Research On Preparation And Performance Of Epoxy Anticorrosive Coating Based On PANI/SiO₂

Metal corrosion has caused huge economic losses to the national economy and people's livelihood.Applying organic coatings on the surface of metal materials is one of the commonly used anti-corrosion methods.Epoxy coating has low cost,good manufacturability and mechanical properties,and is widely used for corrosion resistance on metal surfaces.Polyaniline(PANI)is a commonly used conductive polymer,coated on the metal surface,and it can promote the formation of a passivation film on the metal surface through the oxidation-reduction reaction,so as to protect the metal surface and greatly reduce the corrosion rate.However,in practical applications,it was difficult to disperse pure PANI to epoxy resin,resulting in unsatisfactory anti-corrosion performance of composite coatings.Some researchers compounded PANI and inorganic particles,and then added them to epoxy resin to obtain good anti-corrosion effect.This paper firstly coat polyaniline on silica to prepare a core-shell structure of PANI/SiO2 particles with good dispersibility.On the one hand,the effect of different curing agents on the mechanical properties and anti-corrosion properties of epoxy coatings is studied.On the other hand,the effect of SiO2 particle size on the mechanical properties and anti-corrosion properties of epoxy coatings,is study of the specific research in this paper are as follows:(1)Using in-situ polymerization,polyaniline(PANI)was coated on the surface of 400 mesh SiO2 to prepare PANI/SiO2 particles with a core-shell structure and added to the epoxy anticorrosive coating.Using phenalkamine T-31,cardanol and polyamide 650 as curing agents to cure the epoxy coating.Using scanning electron microscopy,it was found that the epoxy coating cured by polyamide 650 had a compact structure,it was take second place by epoxy cured by cardanol.and the epoxy cured by phenalkamine T-31 had obvious micropores on the surface.The mechanical performance test of epoxy coating shows that epoxy coating cured by 650 curing agent has higher flexibility,adhesion,and impact resistance.it was take second place of epoxy coating cured by cardanol.But the epoxy coating cured with T-31 curing agent has the highest hardness.The results of the anti-corrosion performance test show that the epoxy coating cured with 650 polyamide has the best anti-corrosion performance.Soaking it in a 3.5wt%NaCl aqueous solution can still exert a good anti-corrosion effect after 30 days.(2)Using in-situ polymerization,PANI/SiO2 particles were prepared by coating polyaniline on the surface of SiO2 with different particle sizes.The coated SiO2 particles changed from white to dark green.The study of infrared spectroscopy showed that PANI had been coated on the surface of SiO2 particles.The coverage rate of PANI was studied by thermogravimetry,the results showed that coverage rate increased with the decrease of the particle size,and coverage rate of PANI of 1250 mesh SiO2 particles reached to 1.76wt%.The anticorrosive coating is prepared by adding PANI/SiO2 particles to epoxy resin coating.The study found that as the particle size of the added particles increases,it is adhesion,impact resistance and abrasion resistance of coating will further increase.The layer hardness is further reduced.epoxy coating prepared by adding 400 mesh PANI/SiO2 particles has a compact structure.PANI can also play a good role in passivating metals.The coating can still play a good anti-corrosion effect after immersing in 3.5wt%NaCl aqueous solution after 30 days.