Installation and fixation of crucibles

Installation and fixation of crucibles

(1) To install a crucible for a gas or fuel fired furnace, first place the crucible on the base, reserve a certain amount of crucible expansion space between the crucible and the top of the furnace wall, and fix it with materials such as wooden blocks and cardboard. Adjust the position of the burner and nozzle to align the flame with the combustion chamber, not directly with the bottom of the crucible;

(2) When installing a crucible for a rotary furnace, support bricks should be used to fix the crucible on both sides of the pouring nozzle to avoid wedging the crucible tightly. At the same time, materials such as 3-4 mm cardboard should be placed between the support bricks and the crucible as a pre expansion space for the crucible;

(3) The crucible for installing the resistance furnace should be placed in the center of the resistance furnace. The bottom of the crucible should be higher than the bottom row of heating elements, and insulation cotton should be used to seal the top and between the crucibles.

(4) Install a crucible for the induction furnace to ensure that it is placed in the center of the induction coil to prevent local overheating and cracking of the crucible.

Preheating/Using the crucible correctly for the first time can greatly prolong its service life.

(1) According to different types of crucible furnaces, when using the crucible for the first time without adding materials, preheat the crucible to around 200 ℃ for 60-120 minutes and dry it for 60 minutes. The purpose is to evaporate the moisture absorbed on the surface of the crucible. Prevent bursting during initial use.

(2) After preheating, the crucible should be heated to 800 ℃ (about 2 hours) as soon as possible, and kept warm for 20-30 minutes before being raised or lowered to the working temperature. The purpose is to quickly pass through the temperature range that is prone to oxidation in graphite crucibles.

(3) The crucible usually does not need to be preheated again after the first preheating, unless the crucible is dampened again. Attention should be paid to new crucibles and crucibles that have been cooled for a long time. Silicon carbide graphite crucibles are prone to thermal stress impact if not preheated properly.

For large capacity furnaces and/or furnaces with high output burners, the following crucible preheating procedures must be followed to avoid damage to the crucible due to thermal shock;

(1) Slowly heat the empty crucible at a heating rate of 200 ℃ for 2 hours to remove moisture;

(2) Heat the crucible at a rate of 2 hours to 600 ℃;

(3) Heat the crucible to 800 ℃ at the normal heating rate. The crucible used for aluminum insulation must be maintained at 800 ℃ for about 30 to 40 minutes to allow the glaze layer on the surface of the crucible to fully exert its function.

(4) After the above steps, the crucible can be safely put into normal use, and it is also necessary to pay attention to following the crucible safety operating procedures during use

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