Preparation And Properties Of Si₃N₄-GO/Solvent-free Silicone Modified Epoxy Composite Coatings

With the rapid development of the marine economy,the problem of marine corrosion has become increasingly prominent.Therefore,it is of great significance to study anti-corrosion coatings suitable for use in the marine environment.Solvent-free epoxy coating not only has strong anti-corrosion ability,strong adhesion,high hardness and excellent wear resistance,but also has the advantages of environmental protection and pollution-free,so it is an anti-corrosion coating with important application prospects.In this paper,silicone oil was used to modify epoxy resin,and stable Si?O and Si?C bonds were introduced into the structure of epoxy resin,which could reduce the disadvantages of poor weatherability,low fracture energy,low hydrophobicity and low impact resistance of the film.In addition,functionalized nano-Si3N4 was loaded on graphene oxide with silane coupling agent to obtain Si3N4-GO hybrid,and the hybrid was added into the self-made solvent-free silicone modified epoxy coating system,resulting in a composite coating with excellent comprehensive performance?The main work and achievements of this paper are as follows:?1?The effects of silicone oil types on the properties of modified resins and their coatings were explored.The epoxy resin was modified by hydrogen-containing silicone oil,side chain olefin silicone oil,linear olefin silicone oil,hydroxy silicone oil or amino silicone oil,and the molecular structure of the modified resin was characterized by infrared spectroscopy,epoxy value and molecular weight distribution.The effects of different types of silicone oil on the film properties were investigated by mechanical property test,contact angle test and EIS test.Finally,amino silicone oil was selected as the modifier of epoxy resin.?2?The effects of amino silicone oil content on the properties of modified resins and their coatings were explored.By changing the ratio of epoxy resin to amino silicone oil,comparing and analyzing the epoxy value and molecular weight of the product,and the influence of silicone oil content on the properties of modified resin and its coating film was further investigated.It was found that with the increase of amino silicone oil content,the hydrophobicity and thermal stability of the obtained coating film gradually increased,and when the content of amino silicone oil was more,the coating film appeared self-layering phenomenon.When the amino silicone oil was excessive,the porosity of the coating film was increased due to the poor compatibility of the system,thereby affecting the mechanical properties and corrosion resistance of the coating film.The optimum mass ratio of epoxy resin to amino silicone oil was 8:2.?3?The Si₃N₄-GO hybrid was prepared and added to the self-made coating system to prepare a Si₃N₄-GO/solvent-free silicone modified epoxy composite coating.First,the Si3N4 and GO were modified by 3-aminopropyltriethoxysilane?KH-550?and 3-glycidoxypropyltrimethoxysilane?KH-560?to obtain KSi3N4 and KGO,Thereby fixing silicon nitride?Si₃N₄?on the graphene oxide?GO?sheet.Then the effect of the mass ratio of KSi₃N₄ and KGO on the dispersibility of hybrids was investigated,and the optimal mass ratio of KSi₃N₄ to KGO was determined to be 2:1.Then different amounts of Si₃N₄-GO hybrids were added to the previously prepared solvent-free silicone modified epoxy coatings,and the effects of the hybrid content on the properties of the coating system were investigated,and determined that the optimal addition amount of Si₃N₄-GO hybrid was 0.5wt%.Finally,by comparing the properties and morphologies of the coating film with the same content of Si₃N₄/GO mixture and Si3N4-GO hybrid,it was found that the chemical compounding method can effectively reduce the occurrence of Si₃N₄ and GO agglomeration,thereby reducing the occurrence of coating film defects.