| In many engineering fields,su~Ach~b a~ss ~tau~rto~am~co~tbile,Marine equipment,aerospace,etc,the service life of many metal equipment is not up to the expectation due to corrosion.At present,coating the surface of metal workpiece is one of the important means to prevent it from being eroded.Inorganic phosphate coating can be used as anticorrosive material,wear-resistant material and refractory material.It is a kind of water-based inorganic coating with little environmental pollution.Phosphate coating has attracted the attention of researchers because of its excellent comprehensive properties such as strong adhesion,corrosion resistance,high temperature resistance,and non-toxic environmental protection.This paper focuses on the question of whether phosphate inorganic coating can have both corrosion resistance and wear resistance.Aluminum phosphate coating was prepared with aluminum dihydrogen phosphate as adhesive,zinc oxide,magnesium oxide as curing agent and aluminum powder as filler.The influence of typical preparation factors such as the type of matrix steel and spraying process on the coating forming was discussed,and the optimized spraying process was obtained.Four kinds of aluminum-based coatings with different content of aluminum dihydrogen phosphate were prepared on 45 steel by air spraying,which the content of adhesives were 12%,14%,16%and 18%,respectively.The polymerization curing,microstructure and corrosion resistance of the aluminum phosphate coating were characterized by thermogravimetric analysis,scanning electron microscope(SEM),electrochemical impedance spectroscopy and polarization curve.The results showed that with the increase of the aluminum dihydrogen phosphate in aqueous aluminum phosphate coatings,the porosity of the coating was reduced,and the microstructure appeared to be dense.In addition,as the aluminum dihydrogen phosphate adhesives increased,the self-corrosion potential of the coating was increased,while the self-corrosion current density was significantly reduced,indicating the improvement of the corrosion resistance of the coating.When the content of the aluminum dihydrogen phosphate was 18%,the microstructure of the coating was extremely dense,which exhibited excellent corrosion resistance with a significant protective effect on the steel substrate.Based on optimization condition of the coating structure,the wear resistance of the coating was further studied.The wear resistance of the coating was enhanced by adding alumina micro particle.The microstructure,corrosion resistance to seawater,resistance to Marine atmosphere and wear resistance of the coating were characterized by sem,electrochemical workstation,salt spray testing machine and micro-dynamic friction and wear testing machine,and the internal relationship between corrosion resistance and wear resistance of phosphate composite coating was discussed.The results showed that,with the increase of the content of alumina,the wear volume loss of the coating was reduced gradually.As the alumina content was 40%,the the corrosion current density of the coating exhibited a lowest value,and the corrosion potential appeared to stay at a high level which the coating exhibited slightly corrosion.The coating showed both good wear resistance and excellent corrosion resistance. |
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