| With the rapid development of economy and the continuous improvement of people's quality of life,as well as the introduction of national environmental policies and regulations,the environment protection and resources conservation have become a topic of common concern.In order to comply with the trend of the times,the paint products are gradually toward the direction of environment protection and resources conservation.The water-based paint products have become one of the development direction because of low VOC content.This issue is based on the project,and the purpose is to develop a green water-based rich zinc-rich aluminum coating to deal with the pollution problems created by universally application of chromium zinc and aluminum coating in marine engineering,ship bridge,petrochemical and other industries.Based on the study of water-based zinc-rich coating formula,the basic components of water-rich zinc-rich aluminum coating was determined through a series of pre-exploration experiments,appropriate metal zinc aluminum powder,binder,passivator,high boiling point organic solvent,dispersant and thickener to prepare water-rich zinc-rich aluminum coating was selected.Silane coupling agent was used in the experiment as a binder,the optimum hydrolysis conditions including silane mass fraction,hydrolysis temperature,p H of silane were explored.The five-factor orthogonal test was designed to optimize paint formula based on the main influencing factors:metal zinc-aluminum powder,binder,passivation agent,high boiling point organic solvent and dispersant,the property of coating was evaluated by appearance,adhesion and corrosion resistance of the coating.On this basis,the coating preparation process was further optimized.The corrosion resistance and impact resistance of the coating were measured by means of grid method and impact test.The surface topography,elements and composition of the coating were analyzed by SEM,EDS,EDX and XRD.The electrochemical test method was used to observe the open circuit potential change of coating during the soaking process in 5% brine,and the corrosion process during immersion was analyzed.In addition,the experiment was carried out by coating a layer of water-based sealing paint on the surface of the water-based rich zinc-rich aluminum coating to examine the change of corrosion resistance before and after the coating was sealed.Finally,the storage stability of the coating was investigated by observing the change of the appearance and viscosity of the coating with time.The optimum conditions for the hydrolysis of silane were obtained by studying the main influence factors of silane KH-560 hydrolysis.When the mass fraction of silane was 2% or 4%,the hydrolysis temperature was 30?,pH = 4,the hydrolysis degree of silane was large.To guarantee good coating adhesion,the mass fraction of silane was better to be 4%.The optimum formula was as follows: the mass fraction of metal powder was 20%,zinc powder: aluminum powder = 7:1,dispersant 1.2%,high boiling organic solvent 6%,silane hydrolysate 70%,passivator 1.8%,defoamer and thickener 0.5~1%.The passivation time was 1.5 h,the stirring time was 4.5 h,the drying process was 80 ?× 15 min,and the curing process was 280?× 30 min.The appearance of coating prepared was continuous,uniform and silver gray,coating thickness 5~7 ?m,coating adhesion level 1 class,flexibility 1mm,hardness 7 H,impact strength 50 mm,there were no obvious red rust occurred on the surface of coating after the neutral salt spray time for260 hours.After a layer of water-based sealing paint was coated on the surface of the water-based rich zinc-rich aluminum coating,the neutral salt spray test results show that there was no obvious red rust on the surface of the composite coating for 260 hours neutral salt spray test results,but blister appeared.The storage stability experiment of the coating showed that the appearance and viscosity did not change significantly after20 days of storage. |
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