In this paper, we attempted to develop a series of rust conversion coatings based on the compound of polyphosphoric acid and tannin through large numbers of experiments. Products with good rust conversion effects were selected to do more practical work. Macroscopical pictures and microscopical images were shown to illustrate the experimental results. The working mechanism of the rust conversion coatings was also analyzed. All the results may help to promote the development of rust conversion coatings and anti-corrosion science.
Iron is a very important material for the development of the society. Many companies and plants often stock stacks of iron or steel plates for continuous production. Well, iron and steel are very easy to be rusted. The rust not only changes the appearance of the materials but also brings problems for subsequent procedures such as spray-painting, conglutination and so on. In order to eliminate the effects of rust, people usually get rid of the rust by mechanical ways, which may call for long time work. In recent years, a new concept was put forward to remove rust from iron of steel plate: to use rust conversion reagents before painting or other working procedures. In this study, we attempted to develop a series of rust conversion coatings though a lot of experiments. In our research, two chemicals polyphosphate acid and tannin were taken as the element reagents, and glycerol, methenamine, sodium nitrite, manganese (II) chloride, and acetic acid were added at different amount to improve the quality of the coatings. The performances of series of rust conversion coating were examined through direct observation, SEM (scanning electron microscope), and salt spray test. Furthermore, paintings were combined with the converted layer very well. And it is no need to do any mechanical work after using our rust conversion coatings for pre-procession.
