Patent ID: 7223356

Claim:
A method for preparing a thin ceramic material with a controlled surface porosity gradient, comprising: a) a step (P) of preparing the porous pore-forming substrate of a controlled thickness; b) a step (Q) of preparing a ceramic suspension in a solvent; c) a step (A) of infiltrating said porous pore-forming substrate of a controlled thickness with said suspension of a ceramic material; d) a step (B) of evaporating said solvent, in order to form a pore former/solid ceramic composite structure (S); e) a step (B′) of cutting said composite structure (S) into structure elements (S); f) a step (E) of forming an assembly from the two elements (s 1 ) and (s 2 ) obtained in step (B′), wherein said elements are stacked back to back with their dense faces being adiacent; g) a step of thermocompression; h) a step (C) of debinding; and i) a step (D) of sintering, wherein a constituent ceramic material of the ceramic suspension is chosen from oxides of formula (I): oxides of formula (I): (M a O b ) 1−x (R c O d ) x (I) in which M represents at least one trivalent or tetravalent atom chosen mainly from bismuth (Bi), cerium (Ce), zirconium (Zr), thorium (Th), gallium (Ga) or hafnium (Hf), a and b are such that the M a O b structure is electrically neutral, R represents at least one divalent or trivalent atom chosen mainly from magnesium (Mg), calcium (Ca) or barium (Ba), strontium (Sr), gadolinium (Gd), scandium (Sc), ytterbium (Yb), yttrium (Y), samarium (Sm), erbium (Er), indium (In), niobium (Nb) or lanthanum (La), c and d are such that the R c O d structure is electrically neutral and x is between about 0.05 and about 0.30.