| 摘要 |
<p>Mfr. of acicular goethite, comprises adding zinc salt and alkali to aq. ferrous salt soln. to adjust the soln. to above pH 11, pptn. of ferrous hydroxide, adjusting proportion of anion to ferrous ion to below 1, adding sodium chlorate or potassium chlorate, and carrying out oxidn. reaction at below 80 deg.C. The process reduces reaction time and gives acicular goethite having small particle size. In an example, to 1.0L of water there were dissolved 167 g of FeSO4.7H2O and 0.86g of ZnSO4.7H2O, and 168g. of NaOH and water added such that total volume becomes 1.5L. The soln. was allowed to stand for 6h. to form ppte. of ferrous hydroxide. 750mL of supernatant liquid was removed, by which proportion of anion to ferrous ion was adjusted to below 1. Next, to this, there were added 12.3 g of potassium chlorate and 0.37g of sodium silicate soln. and added water such that total vol. becomes 1.5L. The soln. was allowed to react at 50 deg. C for 8 h. The ppte. so produced had the structure of acicular goethite. The magnetic properties of the alloy obtd. by reduction of the acicular goethite (alpha-Fe(O)OH) at 400 deg.C were as follows: Hc:1450 Oe; sigma s:130 emu/g; sigma r/sigma s:0.56. (4oo).</p> |
