Methods for treating organic substances such as oil stains on metal surfaces:

Dalian metal surface treatment, clean metal surfaces are hydrophilic, so they can be completely wetted by water. When the metal surface contains oil stains, there will be water cut off areas that are not soaked by water. Based on the principle of hydrophilicity, in addition to the simple and commonly used exhalation method and atomizer spray method, there are several detection methods as follows. Due to the hydrophilic nature of metal oxide films, most of these methods cannot detect whether the oxide film on the metal surface has completely removed.  

Long term production practice has proven that if there are organic substances such as oil stains on the metal surface, although the coating can sometimes deposit, the flatness, adhesion, and corrosion resistance of the electroplating layer are always affected by the interlayer of oil stains, and even the deposition is discontinuous, loose, and the coating peels off, resulting in the loss of practical use value. So, we must pay attention to pre-processing techniques. On the market, we commonly use three pre-treatment methods: mechanical method, chemical method, and electrochemical method. These three methods all have certain defects in product quality. At present, the "two in one" purification solution for oil and rust removal is considered a very promising pre-treatment process. Most of the quality accidents that occur in electroplating production are not caused by the electroplating process itself.

Most likely due to improper pre-treatment of metal products before plating. Especially the smoothness, adhesion, and corrosion resistance of the coating are closely related to the quality of the pre-treatment before plating. The chemical solution produces a passivation layer on the metal surface that is difficult to remove, causing a serious decrease in adhesion. For example, sodium nitrite, sodium silicate, phosphate, certain organic acids, surfactants with corrosion inhibition ability that are not easy to rinse, hexavalent chromium, formaldehyde, organic solvents with strong adsorption capacity, etc.

The core process of Dalian metal surface treatment is alkali corrosion, which determines the surface flatness and sanding quality of the profile. In order to achieve the goal of leveling mechanical patterns, it generally takes 12-15 minutes of alkali etching, with aluminum consumption reaching 40-50Kg/T and alkali consumption reaching 50Kg/T. Such high aluminum consumption not only wastes resources, but also brings serious environmental problems and increases the cost of wastewater treatment. This process has been used for over 100 years and is still in use by most aluminum factories worldwide until it was gradually replaced by acid etching in the past two years. Composed of oil removal, water washing, polishing, water washing, and water washing, the profile is placed in a polishing tank after oil removal and polished for 2-5 minutes to form a mirror surface. After water washing, it can be directly oxidized.

The core process of Dalian metal surface treatment is polishing, with grain removal and mirror finish completed in the polishing tank. Polishing has the advantages of low aluminum consumption and bright profiles, but the emission of NOx from the polishing tank causes serious environmental pollution and physical injury to operators. At the same time, factors such as expensive chemical raw material costs also restrict the promotion of this process. One of the common methods for metal corrosion prevention is to change the structure of the metal. There are many types of metals, some of which have low chemical activity and are not easily corroded by other substances. There are also some metals that can effectively improve their anti-corrosion ability when used in combination with other metals. For example, adding chromium, nickel and other materials to ordinary steel to make stainless steel can achieve good anti-corrosion effect.