| 摘要 |
648,525. Non-metal resistances; wire and ribbon resistances; casings, enclosures and mountings for resistances; temperature variable resistances. INCANDESCENT HEAT CO., Ltd., and HOWARD, J. R. Dec. 1, 1948, No. 31105. [Class 37] A flame or heat-sensitive resistor comprises helical electrodes of heat-resisting wire embedded within a resistance element of titanium dioxide and bonded thereto by thorium dioxide. Two platinum wires are formed as separate helices around a refractory tube having a wire-free part secured within an enclosing tube. The projecting element thus formed is immersed in a warm solution of thorium nitrate and fired. The coating of thorium dioxide so formed constitutes a bond or flux between the platinum coils and a solution of titanium dioxide into which the coils are dipped whilst still warm. Further treatment includes dipping the element in a sillimanite or alumina solution and firing at 900-1000‹ C. and then dipping in a sillimanite paste. The completed resistor is mounted in a tubular holder. In use as a furnace control element the resistor is incorporated within the main or pilot jet whereby should flame extinction occur the resistance of titanium dioxide abruptly increases to such an extent as to cause the operation of safetydevices. |
