Neutral lining material manufacturers teach you how to improve the temperature resistance of intermediate frequency furnace lining

1. Remove mica paper when building the furnace.

2, the furnace with crystal quartz sand treatment.

3, hand selection: the main removal of lumps and other impurities.

4, magnetic separation: must completely remove magnetic impurities.

5, dry ramming materials: must be slow drying treatment, drying temperature of 200℃-300℃, heat preservation for more than 4 hours.

6, the selection of medium frequency electric furnace binder: with boron anhydride (B2O3) instead of boric acid (H3BO3) as the binder, the amount of addition is 1.1%-1.5%.

7. Selection and ratio of furnace building materials.

8, the selection of furnace materials: It should be noted that not all SiO2≥99% quartz sand can be used as induction furnace lining materials, the important thing is the quartz grain size, the larger the grain, the less lattice defects, the better (such as crystal quartz sand SiO2 high purity, white appearance, transparent). The larger the furnace capacity, the higher the grain requirements.

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

10, lining knot: lining knot quality is directly related to the quality of sintering. When knotting, the sand particle size distribution is uniform without segregation, the sand layer after knotting has high density, and the probability of cracking after sintering is reduced, which is conducive to improving the service life of induction furnace lining.

11, tying the bottom of the furnace: the thickness of the furnace is about 280mm, and it is filled with sand four times. When manually tying, the density is not uneven everywhere, and the lining is not dense after baking and sintering. Therefore, it is necessary to strictly control the feeding thickness, the general sand filling thickness is not more than 100mm/ time, the furnace wall is controlled within 60mm, many people are in shift operation, 4-6 people per shift, each time the knot is tied for 30 minutes, the rotation around the furnace is slow, the force is uniform, so as not to cause uneven density.

12, Tie the furnace wall: the thickness of the furnace lining is 110-120mm, add the dry knotting material in batches, the cloth is uniform, the thickness of the filler is not more than 60mm, tie for 15 minutes (manual knotting), until it is flush with the upper edge of the induction ring. When the crucible die is not taken out after tying, it plays induction heating role during drying and sintering.

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

(1), baking stage: the crucible mold is heated to 600℃ at the speed of 25℃/h and 50℃/h respectively, and the heat preservation is 4h, the purpose is to completely eliminate the water in the furnace lining.

(2), semi-sintering stage: temperature rise to 900℃ at 50℃/h, heat preservation for 3h, temperature rise to 1200℃ at 100℃/h, heat preservation for 3h, the temperature rise rate must be controlled to prevent cracks.

(3) Full sintering stage: when sintering at high temperature, the sintering structure of the medium frequency electric furnace crucible is the basis for improving its service life. With different sintering temperature and insufficient sintering layer thickness, the service life is obviously reduced.