Electrophoretic Method for the Production of Ceramic Structures

Abstract

The invention relates to a method for producing ceramic structures and gradient structures whose particle size distribution has at least partly smaller values than the particle size distribution of the suspension from which the same are produced. According to the inventive method, a suspension containing ceramic particles is provided between a couple of electrodes, whereupon an electric field is applied to the couple of electrodes while the electrode surfaces of the couple of electrodes are placed perpendicular to a component of a gravitational field such that a fraction of the particles is deposited on the electrode of the couple of electrodes, which is located upstream of the component of the gravitational field, in the form of a ceramic structure.

1 . A method for producing ceramic structures by applying an electric field between the electrodes of respectively one electrode pair, submerged in a suspension that is positioned in a gravitational field and contains ceramic particles in a distribution of particle sizes, such that on one of the electrodes of the respective electrode pair only the particle size fraction of the ceramic particles is deposited, which is smaller than a critical particle size that results from the balance between the forces of the electrical field and the forces of the gravitational field.  
   
   
       2 . The method for producing ceramic structures as defined in  claim 1 , characterized in that the electrodes of the respective electrode pair are arranged parallel to each other and horizontal in the gravitational field of the earth and that the ceramic structure is deposited on the upper electrode.  
   
   
       3 . The method for producing ceramic structures as defined in  claim 1 , characterized in that the gravitational field is generated with the aid of a rotating centrifuge.  
   
   
       4 . The method for producing ceramic structures as defined in  claim 3 , characterized in that the electrodes of the respective electrode pair are arranged parallel to each other and perpendicular to the direction of the gravitational field, generated by a rotating centrifuge, and that the ceramic structure is deposited on the inner electrode.  
   
   
       5 . The method for producing ceramic structures as defined in one of the claims  1 , characterized in that the electrical field and the gravitational field can be varied independent of each other with respect to intensity and time.  
   
   
       6 . The method for producing ceramic structures as defined in one of the claims  1 , characterized smaller values for the distribution of particle sizes in the ceramic structure than the distribution of particle sizes in the suspension.  
   
   
       7 . The method for producing ceramic structures as defined in claims  1 , characterized in that the ceramic particles comprise: 
 structural ceramics such as Al 2 O 3 , ZrO 2 , mullite, SiC, Si 3 N 4  and/or    functional ceramics such as BaTiO 3  or lead-zirconate-titanate (PZT) and/or    bio-ceramics such as hydroxyl apatite (Ca(OH) (PO 4 ) 3 ) and/or    mineral glass.    
   
   
       8 . The method for producing ceramic structures as defined in claims  1 , characterized in that the suspension contains at least two different types of ceramic particles.  
   
   
       9 . The method for producing ceramic structures as defined in claims  1 , characterized in that the ceramic particle sizes range from 5 nm to 500 μm, preferably from 10 nm to 100 μm, and especially preferred from 10 nm to 10 μm.  
   
   
       10 . A ceramic structure produced in accordance with claims  1 .  
   
   
       11 . A ceramic gradient structure produced in accordance with claims  5 .