| 摘要 |
<p>To prepare plateletlike iron oxides by hydrothermal treatment of aqueous iron(III) hydroxide or oxide hydrate suspensions in the presence of alkali metal hydroxides and of aluminium and/or silicon compounds, the process involves two stages. In the first stage the normality of the alkali metal hydroxide solution is maintained at from 0.2 to 2 N and in the second stage it is maintained at a normality increased, compared with the first stage, by from 0.2 to 2.5 N. …<??>The two-stage process according to the invention makes it possible to prepare the plateletlike hematite pigments possessing increased gloss, a greater particle diameter, improved dispersibility and specifically controllable hues.</p> |
