Preparation And Properties Of Organic-Inorganic Composite Siloxane Coatings For Anti-corrosion

Metallic materials have shown a wide range of applications for their excellent performance, however the metal material is susceptible to environmental, resulting in decrease of performance and life, which bringing a huge loss to the production and living. Therefore, the metal corrosion studies have been taken many attentions of the world. Currently, people use a variety of techniques to prevent the occurrence of metal corrosion, such as electrochemical protection, coating technology, manufac-turing new alloy. Among of them, the anti-corrosion coating on the metal surface is one of the most effective and commonly method.Organic polysiloxane coating is a coating material with Si-O-Si inorganic network structure, formed from hydrolysis and polymerization of organic siloxane precursor under certain conditions. It has not only a mass of silicon hydroxyl (Si-OH), which forms covalent bonds with the metal surface, but also organic groups connected with Si (methyl (-CH3), ethyl (-C2H5), propyl (-C3H7), etc.), which have good compatibility with the paint coating; at the same time, due to the high bond energy and bond length of Si-O, performance of coatings, such as environmental security, non-toxic, mechanical strength, heat resistance, weather resistance, is far better than other anticorrosive materials. Therefore, the siloxane coating can be used as an excellent anti-corrosion protective coating on the metal surface, in particular, it can be used as anti-corrosion coating when the ambient temperature is high. Currently, the research reports of this aspect are rarely both at home and abroad. And for the preparation of the silicone coating, the present research mostly begins with the preparation of oxide sols which prepared from the metal alkoxide, which costs a lot and has a relatively complex process.Firstly, this paper reviewed the research progress of anti-corrosion coatings for metal materials and silicone coating. On this basis, siloxane coatings were prepared from the hydrolytic polymerization of siloxane monomer in silica sols and alumina sols by sol-gel nano-composite method. Then self-repairing performance, room temperature curing properties and hydrophobic performance of the coatings were further analyzed and researched. And industrial application of the coating was also researched. The main results are as follows: 1) Effects of precursor type and proportion, kind and amount of catalyst, reaction temperature and time, curing temperature and time on the structure and properties of silicone coating were investigated, and the preparation conditions and curing methods were determined for the optimal performance of coatings; the reaction mechanism of MTMS hydrolysis and polymerization in acidic silica sol and coating curing mechanism were discussed. The results of29Si NMR, FTIR, GPC, TG-DTA and other tests indicate that the structure of final product was mainly composed by T2and T3molecular weight and its distribution increased with the increasing of reaction time and temperature, and the coating had well heat resistance, corrosion resistance and mechanical properties;2) Silicone coatings composited with silica sols and alumina sols were prepared, and influence of alumina sols on the structure and propertis of siloxane was investigate using XPS, FTIR and so on. Effects of content of alumina sol and curing temperature on coating properties and structure were researched, and the results showed that addition of alumina sol improved the comprehensive properties of the coating, and industrial coatings with high hardness and high wear resistance were obtained on this basis;3) A room temperature cured coating was prepared with KH560and MTMS cohydrolysis in silica sols, using TEPA as curing agent. Effects of type and content the curing agent on the structure and properties of coating were investigated and the comprehensive performance of coating cured for4-d at room temperature approached that of thermal curing coatings;4) Corrosion inhibitor, cerium ions were introduced in the silicone coating using silica sol as container. The effect of cerium nitrate on the stability of sol and coating was studied. Results of EIS and SEM-EDX implied that the coating presented self-repairing ability;5) Composite silicone coatings were prepared with OH-PDMS and TFPTMS as modifier, and reaults showed that the addition of the modifier improved the coating hydrophobic property, but reducd the mechanical properties of the coating.