First, the advantages of spray coating and coating materials for tundish are as follows:

1) high refractoriness and good corrosion resistance to molten steel and slag.

2) Good construction performance and baking adaptability, easy to smear, in the baking and use process does not separate from the permanent layer, has good integrity and adhesion, not cracking, not peeling;

3) the thermal conductivity of the coating is small, which meets the requirements of tundish insulation.

4) It does not pollute the molten steel, and can absorb the impurities in molten steel and improve the quality of steel when using Mg-Ca coating.

5) compared with the heat insulation board, the service life of the paint is longer, which is conducive to the improvement of the factory labor productivity.

6) with the solidification of remaining molten steel, the residual lining of the coating is disintegrated and separated from the permanent layer after pouring.

Two. The defects of tundish spray coating and coating are as follows:

1) The tundish spraying coating is affected by the environment greatly, and the water content of the working layer is difficult to be removed during the winter construction, so it is easy to freeze.

2) The coating layer of tundish has larger porosity and is easy to form thicker coating layer, which enhances the corrosion of slag to coating and reduces the effective volume of tundish.

3) The expansion coefficient and physical properties of molten slag are different from those of brucite in the working layer. When the temperature fluctuates, due to the effect of thermal stress in the coating, the structure of the coating layer cracks and peels off, resulting in structural damage to the working layer, and thus resulting in liquid steel. Pollution;

4) The addition of water during construction will cause hydration of MgO and CaO, and wrinkles and cracks will appear on the surface of the coating during baking.

5) In order to ensure that the coating and permanent layer bond firmly, spray coating and coating baking time is longer, otherwise there will be coating spalling and cracking;

6) The water evaporated from the coating has water corrosion effect on the castable of permanent layer and reduces the service life of the permanent layer.

7) the decomposition of undischarged bound water at baking temperature causes oxidation and hydrogen absorption of molten steel.

8) longer sintering time will result in serious sintering phenomenon and can not be automatically removed.