The pretreatment of painting includes three parts: degreasing (degreasing), rust removal and phosphating. Phosphating is the central link, and degreasing and rust removal are the preparatory processes before phosphating. Therefore, in production practice, phosphating work must be the focus and the quality of phosphating must be taken into consideration. Rust work, pay special attention to the mutual influence between them.

Degreasing and removing rust

A high-quality phosphate coating is only formed on the surface of the workpiece where foreign matter such as oil, rust, and oxide scale has been completely removed. Because the oil stains, rust, and oxide scale remaining on the surface of the workpiece will seriously hinder the growth of the phosphating film. In addition, it will affect the adhesion, drying performance, decoration performance and corrosion resistance of the coating. Complete removal of these foreign bodies is a necessary condition for phosphating.

Oil removal and rust removal are the two basic processes before phosphating. Relatively speaking, oil is more harmful than rust, and oily workpieces will directly affect the speed of rust removal. Therefore, rust removal should be based on oil removal. However, for workpieces with less oil and more rust, the two basic processes of degreasing and derusting can be combined into one. The degreasing and derusting process can be completed in one tank at the same time, which can shorten the production line, reduce equipment investment and plant investment costs , But the processing quality is not as good as the sub-tank, which can be used when the requirements are not high. After adopting this procedure, the degreasing agent should also be used in conjunction with acidic agents and rust removers. Hydrochloric acid is still used for rust removal. Hydrochloric acid removes rust quickly, cleans thoroughly, and has a good function of removing oxide scale. It is used at room temperature. The disadvantage is that hydrochloric acid rust removal has large acid fog, which is harmful to health and serious environmental pollution.

With the development of industry, environmental protection and improvement of working conditions have become issues of common concern. Therefore, the need for environmental protection should be considered when choosing a drug. Therefore, when choosing a degreasing agent, it requires simple preparation and strong decontamination ability. It does not contain sodium hydroxide, silicate, OP emulsifier and other ingredients that are difficult to clean at room temperature. It is easy to wash at room temperature, does not contain toxic substances, and does not produce harmful gases. , Good working conditions. When choosing a rust remover, it is required to contain accelerators, corrosion inhibitors and inhibitors, which can increase the speed of rust removal, prevent over-corrosion and hydrogen embrittlement of the workpiece, and can better inhibit acid mist. Especially worthy of attention is the suppression of acid mist. The acid mist generated in the process of pickling and rust removal not only corrodes equipment and factories, pollutes the environment, but can also cause teeth corrosion, redness of the dental conjunctiva, tearing, pain, dry throat, coughing, etc. Symptoms, so the effective suppression of acid mist is not only for environmental protection, but also for the health of employees.

Considering the above requirements, after screening, the degreasing and derusting agent is formulated with the XH-16C degreasing and derusting additive of Phosphating Company and checked calculations. It is used at room temperature and the treatment time is 10-30min. It can improve the derusting speed. Prevent the workpiece from over-corrosion and hydrogen embrittlement, and can better inhibit acid mist.

Formula: XH-16C 4%+HCL (35%) 60%+H2O