Stabilized zirconia bodies of improved toughness

Claim 1

A ceramic body exhibiting a modulus of rupture in excess of 50,000 psi and a toughness greater than 5 MPaγm consisting essentially of ZrO 2 partially stabilized through the presence of 0.5-10% by weight Y 2 O 3 as the primary stabilizing oxide and 1-10% by weight total of at least one secondary stabilizing oxide selected from the group of MgO, CaO, CuO, ZnO, and CeO 2 , said body consisting essentially of about 50-70% by volume cubic ZrO 2 , greater than 20% and up to 50% by volume tetragonal ZrO 2 present as islands within the cubic ZrO 2 grains and having dimensions of about 0.25-0.75 micron, and less than 10% by volume monoclinic ZrO 2 present along the grain boundaries and having dimensions of about 1-10 microns.

Claim 6

A method for making a ceramic body exhibiting a modulus of rupture in excess of 50,000 psi and a toughness greater than 5 MPaγm consisting of ZrO 2 partially stabilized through the presence of Y 2 O 3 as the primary stabilizing oxide and at least one secondary stabilizing oxide selected from the group of MgO, CaO, CuO, ZnO, and CeO 2 which comprises the steps of: (a) preparing a batch consisting essentially, in weight percent on the oxide basis, of 0.5-10% Y 2 O 3 , 1-10% total of at least one member of the group of MgO, CaO, CuO, ZnO, and CeO 2 , and the remainder ZrO 2 ; (b) shaping said batch into a body of a predetermined configuration; (c) firing said body at a temperature between about 1600°-1800° C. for a period of time sufficient to produce an integral sintered body; (d) cooling said sintered body at a rate in excess of 100° C./hour to a temperature between about 1000°-1475° C.; (e) holding said body within that range of temperatures for a period of time sufficient to induce the precipitation of tetragonal ZrO 2 as islands within cubic ZrO 2 grains and having dimensions of about 0.25-0.75 microns, thereby producing a body consisting essentially of about 50-70% by volume cubic ZrO 2 , greater than 20% and up to 50% by volume tetragonal ZrO 2 , and less than 10% by volume monoclinic ZrO 2 present along the grain boundaries and having dimensions of about 1-10 microns; and then (f) cooling said body to room temperature.

Claim 7

A method for making a ceramic body exhibiting a modulus of rupture in excess of 50,000 psi and a toughness greater than 5 MPaγm consisting of ZrO 2 partially stabilized through the presence of Y 2 O 3 as the primary stabilizing oxide and at least one secondary stabilizing oxide selected from the group of MgO, CaO, CuO, ZnO, and CeO 2 which comprises the steps of: (a) preparing a batch consisting essentially, in weight percent on the oxide basis, of 0.5-10% Y 2 O 3 , 1-10% total of at least one member of the group of MgO, CaO, CuO, ZnO, and CeO 2 , and the remainder ZrO 2 ; (b) shaping said batch into a body of a predetermined configuration; (c) firing said body at a temperature between about 1600°-1800° C. for a period of time sufficient to produce an integral sintered body; (d) cooling said sintered body at a rate in excess of 100° C./hour to a temperature between about 1000°-1475° C.; (e) holding said body within that range of temperatures for a period of time sufficient to induce the precipitation of tetragonal ZrO 2 as islands within cubic ZrO 2 grains and having dimensions of about 0.25-0.75 microns, thereby producing a body consisting essentially of about 50-70% by volume cubic ZrO 2 , greater than 20% and up to 50% by volume tetragonal ZrO 2 , and less than 10% by volume monoclinic ZrO 2 present along the grain boundaries and having dimensions of about 1-10 microns; and then (f) cooling said body to room temperature.