Is it reasonable to use epoxy zinc-rich paint as the primer for metal surfaces, with the surface treatment required to reach St2 level?

Epoxy zinc-rich primer is a coating used for the anti-corrosion protection of metal surfaces. It contains a high proportion of zinc powder, and utilizes the cathodic protection effect of zinc to protect steel structures, providing excellent rust prevention capabilities. Before using an epoxy zinc-rich primer, the quality of surface preparation on the metal is one of the key factors; it directly affects the adhesion and corrosion resistance of the coating. Standard ISO 8501-1 provides specific definitions for the levels of surface treatment of metals: – Sa level: Sandblasting – Sa1: Light sandblasting – Sa2: Moderate sandblasting – Sa2.5: Nearly white-level sandblasting – Sa3: Platinum-level sandblasting – St level: Mechanical rust removal – St2: Rough rust removal – St3: Very rough rust removal. According to this standard, St2 represents a manual cleaning method in which mechanical tools are used to remove rust, burrs, and old paint; although it can remove most of the rust, it does not require a high level of surface cleanliness or smoothness, and its standards are lower than those of St3 and Sa2.5, which is why it is considered a lower standard for surface treatment. Epoxy zinc-rich primers require good adhesion and corrosion resistance; sandblasting to a Sa2.5 level or higher is generally recommended. This is done because sandblasting can clean the surface more thoroughly, increasing its roughness and the adhesion of the coating, thereby enhancing the overall lifespan and corrosion resistance of the coating system. Therefore, if the use of epoxy zinc-rich primer is required and an expected service life of the coating of more than 5 years is desired, mechanical rust removal only to St2 level may not be sufficient. Theoretically, a higher quality surface treatment (such as Sa2.5 or a higher level of sandblasting) provides more durable and effective protection. However, the actual lifespan of the coating is also influenced by environmental factors (such as humidity, temperature, exposure to chemicals, etc.) and other components of the coating system (such as intermediate layers, topcoats, etc.). In practical applications, the level of surface treatment should be determined based on factors such as the specific working environment, engineering requirements, and cost budget, and advice from coating manufacturers should be sought to find the most suitable solution. .

Epoxy zinc-rich primers have high requirements for surface treatment.

Just follow the standard regulations. There are requirements for this epoxy zinc-rich anti-corrosion paint.

May I ask the original poster, in an environment with temperatures between 200-270°C, what materials possess good corrosion resistance?