Whether aluminium oxide can conduct heat depends on the crystalline phase of the material. It is also dependent on the electrolyte used during anodization. The thermal conductivity of AAOs is highest in the range of temperatures 1300 degC, and lowest in the range of 100 degC.
The most common crystalline form of aluminium oxide is corundum. It has a high hardness and good dielectric properties. This makes it suitable for use in structural applications. But different kinds of corundum are available and have different colors due to trace impurities.
Aluminum oxide is commonly called alpha alumina in the materials science community. It is a highly-efficient ceramic material with very high resistance to wear. It has a wide range of applications, including as abrasive, filler, and catalyst support for many industrial reactions. The chemical formula is Al2O3. It can be found in two basic formulations, with a pH of 9.5 in water or acidic.
In addition to its crystalline form, aluminium oxide can exist in several non-crystalline phases. The most stable phase is the hexagonal alpha phase. However, it can transition to other crystalline phases, such as the d/g-phase and oxalic-phase. This is characterized by an increase in specific heat from 0.74 kJ kg-1 K-1 at 45 degC to 0.85 kJ kg-1 K-1 at 1300 degC.
To understand the variations in thermal conductivity of annealed aluminium alloy, the structural behavior of different crystalline phases has been studied. Specifically, the d/g-phase of AAOs has the highest thermal conductivity at high temperatures. The a-Al2O3 phase has lower thermal conductivity.