[China Aluminum Network] The black and white spots often seen on high-alumina bricks are primarily caused by the high-temperature environment and a reducing atmosphere within the kiln. Under such conditions, iron and titanium ions can be reduced, leading to color changes. At lower temperatures, these ions may become oxidized again, resulting in a mixed appearance of black and white areas. Crown Electronics CO., LTD , https://www.crownhaero.com
Another contributing factor is the placement of the high-alumina brick near the firebox, where it is exposed to intense heat. This can lead to an oxygen-rich environment, which prevents the formation of a reducing atmosphere. Additionally, during the cooling phase, if the process is too slow, low-cost iron and titanium ions may reoxidize, further affecting the color uniformity.
These issues highlight the importance of careful control during the manufacturing process by refractory material producers. Proper temperature management, atmosphere regulation, and controlled cooling are essential to ensure the final product has a consistent and aesthetically pleasing appearance. Understanding and addressing these factors not only improves the visual quality but also enhances the performance and durability of the high-alumina bricks in industrial applications.