Casting fused zirconia corundum bricks appear pinhole

Casting fused zirconia corundum bricks appear pinhole as following reasons:
(1)  String to move the electrode before casting fused zirconia corundum bricks, so that a large number of graphite powder down into the furnace, resulting in the fused brick entrapment of pores and not dense;
(2) electroless casting AZS fused bricks, in the electrode with the molten solution continues to react in the case of liquid is not dense, it is clear that the fused brick will not be dense;
(3) with raw material casting, especially when the furnace area before the raw material when casting fused zirconia corundum brick, the raw material into the casting, in addition to the destruction of lithofacies structure, but also appear pores.
Fused zirconia corundum brick appear pinholes tend to occur in the casting of the first piece of fused bricks, this is because the mouth area is not clean, mixed with raw materials or graphite mouth oxide outcrop powder, and the rapid reaction of the melt after pouring Into the mold, due to melt viscosity, these bubbles can not float, then irregularly stay in the melt. So casting fused zirconia corundum brick to keep the melt channel cleaning can not be ignored. Other conditions lead to fused zirconia corundum brick stomata is the most common is the charge of moisture and melting temperature is insufficient, so that fused bricks become shrinkage dispersion type or bread type.