| 摘要 |
PURPOSE:To check the deterioration of the magnetic characteristic of metal powder by a method wherein after the amount of titanium is deposited uniformly on the surfaces of needle-like alpha-iron oxide particles in a hydrated titanium oxide type, washing, filtering and drying are performed, and then reduction by heating is applied in a hydrogen atmospheric gas stream. CONSTITUTION:After titanate-an aqueous solution of urea is added to needle-like oxy iron hydroxde or slurry of needle-like alpha-iron oxide obtained according to thermal decomposition of needle-like oxy iron hydroxide, ammonium and titanate generated according to decomposition by heating slurry are made to react to deposite uniformly titanium on the surfaces of needle-like alpha-iron oxide particles in the type of hydrated titanium oxide. The depositing quantity of hydrated titanium oxide is made to 1wt% or more and 6wt% or less converting into titanium oxide in relation to the amount of iron in alpha-iron oxide. Moreover, surface treatment is performed according to silica or alumina of the quantity of 1wt% or more and 5wt% or less, or silica and alumina of the sum total quantity of 1wt% or more and 8wt% or less in relation to the amount of iron in needle-like alpha-iron oxide. Then after washing, filtering and drying are performed, it is reduced by heating in a hydrogen atmospheric stream, and deterioration of the magnetic characteristic can be checked. |
