact - angle and protective efficiency against SO2 decreased for Pelicoat and Mellerud with the ageing time. The decreasing extent of contact angle for Pelicoat was higher than Mellerud. The surface analyses of the stone samples by SEM showed some change in superficial morphology after the ageing, suggesting that the pores became larger and the number of pores increased.