Fused zirconia corundum brick in the production and use of the process will appear the following three kinds of cracks:

1. Stress cracks:

Fused zirconia corundum brick composition of zirconia has the largest proportion of zirconium oxide, there is a segregation in the casting process, the annealing process is difficult to release the stress uniformity, and cracks occur. (JC493 standard for such cracks have specific provisions).

2. Phase change cracks:

Fused zirconia corundum bricks in the kiln ignition baking kiln during the heating in 1150 ° C or so, cooling to 1000 ° C near the existence of oblique zirconia monoclinic and tetragonal irreversible phase change brought about by the volume effect, resulting in anomalous contraction or expansion, if the baking kiln in the vicinity of the temperature of the phase change in the control is not appropriate, it is prone to cracking (transverse and longitudinal cracks, mostly longitudinal cracking is dominant). In order to avoid phase change cracks in the kiln when the precautions, will be discussed in detail in the subsequent pages.

3. Crystalline phase change cracks:

Kiln operation, fused zirconia corundum brick long-term contact with the glass liquid, the internal glass phase of the brick body will slowly undergo a crystalline phase transition, resulting in mullite and a small amount of quartz, but due to the slow change in the crystalline phase, the volume change is not large, generally not easy to crack, even if there is a fine cracks, does not affect the use of bricks.