MgO: refractory material

      When one looks for a commercially viable refractory oxide, MgO (magnesia) is high on the list: it has a very high melting point (3073 K), can withstand heating above 2300K for long periods, and is relatively inexpensive. Magnesia is fabricated into bricks for lining furnaces in steelmaking. Incorporating chromium ore into the refractory bricks increases their resistance to thermal shock. Magnesia bricks are also widely used in night-storage radiators: MgO conducts heat extremely well, but also has the ability to store it. In a radiator, the bricks absorb heat which is generated by electrically heated filaments during periods of ‘off-peak’ consumer rates, and then radiate the thermal energy over relatively long periods.