Interactions between liquid zinc and bath hardware materials in continuous galvanising lines

摘要

Immersion tests in liquid zinc at 480 deg C have been carried out on stainless steels and a low carbon steel. The austenitic stainless steel grades were attacked aggressively by molten zinc below the submerged level. There was considerably less attack and intermetallic growth on the ferritic stainless steel and ceramic coated austenitic stainless steel. Above the liquid level, an intermetallic layer formed on the surface of the stainless steels which grew steadily upwards and, in some cases, engulfed that part of the sample lying above the liquid zinc level as well as the sample holder. This phenomenon, which has been termed 'supermeniscus intermetallic climb' (SMIC), does? not appear to have been reported previously. Its occurrence can be rationalised by postulating a net decrease in the overall energy of the system, the increase in potential energy due to SMIC being less than the increase in chemical energy associated with the formation of the zinc compounds.