Thermal stress for all-ceramics rolls used in molten metal to produce stable high quality galvanized steel sheet

The zinc coated steel sheet has been mostly used for automobile and other industries because of its high corrosion resistance. This paper deals with the development of new ceramics support roll used for a continuous galvanizing pot to manufacture stable galvanizing steel sheet. Usually stainless steel rolls coated by tungsten carbide are used to support and stabilize the strip in a continuous galvanizing pot, which is filled with molten zinc. However, corrosion and abrasion arise on the roll surface only in a few weeks, and causing the deterioration of quality of plating. Although developing all-ceramics rolls is most desirable, risk of fracture has to be reduced when the ceramic roll dips into molten metal. In this paper, therefore, how to reduce the thermal stress is considered when the ceramic rolls are installed in molten metal using finite volume method and finite element method. The usefulness of silicon nitride having extremely high conductivity is also discussed.