Process for sealing pores in molded product, and bonded magnet with pores sealed by the process

Abstract

A molded product having pores in its surface, an inorganic powder, a fat and oil and media are placed into a treating vessel, and a kinetic energy is supplied to the contents of the treating vessel, thereby forcing the inorganic powder into the pores and hardening it in the pores. In another process, a molded product having pores in its surface and an inorganic powder producing material are placed into a treating vessel, and a kinetic energy is supplied to the contents of the treating vessel, thereby forcing an inorganic powder produced from the inorganic powder producing material into the pores and hardening it in the pores. The inorganic powder producing material performs a role of producing an inorganic powder by the collision of pieces of the inorganic powder producing material against one another, against the molded product and against the inner wall of the vessel, and a role as media for forcing the produced inorganic powder into the pores. Thus, a pore sealing effect can be achieved by cooperation of these roles. Therefore, the process according to the present invention can be carried out selectively and simply in a dry manner for the pores in the molded product to exhibit a pore sealing effect. Then, a corrosion-resistant film such as a plated film having dimensional accuracy can be formed on the surface of the molded product in a subsequent step without exertion of an influence to the surface accuracy of the molded product.