High porosity three-dimensional structures in chromium based alloys

Abstract

The invention relates to metallic products and a process for producing these which allows, despite the complexity of their structure, for them to be produced in refractory alloys based on chromium. The chromium is deposited by electrolysis, this being carried out by means of a bath with high throwing power. The formation of the alloy with layers of other metallic constituents is obtained by thermal diffusion. The provision of aluminium is controlled in the form of particles by immersing, by spraying or “painting”. The structures according to the invention are particularly intended to be used as catalyst supports or filtering agents.

1 . Production process for “three-dimensional” metallic structures with high porosity, of reticular honeycomb types, in refractory alloys, characterized in that this alloy contains chromium and that the provision of chromium is carried out by electrolytic deposition, the three-dimensional structure being a non-sintered sponge, a felt or a woven item.  
     
     
         2 . Production process for metallic structures according to    claim 1   , characterized in that this alloy contains chromium and that the provision of chromium is carried out by electrolytic deposition in a bath containing potassium and/or sodium dichromate.  
     
     
         3 . Production process for metallic structures according to    claim 1   , characterized in that said refractory alloys are ternary or quaternary, of nickel-chromium-aluminium, iron- chromium-aluminium or nickel- iron- chromium types.  
     
     
         4 . Production process for metallic structures according to claims  1  and  3 , characterized in that the provision of aluminium is carried out by immersing in a slip containing aluminium particles in suspension.  
     
     
         5 . Production process for metallic structures according to claims  1  and  3 , characterized in that the provision of aluminium is carried out by spraying a suspension of aluminium particles.  
     
     
         6 . Production process for metallic structures according to claims  1  and  3 , characterized in that the provision of aluminium is carried out by painting the structure using a lacquer or paint containing aluminium particles.  
     
     
         7 . Production process for metallic structures according to claims  1  and  3 , characterized in that the iron and/or nickel are provided by electrolytic deposition(s).  
     
     
         8 . Production process for metallic structures according to    claim 1   , characterized in that the alloy is produced by thermal diffusion treatment of its various constituents.  
     
     
         9 . Production process for metallic structures according to    claim 1   , characterized in that the chromium electrolysis bath contains 25% and 150% of potassium or sodium dichromate by weight relative to the chromic acid.  
     
     
         10 . “Three-dimensional” metallic structures with high porosity, in refractory alloys, of reticular honeycomb types, characterized in that these alloys contain chromium and that the chromium is deposited by electrolytic route, the alloy being obtained by thermal diffusion treatment of its various constituents and the three-dimensional structure being a non-sintered sponge, a felt or a woven item.  
     
     
         11 . Metallic structures according to    claim 10   , characterized in that the refractory alloys are ternary or quaternary, of nickel-chromium-aluminium, iron-chromium-aluminium or nickel-iron-chromium-aluminium types, the aluminium being provided in the form of particles in a slip, in a lacquer or paint, or in a sprayable suspension.