Hot dip galvanizing is the reaction between molten metal and iron matrix to produce alloy layer, so as to combine the matrix and coating. Hot dip galvanizing is to pickle the steel parts first. In order to remove the iron oxide on the steel surface, after pickling, it is cleaned in the tank of ammonium chloride or zinc chloride aqueous solution or the mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to the hot dip galvanizing tank.
Hot dip galvanizing has the advantages of uniform coating, strong adhesion and long service time. Special door and window single handle quick opening and closing steel watertight door has a variety of processes for cold galvanizing, that is, electroplating. Generally speaking, it is the process of cleaning, electroplating and passivation. The color dullness refers to the color of the cold plating tube, which belongs to zincate galvanization. After passivation, the surface of the parts is red and green, slightly yellow (Cr + 6 red, Cr + 3 green), and purple can not appear (the appearance indicates that the passivation film is loose). The simple method is to rub back and forth on the surface of the parts with your fingers for several times, and there can be no color change (loss).
The common process methods for forming "zinc protection" layer include spraying and coating inorganic zinc rich coating or epoxy zinc rich coating. That is, the silver paint mentioned above. Among them, the fundamental difference between marine doors is that the coating thickness varies greatly, and the thickness of electro galvanized layer is generally only 20 ~ 30 μ m. The thickness of sprayed zinc coating is generally 100 μ M, the thickness of the galvanized layer is generally 200 μ M or so.
However, in any process, the thickness of the coating is also different, and the strict detection is still based on numbers. A ship with a closed door to prevent rain from entering. General marine weathertight doors are divided into steel doors and aluminum doors.
According to their functions and use characteristics, marine doors can be divided into: watertight doors (watertight doors, weathertight doors, airtight doors, choke valves), fire doors, shielded doors (Marine copper valve sound doors, electromagnetic shielded doors, nuclear shielded doors), non secret doors and cold storage doors.
