Studies On Preparation, Stability Of Acidic Ultrafine Silica And Its Application Of Ceramic Surface Modification

Silica can be divided according to the pH: acidic silica, neutral and alkaline silicasol. In silica series of products, there is a particle size of about5nm in ultrafine silica sol,its application results in some areas is other products difficult to replace.Due to the acidic ultrafine silica having nano features, its composition is similar tothe compatibility of the ceramic body, the fired ceramic body in favor. This topic first usethe acid ultrafine silica sol made for ceramic surface modification. Acidic silica sol forsurface modified ultrafine ceramic with good anti-fouling, easy cleaning performance,compared with the conventional conventional methods, this method is applied directlyafter the acidic silica ultrafine surface of the sintered ceramic body is not change theoriginal sintering process, lower cost, and the appearance of color after firing the ceramicsintered body, without any change in color.This study uses sol-gel method, ethyl orthosilicate (TEOS) as raw materials, ethanolas the solvent, nitric acid as the catalyst, polyvinylpyrrolidone (PVP) as additive,preparation of acid ultrafine silica sol. By changing the temperature of the reaction waterbath, the reaction time, n (EtOH): n (TEOS), n (H2O): n (TEOS), n (PVP): n(TEOS),etc, select the best experimental process for n (TEOS): n (EtOH): n (H2O): n(HNO3): n (PVP)=1:6:8:0.01:5%, the reaction temperature of water bath is80℃, thereaction time was3h. Preparation specifications of the products as follows: SiO2%isabout9.8, the average particle size is about4.6nm, the pH value of2, viscosity of6.4mPa.s, stabilization for3months.Through single factor and orthogonal experiments analyze the factors of sol stability.The experimental results show that: the molar ratio of TEOS in ethanol is mostsignificant, as the system n (EtOH): n (TEOS) is increased, the gel time extendedgradually, which enhanced the stability of the sol system. With the increase of the amountof PVP, the increased amount of water was added, and the reaction time increases the pH, the gel time will be shortened after the first extension. It is concluded that the bestexperimental process for n (TEOS): n (EtOH): n (H2O): n (PVP)=1:14:8:5%, thereaction temperature is80℃, reaction time is3h.To use laboratory self-made silica sol on ceramic surface modification for test itsanti-staining, easy cleaning properties, And from the number of silica coating and solidscontent of the ceramic samples of both water absorption, surface easy to clean andstain-resistant surface to explore. The experimental results show that the optimal coatingprocess is: the number of coating for four times, the solid content of silica sol was8%.Meanwhile, without the silica surface modified ceramic samples and after surfacemodification of silica microstructure of ceramic samples were compared, the resultsshowed that: after surface modification of surface porosity ceramic samples wassignificantly reduced.