With the development of modern industry, military, aerospace technology, etc., the strength of steel used is getting higher and higher, and the higher the strength, the more sensitive it is to impurity ions. At higher temperatures, steel corrodes faster. In order to avoid the failure of steel, it is an effective method to use high temperature resistant paint for protection. It is widely used because of its convenient construction and low cost. High temperature resistant coatings generally refer to coatings that do not fall off when the paint film is above 200°C and can still maintain appropriate physical and mechanical properties. Its protection mechanism can be roughly classified into two types: one is to use the compactness of the coating to prevent the corrosive medium outside the coating from invading the substrate, and the other is to rely on anti-corrosion pigments and fillers to inhibit corrosion. These two functions complement each other and play a protective role together.
Common silicone high-temperature coatings mainly focus on high-temperature resistance, but they have problems such as poor adhesion and corrosion resistance, and some special high-temperature equipment have very strict requirements on the anti-corrosion performance of high-temperature resistant coatings. Therefore, when designing the formulation of high-temperature resistant coatings, it is necessary to comprehensively consider the mechanical properties, heat resistance and anti-corrosion properties of the paint film. Evenly, then grind to the specified fineness with a sand mill, add solvent to disperse, filter, and then get component one of the finished coating; component two is polyamide resin; component three is aluminum powder paste. Its weight ratio is 100:3-10:10-20. Coating preparation Coating preparation includes substrate treatment, coating application and coating curing. Substrate treatment: Degrease the tin plate with an organic solvent, polish it to remove rust, then clean it with a solvent, and dry it.
Coating construction: Prepare the components of the coating according to the specified ratio, stir evenly, air spray and brush on the tin plate, and then proceed to the next construction after the surface is dry. Coating thickness is controlled at 40pm to 80pm. Coating curing: Put the finished tinplate plate in an oven, heat up to a certain temperature, keep it for a certain period of time, take it out, cool it to room temperature, and conduct a performance test. The heat resistance is tested according to GBT/1735-2009. Put the tin plate test piece coated with high temperature resistant paint into the muffle furnace, and rise from room temperature to phosphate pigment, etc. We choose zinc phosphate and aluminum tripolyphosphate to test, and these two phosphates have little effect on the heat resistance of the coating. Zinc phosphate mainly inhibits initial corrosion, while aluminum tripolyphosphate inhibits existing corrosion. Utilizing the synergistic effect between the two, the corrosion resistance of the coating can be improved while reducing the dosage. Figure 1 shows the effect of the amount of phosphate on the salt spray resistance of the coating.
In this study, talcum powder, mica, precipitated barium sulfate, and light calcium carbonate were used as fillers. According to the characteristics of pigments and fillers, the pigments and fillers that are commonly used and stable in quality and performance are selected, and the amount and proportion of fillers are determined through experiments. Selection of additives After the coating is applied, due to the different diameter-thickness ratios of the aluminum flakes in the aluminum powder paste and the different treatment methods, although there is a certain orientation in the coating, there is still a large proportion of the alignment direction. Inconsistent, which will reduce the compactness of the coating and the barrier properties to impurity particles. Using a certain amount of aluminum powder directional agent can improve the orientation of aluminum powder scales, improve the compactness and temperature resistance of the coating and other properties. When the amount of powder directional agent is y2c0, the coating performance is very good. Continue to increase the dosage, the improvement of the coating performance is not obvious, but it will increase the viscosity of the coating, which is not conducive to the coating construction. Other Auxiliaries In addition to the aluminum powder directional agent, the auxiliaries selected in this study are wetting and dispersing agents in order to better disperse various fillers in the resin and improve the adhesion of the silicone coating to the substrate; To improve the surface state of the coating, a leveling agent is selected; to improve the production state of the coating, a defoamer is selected; and so on. The coating has been applied to an engine component made of high-strength steel. The results show that the coating process performance is good, the temperature resistance performance meets the requirements, the mechanical properties and corrosion resistance are excellent, and the comprehensive performance meets the use requirements. Conclusion Using epoxy silicone resin as the main film-forming material, together with appropriate curing agent and functional pigments, a kind of epoxy organic silicon resin with good physical and mechanical properties and anti-corrosion properties, which can be used for a long time at 300 ℃ high temperature was prepared. Silicon high temperature resistant aluminum powder coating. Aluminum powder can improve the high temperature resistance and compactness of the coating, and the dosage is 10% to 20%. When using y2c0, the effect is very good. Compound phosphate can improve the salt spray resistance of the coating, and the salt spray resistance of the coating increases with the increase of phosphate addition. Limited by the ratio of pigment to base in the coating, when the amount of phosphate is 10% to 20%, the overall performance of the coating is better.
