Surface Preparation for Metal Anti-corrosion Coating
¡¡¡¡Generally metal surface is attached with dust grease, oxide, corrosion layer, pollutant, salt or loose varnish film. Oxide is the part quite common but which is easily neglected. Oxide is a dense oxidation layer produced in steel forging under the high temperature, which is adhesive quite stably. But comparing steel, it is much brittle and is taking on negative itself, so that it may accelerate metal corrosion. |
If coating is directly applied without eliminating these materials, it shall inevitably affect adhesion and anticorrosion ability of the entire coating. Statistics have indicated that approx. 70% above paint problems are caused by improper surface preparation. Therefore, proper surface preparation is quite critical for performance manifesting of a metal anticorrosion paint system. In general, we shall proceed surface preparation according to three work steps as follows:
- Remove various loose substances
- Clean by solvent free from grease
- Prepare surface by manual or power tools or sandblasting to meet excellent paint standard
1. Cleaning by solvent
This disposal serves to remove superficial grease and other similar pollutant by means of solvent or latex. Since it can not be thoroughly removed by various manual or power tool, even by sand-blasting, solvent cleaning shall be performed prior to any other processing.
2. Cleaning by manual tool
This traditional cleaning method is used in combination of steel wire brushing, sandpaper polishing, reaming, chiseling and so on to remove loose oxide, damaged varnish film and corrosion object on steel and other surfaces, which is adopted on the condition of other disposals unavailable due to its low speed. Usually metal surface processed by this method ca
extremely high cleanness, which is only suitable for the light anticorrosion situation
3. Cleaning by power tool
This method is to remove loose oxide, damaged varnish films and rusty substance by means of portable power tools, such as rotary wire brush, grinding wheel or sand mill, air hammer or needle gun and so on. Compared with manual tools, it may achieve a higher efficiency, but it does not suit heavy anticorrosion or immersion situation
4. Sandblasting
Relative active metal is selected to transfer original anode steel to cathode, so as to control its corrosion. In this situation, active metal as anode is inevitably corroded. Thus this method is also called sacrificial anode anticorrosion control. Rich zinc coating or galvanized iron is to make anticorrosion control by this mechanism.
5. Chemical anticorrosion
Practices have proved, regardless of in worksite or in assembly workshop, sand blasting is the most effective method to remove oxide. It is the essential processing method for successful adoption of various high performance paint |
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