Synthesis and Properties of Al2O3-Fe2O3 Ceramic Composite with Limited Electrical Conductivity

Ceramic materials with a density of more than 95 % of theoretical containing 1-30 mass % of iron oxide were synthesized in the Al2O3-Fe2O3 system. During ceramics air sintering, the material with Fe2O3 content below 10 % is monophase and comprises alpha-Al2O3-based solid solution. With Fe2O3 concentration above 10%, an iron oxide-based solution is generated in significant amounts. As soon as the material becomes two-phase, the value of its electrical conductivity increases by three orders of magnitude and reaches 10(-8)-10(-9) Sm/m. Iron oxide is reduced to metal when trying to increase material density by vacuum sintering or hot isostatic pressing. Furthermore, a composite representing uniformly distributed spherical metallic iron particles in the alpha-Al2O3 matrix is generated.