Industry News
High-Alumina Brick vs. Mullite Brick: What's the Difference?
Comparing high-alumina and mullite bricks by crystalline phase, composition and refractoriness under load.
High-alumina bricks and mullite bricks are both common refractories, but they differ as follows:
Different crystalline phases: The main component of high-alumina brick is alumina (Al2O3), typically 48%–80%, whereas the main crystalline phase of mullite brick is mullite, with an alumina content of about 67%–70% or more.
Mullite brick consists mainly of mullite and aluminum oxide, offering good high-temperature stability and refractoriness; its refractoriness under load (onset temperature) is above 1650°C, higher than that of high-alumina brick.
High-alumina brick consists mainly of alumina with small amounts of silicates. It usually has higher cold crushing strength and good corrosion resistance, but its refractoriness under load is generally around 1400°C, lower than that of mullite brick.
Therefore, where higher refractoriness is required in high-temperature service, mullite brick is usually more suitable than high-alumina brick.