Heat radiation effect of anodically oxidized zinc-nickel electroplated steel sheet

A hexavalent chromium-free black-colored steel sheet (HCFBCS sheet) with high corrosion resistance, high surface electrical conductivity, and high emissivity was developed (4). In the HCFBCS manufacturing process, a Zn-Ni alloy electroplated steel strip is anodically treated in an aqueous solution containing Na2SO4 as a supporting salt and NaClO3 as an oxidizing agent (5-7). The emissivity of HCFBCS is more than ten times higher than that of conventional Zn-Ni alloy electroplated steel sheets, In experiments with a simple test box constructed of HCFBCS, the high surface emissivity of the new material promoted radiant heat transfer though the box wall, reducing the rise in internal temperature in the box under a constant internal heat input.