Difference Between Acid and Alkaline Galvanizing in Molten Zinc
Author: Robby
The distinction between acid and alkaline galvanizing in molten zinc is not actually directly involved, as these two types of galvanizing are primarily applied in the electroplating process, not at the molten zinc stage. However, it is possible to discuss the differences between acid and alkaline galvanizing from the electroplating point of view in terms of layer formation, bath properties, coating characteristics and environmental impact.
Nature of the plating solution
Acid zinc plating: The main use of sulfuric acid or hydrochloric acid zinc as a source of zinc, adding some galvanizing additives to improve the brightness of the coating. Acidic galvanizing solutions have a low pH value, usually 4-6.
Alkaline galvanizing: An alkaline solution is used with zinc oxide as the main zinc source, and sodium hydroxide, galvanizing additives and some stabilizers are usually added to form a stable plating environment. Alkaline plating solutions have a higher pH, usually above 12.
Plating Characteristics
Acid zinc plating: Usually forms a coating on the metal surface relatively quickly, and the resulting coating is usually thin and bright, but may be slightly less flexible and corrosion-resistant than alkaline plating.
Alkaline galvanizing: Due to the fine and dense zinc particles in the bath, this process produces a fine, uniformly distributed coating with good adhesion and high corrosion resistance.
Production efficiency
Acid zinc plating: Due to its fast coating growth rate, efficient production can be achieved, especially economical when working with small parts.
Alkaline galvanizing: A relatively slow process with a low current density, making it suitable for parts requiring thicker layers.
Environmental effects
Acid Galvanizing: Acid solutions are more corrosive and can be more damaging to equipment and the environment, so more stringent waste disposal and environmental protection measures are required.
Alkaline galvanizing: Cyanide-free alkaline galvanizing uses a galvanizing additive that is more environmentally friendly in comparison and contains no heavy metals, making it less of a burden on the environment.
In summary, acidic and alkaline galvanizing are not directly applied in the molten zinc process, but in the electroplating process they differ significantly in terms of the nature of the bath, the characteristics of the coating, the productivity and the environmental impact. The choice of which galvanizing method to use depends on the specific application, product requirements, and environmental and productivity considerations.