Kuumagalvanoinnin

Kuumagalvanoinnin, also known as hot-dip galvanizing, is a process of applying a protective zinc coating to steel or iron to prevent rusting. The process involves immersing the fabricated steel or iron into a bath of molten zinc at a high temperature, typically around 450 degrees Celsius. Before the immersion, the steel is cleaned through a three-step process: degreasing, pickling in acid to remove mill scale and rust, and fluxing to ensure a clean surface for zinc adhesion.

When the steel is submerged in the molten zinc, a metallurgical reaction occurs, forming a series of zinc-iron alloy layers. The outermost layer is nearly pure zinc, which provides sacrificial protection. If the coating is scratched, exposing the base metal, the zinc will corrode preferentially, protecting the steel from rusting. This process creates a durable, corrosion-resistant finish that can last for many decades in various environments.

Hot-dip galvanizing is widely used for a variety of applications, including structural steel for buildings and bridges, guardrails, automotive parts, and outdoor furniture. The thickness and uniformity of the coating depend on the steel's surface condition, the temperature of the zinc bath, and the immersion time. The coating is typically gray and matte in appearance. The process is cost-effective for large-scale production and provides a long service life, reducing the need for frequent maintenance and replacement.