Effect Of SiO₂–DDS Composite Thin Film On Hydrophobic Performance Of Enamel Surface

Recently,a lot of scientific researches about SiO₂ composite film have been carried out in many fields of inorganic and organic materials.There are a lot of researches mostly focusing on ceramics,glass,chemical fiber and metal base etc.But there is lack of relevant researches about enamel substrate.In this thesis,the current situation and trend in development of enamel products were be introduced firstly,then,we introduce and investigate many of the theories and the methods about generating hydrophobic surface and on the basis,we use the organic and inorganic nano-composite materials to build micro/nano multistage structure which is similar to super hydrophobic film on the surface of the lotus leaf by making an inorganic rough surface first and then modifying it with an organic low surface energy material.In the experimental part,a hydrophobic film on the enamel substrate was prepared by hydrothermal method with combination of the reaction kettle which can create high temperature and high pressure reaction conditions,then by using the DDS to modifying it.The hydrophobic enamel has been developed finally.The effect of different reaction time,reaction temperature,ratio of sol,the quantity of DDS on hydrophobic properties of enamels has been systematically investigated by experiments.FTIR?SEM and contact angle measurement apparatus were used to analyze the surface microstructure and hydrophobic characteristic.The results showed that when the reaction time was 12-14 hours,reaction temperature was 200?-220?,the ratio of SiO₂ acid sol and SiO₂ alkaline sol was 1:1,SiO₂ sol and AlCl₃ sol was 7:10,SiO₂ sol and ZnCl₂ sol was 1:1,the quantity of DDS was 1ml in 50 ml alcohol,the enamel surface has the best hydrophobic performance.The droplet contact angle was 150.3°.SiO₂ alkaline sol,AlCl₃ sol and ZnCl₂ sol can obviously increase the hydrophobic properties of enamel surface.They increase the surface roughness,and successfully build micro/nano multistage structure which is similar to the super hydrophobic surface of the lotus leaf.DDS plays an important role in improving hydrophobic performance because it can crosslink with inorganic particles,and reduces the surface energy.It shows by the testing that the hydrophobic film has little effect on the gloss and whiteness of enamel,and do not affect the actual looking appearance.Weathering experiment further testifies that the enamel with thin SiO₂ composite Film can maintain good hydrophobic effect for long time in the indoor environment,but more obvious declining in outdoor environment.The results of the investigation on the thesis indicated that hydrophobic easy-to-clean enamel could be prepared by hydrothermal method.Rough surface and low surface energy were two major factors to the preparation of hydrophobic surface.Therefore,the surface micro-structure and constituent determined the hydrophobicity of the enamel.