| 摘要 |
1,254,388. Manganese-zinc ferrites. NIPPON ELECTRIC CO. Ltd. 7 May, 1970 [9 May, 1969], No. 22099/70. Heading H1H. Manganese-zinc ferrites having a basic composition of 30À0 to 38À0 mol. per cent MnO, 51À0 to 57À0 mol. per cent Fe 2 O 3 and the balance ZnO contain cobalt, tin, calcium, silicon and optionally lithium in the form of oxides thereof in the quantities:-0À01 wt. per cent# Co 2 O 3 #0À5 wt. per cent, 0 wt. per cent<SnO 2 #3À2 wt. per cent, 0À02 wt. per cent #CaO #0À5 wt. per cent, 0À005 wt. per cent #SiO 2 #0À05 wt. per cent and 0 wt. per cent #Ti 2 O #0À125 wt. per cent. They may be made by mixing the constituents in a ball mill for 60 hours with alcohol as the dispersion medium, and presintering the mixture at 800‹ C. in air for 4 hours followed by press-moulding and sintering at 1180‹ C. in a nitrogen atmosphere containing 0À4% by volume of oxygen for 8 hours. |
