Aluminum Nitride, a Refractory for Aluminum to 2000°C.

In commercial practice, where temperatures are low, a number of commercially available materials are satisfactory as a container for molten aluminum. None of these, however, resists attack by aluminum in the temperature range 1800° to 2000°C. An investigation was conducted to find a material completely inert to aluminum at these high temperatures. Aluminum nitride emerged as the material that was inert to aluminum and showed satisfactory properties as a ceramic material. A method of preparing high‐purity AIN by striking a d.‐c. arc between two high‐purity aluminum electrodes in a nitrogen atmosphere is described. A refractory having excellent strength and low porosity was achieved by hydrostatic pressing and firing at high temperatures. The mechanical, electrical, thermal, and chemical properties of the refractory are discussed.