Why are chromite-magnesia bricks more resistant to spalling than pure chromite bricks?

The premise that chromite-magnesia bricks are more resistant to spalling than pure chromite bricks is accurate. While pure chromite bricks were historically used for their high melting point and neutral chemical behavior, they have been largely replaced by mixtures of chromite and magnesia.1

The addition of magnesia to chromite ore improves the material's performance by enhancing its volume stability and overall refractoriness. By creating a composite structure, these bricks better withstand the mechanical and thermal stresses that lead to spalling—the cracking or flaking of refractory material—compared to bricks composed of 100 percent chromium ore. These basic refractories are particularly valued for their durability in high-temperature industrial environments, such as electric furnaces and steelmaking applications, where they exhibit excellent resistance to iron oxides and basic slags.12