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The aluminum coil is treated by passivation and pressure spraying
- 2017-09-15 09:14 -
Aluminum coils need to be pretreated before they are rolled to ensure the cleanliness of the aluminium coil surface so as to avoid the presence of residual grease and lubricant on the surface and affect the painting and use.
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1, the aluminum coil was passivated. Passivation treatment is pressurized by spraying, dipping or roller to form passivation agent conversion film on the surface of the substrate. The general use of pressurized spray, mud passivation liquid produced in the use process tend to plug holes, thus affecting the spray effect.
Although the way of dipping to solve this problem, but the consumption of passivation solution greatly. The above two methods need to flush the passivation of excess fluid in the actual operation, will produce waste water purification and recovery, roll coating is the best way of passive construction, coated with a uniform, economical and practical, do not need to leaching etc. generally use aluminum oxide / chromate treatment agent, the treatment agent containing chromate, chromic acid, phosphate and fluoride. The accelerator and molybdate phosphate treatment agent must be added, otherwise it can not be used for food and beverage processing with aluminum.
2, can use the hot water to the aluminum coil cleaning. Hot water cleaning is the main substrate surface residual degreasing agent to clean, to ensure that these residues can be dissolved, to prevent the degreasing agent cause two pollution on the substrate. Using way for immersion and spray brushing way. The best water hardness is not too high. Otherwise, the water will generate in the mineral substrate surface ore spot.
3, hot alkaline degreasing due to pre coated wire speed faster, so the degreasing agent general high concentration degreasing agent typically contains sodium hydroxide (NaOH), sodium carbonate (Na2Co3) and water glass (Na2SiO3) and phosphate group. Hot alkali degreasing process includes two steps to ensure aluminum substrate clean the surface, and the use of spray and brushing way.