When it comes to ceramic firing, the choice of tray material is not a trivial matter. Incorrect selection of ceramic trays often leads to issues such as mosaic collapse and sanitary ware deformation. The quality of the tray material directly affects the outcome of high - temperature ceramic firing.
Let's take a look at how different ceramic categories have specific requirements for tray performance.
Mosaic: Mosaics require trays with high flatness and good thermal stability. During the firing process at around 1000°C - 1200°C, any slight deformation of the tray can cause the mosaic to collapse. For example, if the tray has poor thermal stability, it may expand unevenly during heating, leading to the displacement of mosaic pieces.
Sanitary Ware: Sanitary ware, which is usually fired at 1200°C - 1300°C, needs trays with excellent anti - thermal shock properties. Since sanitary ware has a relatively large size and complex shape, the tray must be able to withstand rapid temperature changes without cracking or deforming. Otherwise, the sanitary ware may warp or crack during firing.
Roof Tiles: Roof tiles are fired at a relatively high temperature, around 1300°C - 1400°C. They require trays with high wear resistance and chemical inertness. The trays need to resist the abrasion caused by the movement of roof tiles during the firing process and should not react chemically with the roof tile materials.
Let's compare the key indicators of traditional refractory bricks and composite corundum - mullite trays. In terms of thermal expansion coefficient, traditional refractory bricks usually have a relatively high thermal expansion coefficient. For example, the thermal expansion coefficient of some traditional refractory bricks can reach 0.8% - 1.2% at 1000°C - 1400°C. In contrast, the composite corundum - mullite tray has a lower thermal expansion coefficient, typically around 0.3% - 0.6% in the same temperature range, which means it can better maintain its shape during heating and cooling.
Regarding the flexural strength, the composite corundum - mullite tray also shows better performance. Traditional refractory bricks may have a flexural strength of around 20 - 30 MPa, while the composite corundum - mullite tray can reach 40 - 60 MPa, providing better support for ceramic products during firing.
| Indicator | Traditional Refractory Bricks | Composite Corundum - Mullite Trays |
|---|---|---|
| Thermal Expansion Coefficient (1000°C - 1400°C) | 0.8% - 1.2% | 0.3% - 0.6% |
| Flexural Strength (MPa) | 20 - 30 | 40 - 60 |
In different temperature zones of the kiln, the trays face different risks. In the low - temperature zone (1000°C - 1200°C), the main risk is the slow oxidation of the tray surface, which may reduce its anti - wear performance. In the medium - temperature zone (1200°C - 1300°C), the trays need to resist thermal shock, and any sudden temperature change may cause cracks. In the high - temperature zone (1300°C - 1400°C), the trays are prone to deformation due to high - temperature stress.
To manage the tray cycle, regular inspection is essential. For example, you can use non - destructive testing methods to detect internal cracks in the trays. Also, learn to identify signs of aging, such as surface discoloration or a decrease in anti - wear performance. When the trays show signs of severe aging, they should be replaced in time to ensure the quality of ceramic firing.
One of our customers was facing the problem of tray warping during continuous firing. After analyzing their process, we found that the root cause was the uneven heating of the trays. We suggested adjusting the kiln heating system to ensure more uniform heat distribution. At the same time, we recommended using composite corundum - mullite trays with better thermal stability. After implementing these solutions, the customer's firing yield increased significantly, and the problem of tray warping was effectively solved.
Industry Common Problem: Many ceramic manufacturers struggle with the problem of poor firing quality due to improper tray selection. This not only affects the production efficiency but also increases the production cost.
To help you make more scientific decisions on ceramic tray selection, we have prepared a valuable 《Ceramic Tray Selection White Paper》. It contains more in - depth analysis, detailed data, and practical selection suggestions. You can also join our technical exchange group to communicate with industry experts and other ceramic manufacturers, sharing experiences and solving problems together.
