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This post was last edited by Wang Wei2 on 2024-3-20 08:56. Let’s discuss the mechanism of rust-inhibiting coatings. Depending on the principle by which they interact with rust products, rust-inhibiting coatings can be divided into three types: conversion type, stabilization type, and penetration type. Transformation coatings, also known as reactive rust-inhibiting coatings, use phosphoric acid combined with xanthate or phosphoric acid combined with tannic acid as transforming agents – substances that can undergo a chemical reaction with rust to convert harmful rust into harmless complexes or chelates that provide protection. These agents are added to the coating material, which is then applied to rusty steel surfaces to form a complete protective layer with good adhesion. Transformative rust-coating is suitable for steel surfaces with a relatively uniform rust layer, free of residual scale, thick rust, and old paint, where the rust layer is thick. The advantage is its ability to convert heavy rust, with a fast conversion rate; the disadvantage is that it is difficult to determine the relationship between the thickness of the rust layer and the amount of coating required. If the acid content is low, the rust is not completely converted, while if the acid content is high, acidic substances remain in the paint film, which can corrode steel. It cannot be used as a true primer but only as a surface treatment agent. To provide corrosion protection, acid-resistant primers and topcoats must be applied additionally during application. Stable rust-coating paints achieve the purpose of rust-coated finishing by adding various rust promoters and stabilizers to the film-forming substance. Its advantages include a wide range of applicability – it can be used on steel surfaces with uneven rust, residual hard oxide scales, or old paint. It contains no toxic pigments, can be welded, and can be used directly as a primer in combination with other topcoats, eliminating the need for an additional primer. The downside is that it can only be used on steel surfaces with light rust (rust layer thickness less than 30 tma). Penetrating rust-inhibitive coatings primarily utilize the wetting and penetrating effects of the paint on loose rust. Separate the rust and enclose it in paint to prevent further corrosion. Penetrating rust-coating paints contain neither rust stabilizers nor conversion agents, and they have little chemical effect on steel; therefore, they are mainly suitable for use on steel surfaces that are severely corroded but have minimal chemical contamination. There is a large market demand for such rust-resistant coatings.