In the hot galvanizing production practice, why should the zinc liquid temperature be controlled reasonably?
Zinc melting point is 419. 4 ℃, zinc don't flow very much at this moment, encounter cold material easy solidification, zinc liquid temperature is too low, therefore, is not suitable for hot dip galvanizing production, on the other hand, zinc liquid temperature must not be too high, zinc liquid temperature has many disadvantages:
(1) when the temperature of zinc solution is too high, a thicker alloy layer is generated, which will deteriorate the adhesion of the coating and make it easy for the zinc layer to fall off during processing.
(2) high temperature of zinc solution accelerates the corrosion of zinc solution to galvanized equipment, such as iron zinc pot, bent neck immersed in zinc solution, submerged roll, stable roll and other equipment in zinc solution for a long time to work, when the temperature is too high, they will soon be corroded away.
(3) the high temperature of zinc solution aggravates the weight loss of iron, thereby increasing the iron content in zinc solution and reducing the luster of the coating surface and increasing the number of defects (such as zinc particles).
(4) a large number of zinc ingots were wasted, because of high temperature, the zinc solution contained more Fe and generated more zinc slag, while the main component of zinc slag (FeZnis) contained only 6.0-6.20% iron, and the remaining 93% were zinc.
Therefore, when hot galvanizing, it must be reasonable to choose and control the temperature of zinc solution.
How does galvanizing time affect the thickness of the alloy layer?
In fixed to extend the time of galvanized, galvanized temperatures is equal to increase the chance of a zinc diffusion reaction of iron, this will make the iron on the strip surface more likely to be dissolved, in short, at any temperature prolong galvanized, the weight of the iron loss will increase, especially at 500 ℃, to extend the time of galvanized, metallic iron loss increases straightly, on the other hand, in the iron zinc diffusion reaction, come down from the strip surface dissolved most of the iron and zinc in combination with iron zinc alloy layer, and adhesion on steel strip surface, therefore, to extend the thickness of the galvanizing time will result in increased.