LIGHT GUIDING UNIT FOR TRANSMITTING THERMAL RADIATION FROM THE MELT TO A PYROMETER

摘要

A light guiding unit comprises coaxially located light forming (1) and light transmitting (2) rods, made of a transparent refractory corrosion resistant material, for example, synthetic corundum. The length of the rod (1) is equal to the thickness t1 of a metallized layer of a lining (4) whereas the length of the rod (2) is not less than the thickness t2 of the other part of the lining (4). The rods (1) and (2) are connected to each other through a protecting bushing (7), made of a material which is plastic at the working temperature of the lining (4), and are placed inside a tube (3). The tube (3) is filled along the rod (1) with a refractory material (8) the sintering point of which is not higher than that of the lining (4) whereas its resistance against the action of the melt products is the same as that of the lining (4). At the working temperature of the lining (4) the material (8) has essentially the same linear expansion coefficient as that of the rods (1) and (2) and forms a viscous mass which is not alloyable with the rod (1). The silicon oxide powder may be used as the material (8). The tube (3) is eilled, along the rod (2) with a refractory material (9) the sintering point of which is above the working temperature of the lining (4) and than its sintering point, that refractory material being, in particular, the corundum powder.