In terms of phosphating treatment, the existence of phosphating film can greatly improve the adhesion of coating and has certain corrosion resistance, that is, after phosphating treatment and drying, without oil, there will be no corrosion, white rust
and other defects for a long time. At the same time, for deep drawing materials, the existence of phosphating film will greatly improve its forming ability. The phosphating film in car factory can grow in the place where the pre phosphating film is
not covered, Improve the coating process, because many users can carry out post-treatment after processing the untreated galvanized plate or hot-dip galvanized strip, such as phosphating after degreasing, but the pollution to the user's own factory
is serious, so after phosphating, the user can directly carry out coating after rinsing and degreasing with hot water, This can reduce the pressure of users on environmental protection.
This kind is generally used in household appliances, such as some washing machine shells, office supplies cabinets, and some electrical cabinets, which can be sprayed and sprayed after processing.
Another kind of phosphating treatment is more used
in automobiles. This kind of phosphating is called pre phosphating. Pre phosphating uses the self-lubricating effect of phosphating film to improve the metal flow in the processing process and is conducive to the smooth progress of forming. Therefore,
there are relatively few stamping problems in the later forming process with pre phosphating, and the probability of punching and roughening is low.
There will also be some problems in the use of phosphating products.
The first is that the
degreasing time of household appliance board is too long and the alkalinity is too strong, resulting in partial dissolution of phosphating film and local corrosion of zinc layer, which may lead to bubbles or pits in the paint layer after coating. Generally,
the countermeasures are to reduce the degreasing concentration and increase the surfactant concentration.
The second aspect is that in the automobile factory, the storage time of steel coil is too long and the surface antirust oil is difficult to
remove. Therefore, the automobile factory should control the storage time. Once there is a problem, the concentration of degreasing solution should be adjusted. The most extreme method is to polish the surface phosphating layer with sand skin.