| 摘要 |
<p>1,200,856. Chromium dioxide. E. I. DU PONT DE NEMOURS & CO. 13 Feb., 1969 [13 Feb., 1968], No. 8000/69. Heading C1A. Ferromagnetic chromium dioxide particles of average length less than 1Á, average width less than 0À2 Á and average axial ratio at least 3 : 1, and incorporating chromium-containing impurities, e.g. lower oxides of chromium, are heated at 150-450‹ C. under a pressure of 0.2- 3000 atmospheres while maintaining them in an oxidizing environment, such as an oxygen, chlorine, nitrous oxide, bromine, sulphur trioxide or chromium trioxide. The ferromagnetic properties of the chromium dioxide are thereby improved. The impure chromium dioxide may be milled before heating.</p> |
