PURPOSE: To improve corrosion resistance of a container, and prevent deterioration of battery performance by flame coating W to a surface of a Cr plating layer provided on an inner surface of a positive electrode container of Ni, providing an Ni-P plating layer on the surface, applying heat treatment, and forming a mutual diffusion layer between Ni and flame coated W.
CONSTITUTION: A Cr plating layer 10μm thick is formed on a surface of an Ni base material for a positive electrode container for a sodium molten-salt secondary battery in an electroless plating method. Flame coating of W about 80μm thick is formed on the surface using a beam exposure flame coating method. Next, it is heated at 900°C for 5min., in a vacuum heating furnace. An Ni-P plating layer on the surface of the W flame coating is fused by heat treatment to invade inside through pores in the W coating to close the pores. Ni-P invading into the coating is mutually diffused with the W coating to form a dense coating. In addition, the Cr plating layer provided between the W coating and the positive electrode container material restricts diffusion of the positive electrode container material (Ni) to the W coating properly, so diffusion void generated in the positive electrode container is prevented, while diffusion layers with the positive electrode container material, Cr plating layer, and W coating are generated, thereby adhesion of the coating can be improved.
KUSANO TOYOAKI
NOTOMI HIROSHI
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