Anticorrosion Mechanism Of New Pigments Based On Mineral Fibers And Clay

2024-T3 aluminum alloy has the advantages of high strength,low density,high thermal conductivity,excellent mechanical properties,good processability.It is widely used in chemical industry,aerospace industry,automobile manufacture,food industry,electronics,instrument and instrument industry,and marine shipbuilding industry.Chromates are highly effective anticorrosive pigments,because chromates can release chromate ions very well when encountered with water,having good corrosion inhibition effect on aluminium alloy.As people are more concerned on the environmental protection and the improvement of product performance,the development of non-toxic and low toxic anticorrosive pigments is required.It is demanded that the non-toxic and low toxic anticorrosive pigments are needed to replace chromates in primers.Based on the above background,two novel inhibitor pigments were prepared and applied to protect 2024-T3 aluminum alloy.First,the inhibitor pigments(attapulgite loaded with bismuth vanadate and montmorillonite loaded with cerous)were prepared by loading.The morphology and composition of the inhibitor pigments were characterized.Through immersion tests and electrochemical tests of the inhibitor pigments,it is proved that for attapulgite-bismuth vanadate pigment,vanadate ions can be released in sodium chloride solution and form vanadium-aluminium passivation film,inhibiting corrosion.It also proved that bismuth vanadate has better solubility and corrosion inhibition than the commercial bismuth vanadate.For montmorillonite-cerium pigment,cerium ions can be exchanged into the sodium chloride solution through ion exchange and form passivation film in the form of cerium oxide or cerium hydroxide on the surface of aluminum alloy.The results show that both of the two inhibitor pigments can have a good corrosion inhibition effect on aluminum alloy.Then,the two inhibitors pigments were containing into the epoxy coating.The performance of the two coatings were compared with the pure epoxy coating,the epoxy coating containing commercial bismuth vanadate,the epoxy coating containing montmorillonite and the epoxy coating containing attapulgite.The results of salt spray test and electrochemical impedance spectra indicate the epoxy coatings containing the two inhibitor pigments have good corrosion resistance.With the increase of content of the inhibitor pigments,the coating resistance of the epoxy coatings increases.Eventually,it is determined that the epoxy coating containing 5%attapulgite-bismuth or the epoxy coating containing 10%montmorillonite-cerium has the best corrosion resistance.