Preparation And Study Of Properties Of Water-based Over-rust Coating

When we protect steel by coating, the steel surface must be pretreated by some methodsbefore the conventional anti-corrosion coatings are applied on steel. Among them, thesandblasting method is the most popular and the treatment level should reach Sa2.5cleanliness level. The cost of such treatment process is about30to40percent of total cost ofcoating application, and this kind of treatment is easy to produce large amounts of dustpollution and noise pollution, especially in some special occasions such as complex steelstructure corner even can’t take advantage of the sandblasting treatment process. So, it’smeaningful to develop over-rust coating.This topic is aiming at improving the anti-corrosion performance of water-basedover-rust coating as the current water-based over-rust coating’s anti-corrosion performance isnot ideal, the resistance performance to neutral salt spray of most water-based over-rustcoating is less than200h. This topic is carried out in the rust whose thickness is less than30μm after treated by hand and the whole paper includes three parts as follows:In the first part, the rust layer and rust converter A was studied by infrared spectroscopy,scanning electron microscopy, GC-MS methods. the following results were getted: the maincomponents of rust layer from the inside to the outer are Flake ferroferric oxide, rod-likeγ-FeOOH, and dot-shaped α-FeOOH sequentially, among which the Flake ferroferric oxideand rod-like γ-FeOOH have the ability to react with rust converter, and the purpose to removefloating rust is to clean dot-shaped α-FeOOH which has no reactivity and poor adhesive force;The main components of rust converter A are isopropanol and catechol, isopropanol providesthe permeability and catechol provides rust converter function.In the second part, my work is to prepare the water-based acrylic over-rust coating, andThe influences of rust converter, anti-flash additive, anti-corrosion pigment, wetting agent andPVC on coating’s performance are studied. The results shows that film has the bestperformance when the rust converter is rust converter A and its mass fraction is5%, anti-flashadditive is Halox330, the anti-corrosion pigment is zinc phosphate and its mass fraction is7%,wetting agent is Tego520, and PVC is33%. The performance of water resistance is16d, the performance of salt water resistance is17d, and the performance of salt spray resistance is240h.In the third part, my work is to study the water-based epoxy over-rust coating. Firstly,compare the differences of epoxy group before and after epoxy curing with the ratio of10:1by infrared spectra, the result shows epoxy group is reacted almost completely; Secondly, thefilm has the best performance when its PVC is29%, that is the performance of waterresistance is17d, the performance of salt water resistance is18d, the performance of saltspray is500h. What’s more, the water-based over-rust coatings in this topic are easy to bematched by conventional water-based top coating.