Body made of a ceramic material

Abstract

A body made of a ceramic material stabilized by a stabilizing agent and a process for preparing the body. The body includes a surface region extending from the surface of the body to a predetermined depth. The stabilizing agent is enriched in the surface region. The proportion of the stabilizing agent in the surface region continuously increases from the predetermined depth to the surface. The process includes applying the stabilizing agent to the surface of a basic body made of a ceramic material and heating the basic body with the stabilizing agent applied thereon at a temperature such that at least a portion of the stabilizing agent diffuses into the ceramic material.

1 . A body made of a ceramic material stabilized by a stabilizing agent, the body comprising a surface region extending from a surface of the body to a predetermined depth, the stabilizing agent being enriched in the surface region, wherein a proportion of the stabilizing agent in the surface region continuously increases from the predetermined depth to the surface. 
     
     
         2 . The body according to  claim 1 , wherein the proportion of stabilizing agent of the ceramic material in the surface region is higher than in the remainder of the body. 
     
     
         3 . The body according to  claim 1 , wherein the stabilizing agent is selected from the group consisting of yttrium, cerium, and their respective oxides. 
     
     
         4 . The body according to  claim 1 , wherein the surface region extends from the surface of the body to a depth of at least 20 nm. 
     
     
         5 . The body according to  claim 4 , wherein the surface region extends from the surface of the body to a depth of at least 50 nm. 
     
     
         6 . The body according to  claim 5 , wherein the surface region extends from the surface of the body to a depth of at least 100 nm. 
     
     
         7 . The body according to  claim 1 , wherein at least a part of the surface of the body has a surface roughness. 
     
     
         8 . The body according to  claim 1 , wherein the body is made of a ceramic material comprising zirconia. 
     
     
         9 . The body according to  claim 8 , wherein the zirconia is yttria-stabilized. 
     
     
         10 . The body according to  claim 1 , wherein a crystal structure of the ceramic material in the surface region is such that the proportion of monoclinic phase is at most as high as in the remainder of the body. 
     
     
         11 . The body according to  claim 10 , wherein the crystal structure of the ceramic material in the surface region is such that the proportion of monoclinic phase is less than 20%. 
     
     
         12 . A process for preparing the body according to  claim 1 , the process comprising applying a stabilizing agent to a surface of a basic body made of a ceramic material and heating the basic body with the stabilizing agent applied thereon at a temperature such that at least a portion of the stabilizing agent diffuses into the ceramic material. 
     
     
         13 . The process according to  claim 12 , further comprising roughening at least a part of the surface of the basic body by a subtractive treatment before applying the stabilizing agent. 
     
     
         14 . The process according to  claim 13 , wherein the subtractive treatment comprises an etching step. 
     
     
         15 . The process according  claim 14 , wherein the subtractive treatment further comprises a sand-blasting step prior to the etching step. 
     
     
         16 . The process according to  claim 12 , wherein the stabilizing agent is applied to the surface of the basic body by a sol-gel process. 
     
     
         17 . The process according to  claim 16 , wherein the stabilizing agent is applied to the surface of the basic body by a dip-coating process, by chemical vapour deposition, by physical vapour deposition, and/or by ion implantation. 
     
     
         18 . A body obtainable by the process according to  claim 12 .