Patent ID: 8226865

Claim:
A method for manufacturing an aluminum-nitride-based composite material, comprising a step of hot-press sintering of a mixture containing aluminum nitride at a content ratio in the range of 49.8 to 69.4 vol %; magnesium oxide at a content ratio in the range of 20.2 to 40.0 vol %; and a rare earth metal oxide at a content ratio in the range of 0.5 to 30.0 vol % and/or at least one selected from the group consisting of a rare earth metal fluoride, an alkali earth metal fluoride, calcium oxide, and aluminum fluoride at a content ratio in the range of 0.5 to 5.7 vol %; with the content ratios of transition metals, excluding rare earth metals, alkali metals, and boron, respectively as low as 1000 ppm or lower.