<Original Papers>On the Formation Mechanism of Pores during the Reduction of Synthetic Wustite with Hydrogen

The present paper deals with the growing process of pores in metallic iron phase formed in synthetic wustite during the reduction with hydrogen. The results obtained are summarized as follows : (1) The microscopic examination shows that the metallic iron formed in wustite contains both porous and dense phase. It is considered that the dense phase appears as a result of the small pores being embedded by the polishing for microscopic observations. In reality, many small pores were observed in this phase by the scanning electron microscope image. (2) Oxide phase was also detected in this "dense" metallic phase. (3) The growing process of pores is considered as follows : Metallic iron phase with small pores and oxides precipitates from wustite. Pores grow continuously after the precipitation of metallic phase. Consequently, porosity and pore size change from inner part of sample to the outer surface, corresponding to the growing process of pores