| 摘要 |
811,375. Electric heating resistors. KANTHAL, A. B. July 9, 1956 [July 11, 1955, June 25, 1956], No 21236/56. Class 39(3) A mounting arrangement for electric resistance heating elements composed substantially of suicides operating at temperatures above 1000‹C. is characterized in that the element is loosely supported on a bed which is only in partial contact with the element and which consists of relatively movable grains of a refractory and electrically insulating material which is chemically resistant to the material of the element at the operating temperature concerned. The resistance element may consist of molybdenum silicide, possibly with a residue of oxides, carbides, and borides. The bed material may comprise heat resistant carbides, borides, silicates, silicides, and/or oxides, e.g. silicon dioxide, silicon carbide, aluminium silicate, mullite, sillimanite, powder metallurgically produced pellets containing 15 per cent by weight of molybdenum silicide and 82 per cent silicon carbide, and pure crushed quartz. The grains of the bed are mainly spherical in shape, or at least have beaded edges and corners, and may be between 0.1 to 10 mm. in size. As shown, Fig. 1, a resistance element 7 is supported by and is halfway embedded in a bed 6 of aluminium silicate which is disposed on the bottom 1 of a furnace. The resistance 7 has relatively thick and therefore relatively cool, terminal portions 8a and 8b which pass through the side wall 2 of the furnace. In another embodiment (Figs. 3: and 4, not shown) the elements, together with the bedding material, are carried on shelves formed in the refractory wall of a furnace lining. In a further embodiment (Figs. 5 to 8, not shown) the resistance element rests on its bed in a tube which is mounted horizontally in a furnace. In Fig. 10, the lower half 40 of a refractory furnace liner 40, 41 which surrounds a ceramictube 42 defining the furnace chamber, is provided with a plurality of longitudinally extending grooves 44 which receive the straight portions of a looped element together with the granular material supporting them.
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