| 摘要 |
1,068,699. Resistors. AIR REDUCTION CO. Inc. Sept. 1, 1965 [Nov. 10, 1964], No. 37330/65. Heading H1S. A method of making an electrical resistive body comprises mixing together 15-50% by weight solid silicone resin binder (e.g. a heat condensable alkyl aryl or an alkyl silicone), 50-85% filler (including pulverized silica, mica, wollastonite, asbestos fines, or glass fibres, or mixtures of these), and up to 10% powdered electrically conductive material (e.g. calcined carbon black or graphite); shaping the resistive body by moulding; and curing the resistive body at a temperature between 400‹ C. and 525‹ C. for a period of three to fifteen minutes. The body may be cured by baking in an oven, by infra-red radiation, or by microwave, and possibly in a nitrogen atmosphere. The body may be moulded under a pressure of 20,000 lbs./sq. in. The mixture may also include up to 1% catalyst to promote silicone polymerization, e.g. quaternary ammonium compound, quaternary@amine, hexamethylenetetramine, hexamethylenetetramine ethiodide, boron trifluoride, dicyandiamide, cobalt and manganese driers, or arsenic pentoxide. The mixture may also include an internal lubricant, e.g. zinc stearate, carnauba wax, to facilitate ejection from the mould. After or during the moulding process, and before curing, the resistive body may be precured at a temperature between 150‹ and 185‹ C. for a period of fifteen to thirty minutes. The resistor having the resistive body described above may be leadless with metal ends (Fig. 2) or it may have wire leads embedded in the central resistive body which is covered with an insulating jacket (Figs. 3, 4). An apparatus for curing the resistors at a temperature of 400-525‹ C., Fig. 1, includes an endless metal conveyer belt 40, driven by a motor 22 which drives a speed reducer 24, and having openings 60 to receive the resistors 62, and two infra-red radiant heaters 64 and 66 joined by walls 67 to provide a nitrogen funnel. |
