Protecting stainless steel by glass coating during slab reheating

A glass coating was prepared onto AISI 304 stainless steel by a slurry-spraying technique and its effects on oxidation behavior of this steel was investigated at 1250 °C in air. Results were compared with those for bare specimens. The glass coating decreased the weight gain by 98% after oxidation for 9 h, and oxidation kinetics of 304 stainless steel was changed to linear behavior due to the coating. Steel loss of the coated specimens was reduced by 1–2 orders of magnitude. Hot stage microscopic, optical, XRD and SEM-EDX analyses revealed that the as-received coating melted at high temperature, to form self-healing, homogeneous glass coating which acted as a perfect oxygen diffusion barrier and prevented the breakaway oxidation of 304 stainless steel. During cooling, the glass coating spalled because of CTE mismatch between coating and the steel. This glass coating by low-cost and easy handling method is potentially applicable during slab reheating of stainless steel.