Abstract
CO reduction of (Ni1−xMgx)O pellets was carried out to make the oxide particles dispersion strrengthened metal. The reduction rate of (Ni1−xMgx)O pellets was analyzed by an unreacted-core model. The microstructure of reduced mickel phase was observed by using SEM and TEM. The results are summarized as follows.
The reduction rate of the pellets with less than 5%MgO was larger than that of pure NiO, while that with more than 10%MgO was smaller. The well-sintered nickel phase was formed from pure NiO but the porous nickel was formed from (Ni1−xMgx)O solid solutions. The fine particles of magnesia were uniformly dispersed in the nickel phase reduced from (Ni1−xMgx)O. The diameter of them were 10∼40 nm. During the reduction, the increment of magnesia content in solid solution was observed at the reaction interface. The chemical reaction rate constant decreased remarkably due to the enrichment of magnesia content at the reaction interface. In addition, because this local enrichment results in an uneven distribution of reduction rate across the reaction interface, fine particles of magnesia were precipitated from this region in metallic nickel consequently.
It is seen that the metal containing the fine oxide particles can be obtained by the present method.
