| 摘要 |
<p>1,260,646. Producing iron alloy powder by reduction; coating with silver. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 3 April, 1970 [8 April, 1969], No. 15964/70. Heading H1H. [Also in Divisions C1 and C7] A magnetically stable iron powder containing between 0À5 and 150 Ag atoms per 1000 Fe atoms for magnetic recording is prepared by depositing on finely-divided iron oxide (hydrate), e.g. acicular particles ofα-FeOOH orγ-Fe 2 O 3 powder, at least one Ag compound, e.g. AgNO 3 and/or metallic Ag, reducing the iron oxide (hydrate) with a gaseous reducing agent, e.g. H 2 at 350‹ C. or below, and stabilizing the iron powder obtained, e.g. by immersing in dioxane, acetone, or ethanol and removing the adhering liquid. Preferably the iron oxide (hydrate) powder is suspended in a solution of AgNO 3 in ethanol or acetone which is evaporated. Alternatively, Ag may be deposited on to the powder from a solution of AgNO 3 to which is added formaldehyde solution and triethanolamine; or a colloidal Ag solution (sol) may be used, the liquid being separated by evaporation, centrifuging or filtering. Tin-containingα- FeOOH particles may be prepared by adding NaOH solution to FeSO 4 solution, then SnCl 2 solution to the resulting mixed solution, and passing air therethrough to precipitate the particles. The saturation magnetization of the particles is, after exposure to air for 24 hours, at least 90% of that of the freshly prepared particles.</p> |
