Teach you how to improve the temperature resistance of the intermediate frequency furnace lining

Luoyang Quantong Kiln Industry Co., Ltd. teaches you how to improve the temperature resistance of the intermediate frequency furnace lining

1. Remove the mica paper when building the furnace.

2. Treat the crystal quartz sand for furnace construction.

3. Hand selection: mainly remove lumps and other impurities.

4. Magnetic separation: Magnetic impurities must be completely removed.

5. Dry ramming material: It must be dried slowly, the drying temperature is 200 degrees Celsius - 300 degrees Celsius, and the temperature is kept for more than 4 hours.

6. Selection of binder for medium frequency electric furnace: use boric anhydride (B2O3) instead of boric acid (H3BO3) as binder, and the addition amount is 1.1%-1.5%.

7. Selection and ratio of furnace building materials.

8. Selection of furnace building materials: It should be noted that not all quartz sands with SiO2 greater than or equal to 99% can be used as lining materials for induction furnaces. The important thing is the size of the quartz grains. , (such as crystal quartz sand SiO2 with high purity, white and transparent appearance.) The larger the furnace capacity, the higher the requirements for crystal grains.

9. Proportion: The ratio of quartz sand for furnace lining: 6-8 mesh, 10 percent-15 percent, 10-20 mesh, 25 percent-30 percent, 20-40 mesh, 25 percent-30 percent, 270 mesh, 25 percent-30 percent.

10. Knotting of the furnace lining: The quality of the furnace lining is directly related to the quality of sintering. The sand particle size distribution is uniform and will not cause segregation during knotting. It is beneficial to improve the service life of the induction furnace lining.

11. Knotted furnace bottom: the thickness of the furnace bottom is about 280mm, and the sand is filled in 4 times. During manual knotting, the density is not uniform everywhere, and the furnace lining after baking and sintering is not dense. Therefore, the thickness of the feeding must be strictly controlled. The thickness of sand is not more than 100mm\/time, the furnace wall is controlled within 60mm, multiple people are divided into shifts, 4-6 people per shift, each time the knot is 30 minutes to change, rotate slowly around the furnace, and use even force to avoid causing Uneven density.

12. Knot the furnace wall: the thickness of the furnace lining is 110-120mm, add dry knotting material in batches, the cloth is uniform, the thickness of the filler is not more than 60 mm, and the knot is knotted for 15 minutes (manual knotting) until it is level with the upper edge of the induction coil Qi. The crucible mold is not taken out after the knot is finished, and the induction heating function is used during drying and sintering.

13. Baking and sintering specifications for neutral furnace lining material manufacturers: In order to obtain the 3-layer structure of the furnace lining, the baking and sintering process is roughly divided into three stages:

(1) Baking stage: The crucible mold is heated to 600 degrees Celsius at a speed of 25 degrees Celsius\/h and 50 degrees Celsius\/h respectively, and kept for 4 hours, in order to completely remove the moisture in the furnace lining.

(2), semi-sintering stage: heat up to 900 degrees Celsius at 50 degrees Celsius\/h, hold for 3 hours, heat up to 1200 degrees Celsius at 100 degrees Celsius\/h, and hold for 3 hours. The heating rate must be controlled to prevent cracks.

(3) Complete sintering stage: During high temperature sintering, the sintering structure of the intermediate frequency electric furnace crucible is the basis for improving its service life. The sintering temperature is different, the thickness of the sintered layer is insufficient, and the service life is significantly reduced.