| 摘要 |
In known processes for the continuous thermal treatment or reduction of substances, the graphite crucibles are as a rule pushed through the oven space horizontally, the crucibles being heated indirectly. The temperature attainable in such a procedure is limited. The crucibles are subject to considerable abrasion. At the same time, the consumption of energy is high. The novel process and the corresponding device are intended to avoid these disadvantages and permit any desired temperature level up to 3500 DEG C to be attained using a freely selectable heating rate. The graphite crucibles are placed one on the other in the form of a train and pushed vertically through the oven from the bottom upwards. The crucible train is heated by direct resistance heating. Inside the oven space, the crucible train is surrounded by granular carbon material flowing in countercurrent. This serves for the exchange of heat in the upper and lower oven zones, for the transfer of current from the electrodes to the train and for heat insulation in the high temperature region of the oven. Exact control of the temperature can be carried out by means of the current density and the speeds of the crucible train and the carbon material. Continuous preparation of carbides, nitrides or borides. |
