High thermal conductivity aluminum nitride ceramic body

Abstract

A process for producing a polycrystalline aluminum nitride ceramic body having a composition defined and encompassed by line ABCDEFA but not including lines CD and EF of FIG. 1, a porosity of less than about 10% by volume of said body and a thermal conductivity greater than 1.0 W/cm.multidot.K at 22.degree. C. which comprises forming a mixture comprised of aluminum nitride powder and an yttrium additive selected from the group consisting of yttrium, yttrium hydride, yttrium nitride and mixtures thereof, said aluminum nitride and yttrium additive having a predetermined oxygen content, said mixture having a composition wherein the equivalent % of yttrium, aluminum, nitrogen and oxygen is defined and encompassed by line ABCDEFA but not including lines CD and EF in FIG. 1, shaping said mixture into a compact and sintering said compact at a temperature ranging from about 1850.degree. C. to about 2170.degree. C. in an atmosphere selected from the group consisting of nitrogen, argon, hydrogen and mixtures thereof to produce said polycrystalline body.