When working with high temperatures and high temperature ceramic insulation, it is important to remember that refractories expand and contract when exposed to high heat or when they cool. When you are designing the refractory materials for your project, it is important to know the behaviors of thermal expansion in the materials you are utilizing. If the materials’ thermal expansion is more than the furnace structure it is lining, then it may get destroyed or broken. It is important to overestimate and design your linings with this overexpansion in mind. However, while allowing for expansion room, it is also important to remember not to allow for too much room because this will cause lining instability.
You also want to understand the thermal expansion because it will be used for assessing the thermal shock resistance of the materials. The thermal shock of materials occurs when the severe temperatures cause damage or stress inside your furnace or materials.
You can measure the linear thermal expansion of your refractory materials by determining the change in length and size of the bar-shaped specimen when it is heated at a constant rate. You can also use an electrical transducer and attaching it to the dilatometer, which is located on top of the furnace.
When considering your refractory materials, you should also keep in mind the idea of reversible thermal expansion. When your refractory materials cool, they typically return to their original dimensions.
To learn more about high temperature ceramic insulation, please refer often to our blog!