Cold galvanizing is a process for preserving the surface of workpieces by electrochemical principles.
Cold galvanizing is also called electro-galvanizing. It is the use of electrolyzing equipment to remove the oil, acid-wash and put it into the solution of zinc salt, and connect the negative electrode of the electrolysis equipment. Place the zinc plate on the opposite side of the pipe and connect it to the electrolysis equipment. The positive pole is connected to the power source, and a layer of zinc is deposited on the pipe member by the current moving from the positive electrode to the negative electrode. The cold-plated pipe member is processed and then galvanized.
Cold-galvanized coatings are mainly anti-corrosion by electrochemical principle. Therefore, it is necessary to ensure sufficient contact between the zinc powder and the steel, and the electrode potential difference is generated, so the surface treatment of the steel is very important.
Like heavy-duty anti-corrosion coatings, cold-galvanizing production and painting projects are also related to environmental protection and occupational health and safety of construction workers and the public. Therefore, environmental protection is also the main development direction of cold-galvanizing. Cold galvanized materials have excellent environmental performance, mainly reflected in the following four aspects:
(1) The composition does not contain heavy metals such as Ph, cr, and Hg;
(2) It belongs to thick film type material and has good thixotropic properties. After fully stirring, it can be applied with little or no diluent. Since the content of cold-galvanized solids is as high as 77%, a single airless spray can obtain a higher film thickness, reduce the amount of organic solvent volatilization, and reduce drying energy consumption, which are beneficial to environmental protection.
(3) Tests have proved that most of the cold-dip galvanizing solvents and diluents do not contain toxic organic solvents such as toluene, ketones and halogenated hydrocarbons.
(4) Cold galvanizing is the best material to replace hot dip galvanizing and arc (hot) zinc blasting. It is more effective in reducing three wastes, reducing energy consumption and improving the social benefits of environmental protection.