Preparation And Performance Study Of Composite Coatings Based On Solid Waste Fly Ash-based Zeolite

Corrosion protection of metals and the reuse of fly ash are two hot research topics in the industry.Metal corrosion not only causes significant economic losses and waste of resources,but also poses a threat to human safety.With industrial development,the accumulation of solid waste,such as fly ash,has become increasingly serious.In order to improve the utilization rate of fly ash and reduce the adverse effects of metal corrosion on society,this study applies fly ash-based zeolite as a filler in coatings.The uniform pore structure of zeolite and the organic-inorganic interpenetrating network constructed by resin can enhance the interfacial strength between inorganic fillers and resin.Moreover,the micro-nanostructure formed by the addition of zeolite in the matrix surface can create an air layer at the interface,further blocking direct contact between metal and the corrosive environment.Therefore,this coating is suitable for constructing metal anti-corrosion coatings.This paper aims to design fly ash-based zeolite functional fillers with significant corrosion protection and shielding effects to achieve high value-added utilization of fly ash while solving the problem of metal corrosion.The main research contents are as follows:（1）First,using fly ash from power plant solid waste as raw material,pretreatment methods such as acid washing and alkali fusion were used to synthesize zeolite successfully through hydrothermal synthesis.In addition,a series of zeolite/phenyl-oxadiazole resin composite coatings with different ratios were prepared using the rough surface,porous structure,and excellent mechanical and thermal properties of zeolite.The uniform pore structure of zeolite can form an organic-inorganic interpenetrating network with phenyl-oxadiazole resin,which enhances the interfacial strength between inorganic fillers and resin,making the coating exhibit excellent shielding and wear resistance.The results show that the surface roughness of the BA3 coating with 20%zeolite addition is Ra=1.225μm,and the corresponding water contact angle（WCA）is as high as 150.4°±0.9°.The surface wettability changes from hydrophobicity to superhydrophobicity.The impedance value is as high as 4.118×10⁷Ω,which is three orders of magnitude higher than that of the single-component phenyl-oxadiazole BA1 coating.This work provides an effective method for preparing environmentally friendly anti-corrosion coatings with good mechanical properties by enhancing the interfacial strength between inorganic fillers and resin.（2）By simple double-layer spraying,a new type of superhydrophobic composite coating with a dual-layer gradient structure was prepared using bisphenol A aniline-type benzoxazine as the matrix and fly ash-based zeolite as the inorganic filler.The upper layer of the coating,with a low concentration of molecular sieve（20%）,together with the resin,constructed a superhydrophobic coating that formed an air layer when in contact with liquid,further preventing direct contact between the metal and the corrosive environment.On the other hand,the lower layer of the coating,with a high concentration of inorganic particles and resin,had a dual physical-chemical effect that improved the adhesion of the coating to the metal substrate.The results showed that the B/A coating exhibited excellent superhydrophobic properties,with a surface roughness of Ra=1.335μm,a water contact angle（WCA）as high as 158.8°±0.9°,and good anti-fouling properties against common pollutants.The coating’s impedance value was as high as 2.677×10⁸Ω,which was four orders of magnitude larger than that of the single-component benzoxazine B coating,significantly improving its corrosion resistance.The comprehensive performance of the coating described in this work has important value for applications such as metal corrosion protection,and the discussed structure-performance relationship is expected to provide useful references for the preparation of high-performance coatings.（3）A well-dispersed new type of three-dimensional network thermal conductive filler A-r was successfully prepared by wet ball milling of fly ash-based zeolite and graphene,and was used to prepare a high-performance thermal conductive and anticorrosive coating with excellent thermal conductivity.On the one hand,the addition of graphene layers in the coating can effectively prolong the corrosion medium infiltration path and improve the corrosion resistance of the coating.On the other hand,after uniform loading of zeolite on the surface of graphene,the nearly insulated zeolite particles isolate the direct contact between graphene and metal as well as between graphene,thus avoiding the formation of corrosion microcells and providing more durable and effective protection.The results show that the water contact angle of A-r-2 coating is as high as 129.8±0.2°,and the rough papillary structure on its surface improves the hydrophobicity of the coating.Compared with the single-component benzoxazine resin coating,the thermal conductivity of the A-r-1 and A-r-2 composite coatings was increased by 110.9%and 676.1%,respectively,reaching 0.424 and 1.561 W·m^-1 K^-1.At the same time,the thermal conductivity of the A-r-2 coating was increased by 159.7%compared with the same content of r GO coating,and its impedance value was as high as2.433×10⁹Ω,which is 5 orders of magnitude higher than that of the single-component benzoxazine B coating,greatly enhancing the anticorrosive performance.The three-dimensional network filler prepared in this work can not only improve the thermal conductivity of the coating,but also provide an excellent corrosion shielding layer for the coating.Its efficient heat dissipation and anticorrosive properties are of great significance for ensuring the operating efficiency,reliability,and service life of equipment.