Metal oxide ceramic material, precursors, preparation and use thereof

A pre-ceramic body P2z of zirconium oxide having:

• a mean grain size of less than 45 nm,
• a density of between 52% and 68%, relative to the theoretical density in the absence of pores,
• a hardness of more than 150 HV,
• a mechanical biaxial bending strength of at least 25 MPa, and
• a mean pore size of between 2 nm and 15 nm.

A method for the preparation of a ceramic body P3, comprising the following steps:

• (a1) providing a dispersion of crystalline metal oxide particles having a mean size of 40 nm or less;
• (b1) introducing the dispersion into a mould and forming a wet body by pressure filtering the dispersion into the mould;
• (b1′) optionally, pressing the wet body, by pressure filtration;
• (b2) demoulding the wet body under conditions of relative humidity of more than 80%;
• (b3) optionally, when the wet body has a density gradient, removing the part of the wet body at the end of filtration;
• (c1) forming a green body P1 by drying the wet body under conditions of relative humidity higher than 90%;
• (c1′) optionally, shaping the green body P1;
• (d1) optionally, unbinding the green body P1;
• (e1) optionally, forming a pre-ceramic body P2 by pre-sintering green body P1 of one of steps (c1), (c1′) or (d1), at a temperature between 400° C. and 800° C.;
• (e2) optionally, shaping pre-ceramic body P2;
• and
• (f1) forming a ceramic body P3 by sintering green body P1 of one of steps (c1), (c1′) or (d1) or by sintering pre-ceramic body P2 of step (e1) or (e2), sintering being performed at a temperature of between 900° C. and 1300° C.

A method for the preparation of a green body, comprising the following steps:

• (a1) providing a dispersion of crystalline metal oxide particles having a mean size of 40 nm or less;
• (b1) introducing the dispersion into a mould and forming a wet body by pressure filtering the dispersion into the mould;
• (b1′) optionally, pressing the wet body by pressure filtration;
• (b2) unmoulding the wet body under conditions of relative humidity of more than 80%;
• (b3) optionally, when the wet body has a density gradient, removing the part of the wet body at the end of filtration;
• (c1) forming a green body P1 by drying the wet body under conditions of relative humidity higher than 90%, and
• (c1′) optionally, shaping the green body P1.

A ceramic body P3z of crystalline zirconium oxide having:

• a mean grain size of less than 200 nm,
• a density of more than 99%,
• a mechanical biaxial bending strength of at least 600 MPa, and
• a mean pore size of less than or equal to 20 nm.