| 摘要 |
<p>1,227,166. Black Fe-Cr oxide pigment. FARBENFABRIKEN BAYER A.G. 15 July, 1968 [13 July, 1967], No. 33604/68. Heading ClM. A black enamel and ceramic colouring substance has a corundum structure and a molar composition substantially according to the following formula: Fe 2 O 3 .(0À7-1À0)Cr 2 O 3 and a particle size of from 0À1 to 60 microns. The X-ray powder exposure with Cr radiation, 2.2909 A, has the following intensive d-values in Angstrom units:-3À65, 2À65, 2À2, 1À85, 1À7, 1À5, 1À45, 1À3, 1À25. It is prepared by annealing at a temperature of from 1000‹ to 1300‹ C. a mixture of oxides and/or oxide-forming compounds of iron, chromium, sodium and phosphorus, which contains, per gram-atom of iron, the following constituents: 0À7 to 1.0 gram-atom of Cr, 0À005 to 0.2 gram-atom of sodium, 0.005 to 0.05 gramatom of phosphorus, and grinding, washing and drying the resulting annealed material. The oxide forming compounds may be heat-decomposable hydroxides, acids or salts of Fe, Cr, Na and P such as iron hydroxides, iron sulphates, iron phosphates, iron chromates, chromium hydroxides, chromic acid; ammonium chromate, sodium chromates, chromium sulphate, chromium phosphates, sodium hydroxide, sodium carbonate, sodium nitrite, sodium nitrate, sodium chloride, sodium phosphates, phosphoric acid or any mixture thereof. Can be used with clouding agents such as oxides of zirconium or antimony or of zirconium silicate to give grey enamels and glazings.</p> |
