The term flat steel coating refers to the process of coating steel strips. Steel strips wound into coils are coated in a continuous process using hot-dip galvanizing or electrolytic galvanizing. The steel strips have a width of up to 1600 mm and a thickness of up to 5 mm with a coil length of up to 2000 meters. For continuous operation, they are joined together fully automatically and then rewound into coils and separated after coating.
These conventional coating processes are used on a daily basis in the mass production of many types of steel, but they also have disadvantages.
A process temperature of over 450 °C is required for hot-dip galvanizing. However, many modern steel grades are so sophisticated that they cannot withstand such a high process temperature. For example, elaborately produced high-strength steel exceeds thermal limits during hot-dip galvanizing at which it loses its material properties - the steel becomes soft and loses its tensile strength.
During electrolytic galvanizing, hydrogen can be produced as a result of the process. The atomic hydrogen in the electrolyte reacts with the steel - it diffuses into the surface. This effect, known as hydrogen embrittlement, greatly reduces the toughness and strength of the steel. In the worst case, this can lead to cracks and resulting fractures, especially in high-strength steels.
The vacuum coating process developed by NEOVAC is a much more environmentally friendly process and eliminates the risks of hot-dip galvanizing or electrolytic galvanizing.