| 摘要 |
A tubular heating element comprising a metal pipe having housed therein a heating wire and filled with insulating material, said metal pipe being air-tightly sealed at its both opening ends. To prevent metal evaporation and diffusion which will be caused from the heating wire or the inner wall of the metal pipe at a high temperature in a reduced pressure atmosphere, the wire (8) is formed of a low vapor-pressure alloy of nickel, tungsten, molybdenum or the like. The inner wall of the metal pipe (4) is further coated with a layer of a low vapor-pressure metallic material such as nickel, tungsten, molybdenum or the like, to thereby retard the rate of insulation deterioration and improve the service life and the safety. This heating element may be widely available in home appliance and in industrial use. |
