BLACKENING METHOD OF NI-FE SHADOW MASK AND MESH BELT TYPE BLACKENING FURNACE THEREFOR

摘要

PURPOSE:To provide a blackening method of a Ni-Fe shadow mask and a mesh belt type blackening furnace therefor capable of forming an oxide film having an excellent emissivity in a short time. CONSTITUTION:An exhaust duct 14 is provided on a predetermined ceiling part of a blackening band 3 kept at a blackening temperature, and a charging side band 3A is laid in, for example, a mixed atmosphere of a humidly exothermic gas and air through the exhaust duct 14 to conduct a first treatment for forming an oxide film consisting of Fe2O3, Fe3O3 and FeO. On the other hand, an extracting side band 3B is laid in, for example, the atmosphere of the humidly exothermic gas to conduct a second treatment for reducing the Fe2O3 to Fe3O4. Thus, an oxide film mainly consisting of Fe3O4 is formed on the shadow mask surface.