| 摘要 |
PURPOSE:To obtain the titled acicular crystals having narrow paticle size distribution range and being suitable as the starting material for the prepn. of ferromagnetic powder by introducing O2-contg. gas into liquid suspension obtd. by mixing aq. soln. of ferrous salt with aq. soln. of alkali contg. seed crystal dispersed therein in the presence of hydroxy carboxylic acid. CONSTITUTION:O2-contg. gas such as air is introduced into liq. suspension obtd. by mixing aq. soln. of ferrous salt such as ferrous sulphate or ferrous chloride, pref. aq. soln. of ferrous sulphate contg. fine crystals of alpha-oxy iron hydroxide having 0.05-0.15mum major axial length and 3-5 axial ratio as seed crystal, with aq. soln. of alkali such as NaOH or KOH, adjusting the equivalent R of the alkali to the ferrous salt to >=1.0 and adding hydroxy carboxylic acid or its salt or its ester to the liquid suspension. The reaction is thus carried out and aimed acicular crystals of alpha-oxy iron hydroxide are obtd. |
