| 摘要 |
PURPOSE:To obtain gamma-ferrous oxide which is suitably used as the material for manufacture of magnetic ferrous oxide containing cobalt by a method wherein a sulfuric compound is densely formed and properly modulated by performing a dehydration process on a needle-like Geothite. CONSTITUTION:Needle-like Geothite is ordinarily manufactured from a ferrous sulfate solution by neutrarizing and oxidizing a ferrous sulfate solution at the temperature of 40-80 deg.C. Then, the grown needle-like Geothite is dehydrated by performing a dehydration process and alpha-Fe2O3 crystal is densely formed. The dehydration process is ordinarily performed by heating up the needle-like Geothite under the condition wherein air or inert gas exists. Subsequently, the alpha-Fe2- O3 crystal is densely formed by continuously heating up the above to 650- 750 deg.C under the condition wherein air or inert gas exists. With the above procedures performed, the sulfuric compound containing SO4 and the like is thermally deposited, and also voides are removed. It is important that the atmosphere at the time when the formation of crystal density is finished is maintained at 0.2-2vol% as the concentration of SOx. |
