抄録
The influence of initiation of reduction and of traces of impurity oxides added specifically and dissolved in FeO on morphology of iron nucleus formed by the reduction of dense wustite with H2 gas at 670°C has been investigated. The reduction was started in two ways: (1) the sample was heated to reduction temperature in vacuo and then H2 gas was introduced to the sample at various rates, (2) the sample kept at room temperature was inserted into the H2 gas stream kept at reduction temperature.
When pure FeO was reduced in the procedure (1), porous nuclei (they are lenticular shapes and grow to form a porous layer which surface remain at the level of the sample surface) were not observed but were observed locally in the case of that H2 gas was introduced at the fastest rate. CaO favored porous nuclei particularly and MgO slightly. Al2O3 and SiO2 were unfavorable for porous nuclei. Iron nuclei precipitated in cooling period were observed on the surface of the sample when the sample containing CaO was cooled slowly after interruption of oxygen removal reaction.
When samples were reduced in the procedure (2), surfaces of all kinds of samples were covered with porous iron. The influence of impurity oxide did not appear clearly.
