High thermal conductivity ceramic body

Abstract

A process for producing an aluminum nitride ceramic body having a composition defined and encompassed by polygon ABCDEFGH excluding line DE of FIG. 2, a porosity of less than about 10% by volume, and a thermal conductivity greater than 0.70 W/cm.multidot.K at 25.degree. C. which comprises forming a mixture comprised of aluminum nitride powder containing oxygen, an Ln oxide selected from the group consisting essentially of erbium oxide, holmium oxide, a mixture and solid solution thereof, and free carbon, shaping said mixture into a compact, said mixture and compact having a composition wherein the equivalent % of Ln and aluminum ranges from point A up to point E of FIG. 2, said mixture and said compact having an equivalent % composition of Ln, Al, O and N outside the composition defined and encompassed by polygon ABCDEFGH of FIG. 2, heating said compact up to a temperature at which its pores remain open reacting said free carbon with oxygen contained in said aluminum nitride producing a deoxidized compact, said deoxidized compact having a composition wherein the equivalent % of Al, Ln, O and N is defined and encompassed by polygon ABCDEFGH excluding line DE of FIG. 2, and sintering said deoxidized compact producing said ceramic body.