Method for producing an open-pore molded body which is made of a metal, and a molded body produced using said method

Abstract

A method for producing open-pored molded bodies made of a metal. The surface of the metal open-pored molded body being used as a semi-finished product, is coated with particles of the same metal with which the semi-finished product is made or with particles of a chemical compound of the metal the semi-finished product is made, wherein the compound or particles can be reduced or thermally or chemically decomposed in a thermal treatment. After the coating process, a thermal treatment in a suitable atmosphere is carried out, in which the particles are connected to the surface of the semi-finished product and/or adjacent particles such that the specific surface area of the obtained open-pore molded body is increased to at least 30 m 2 /l and/or at least by a factor of 5 in comparison to the starting material.

1 . A process for producing open-pored molded bodies comprising a metal, wherein an open-pored shaped body comprising metal as a semifinished part is coated on its surfaces with particles of the same metal, of which the semifinished part is formed or
 is coated with particles of a chemical compound of the metal of which the semifinished part is made, which chemical compound can be reduced or thermally or chemically decomposed in a thermal treatment and being formed by particles of the respective metal obtained by chemical reduction or thermal or chemical decomposition;   and   the coating is followed by at least one thermal treatment in which the particles are joined via sinter necks or sinter bridges to the surface of the semifinished part and/or adjacent particles so that the specific surface area of the open-pored molded body obtained is increased to at least 30 m 2 /l and/or by at least a factor of 5 compared to the starting material of the uncoated metallic semifinished part, with   a metal reducing atmosphere or an atmosphere suitable for the decomposition is maintained in the thermal treatment of a coated open-pored shaped body with particles of a reducible or thermally or chemically decomposable chemical compound of the metal of which the semifinished part is made, at least until the reduction or thermal or chemical decomposition of the chemical compound to form the metal is complete.   
     
     
         2 . The process as claimed in  claim 1 , wherein the particles of a metal or the particles of a chemical compound of the metal are used as powder, powder mixture and/or suspension/dispersion. 
     
     
         3 . The process as claimed in  claim 1 , wherein the application of the particles of the metal or the particles of the chemical compound of the metal as powder, powder mixture, suspension and/or dispersion is carried out by dipping, spraying, in a pressure-assisted manner, electrostatically and/or magnetically. 
     
     
         4 . The process as claimed in  claim 1 , wherein an organic and/or inorganic binder is used in solution, suspension/dispersion or as a powder in order to improve the adhesion of particles. 
     
     
         5 . The process as claimed in  claim 1 , wherein the application of particles of the metal or particles of the specified chemical compound of the metal is repeated a number of times. 
     
     
         6 . The process as claimed in  claim 1 , wherein in the case of multiple coating with particles of the metal or particles of the chemical compound of the metal, when a binder is employed, the application of the binder is repeated a number of times. 
     
     
         7 . The process as claimed in  claim 1 , wherein the application of a binder and the application of the particles of the metal or the particles of the chemical compound of the metal is carried out on different sides of the surface of the semifinished part using different amounts in order to obtain a different porosity, pore size and/or specific surface area. 
     
     
         8 . The process as claimed in  claim 1 , wherein Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, La, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce or Mg is used as metal for the semifinished part and the particles to be applied or a chemical compound of Ni, Fe, Cr, Al, Nb, Ta, Ti, Mo, Co, B, Zr, Mn, Si, La, W, Cu, Ag, Au, Pd, Pt, Zn, Sn, Bi, Ce or Mg, is used as metal for the semifinished part and particles of a reducible, thermally or chemically decomposable compound of this metal. 
     
     
         9 . The process as claimed in  claim 1 , wherein a semifinished part which has been obtained by electrochemical coating of an open-pored body of a polymeric material with the respective metal is used as semifinished part. 
     
     
         10 . A coated and sintered open-pored molded body produced by a process wherein the molded body with metallic particles joined via sinter necks or sinter bridges to the surface of a semifinished part and/or the surface of adjacent particles has a specific surface area of at least 30 m 2 /1. 
     
     
         11 . The coated and sintered open-pored molded body as claimed in  claim 10 , wherein pore size within the coated and sintered open-pored molded body corresponds to not more than 10 000 times the particle size used. 
     
     
         12 . The coated and sintered open-pored molded body as claimed in  claim 10 , wherein not more than 3% by mass of oxygen is present in the material of the coated and sintered open-pored molded body.