Method for the production of a muffle for precision or model casting, method for the production of a metallic, ceramic or glass ceramic casting or blank and kit for the production of such a casting or blank

Abstract

Methods are described for the production of a muffle for precision or model casting having the following steps: preparation of a pattern preparation of an investment, comprising a mixture of: a) a dispersing agent, b) a ceramic powder containing (i) a fraction having a diameter of less than 500 nm (nanoceramic powder fraction) in a proportion of 2-74% (V/V), based on the volume of the total mixture, and (ii) a fraction having a diameter of more than 500 nm (microceramic powder fraction) in a proportion of 2-74% (V/V), based on the volume of the total mixture c) optionally a metal powder consisting of metals and/or alloys and/or intermetallic compounds, d) optionally one or more further additives and e) optionally inorganic or organic binder investing or covering the pattern with the investment solidification of the investment investing or covering the pattern by a) freezing, b) gelling, in particular on the basis of a change in pH value and/or c) dehydrating, during and/or after the solidification, drying the investment investing or covering the pattern by removing the dispersing agent and optionally other volatile constituents removal of the pattern from the dry investment and heating the dried investment so that a muffle for the precision or model casting results.

1 . Method for the production of a muffle for precision or model casting having the following steps: 
 preparation of a pattern;    preparation of an investment, comprising a mixture of: 
 a) a dispersing agent,  
 b) a ceramic powder containing 
 (i) a fraction having a diameter of less than 500 nm (nanoceramic powder fraction) in a proportion of 2-74% (V/V), based on the volume of the total mixture,  
 and  
 (ii) a fraction having a diameter of more than 500 nm (microceramic powder fraction) in a proportion of 2-74% (V/V), based on the volume of the total mixture  
 
 c) optionally a metal powder consisting of metals and/or alloys and/or intermetallic compounds,  
 d) optionally one or more further additives and  
 e) optionally inorganic or organic binder;  
   investing or covering the pattern with the investment;    solidification of the investment investing or covering the pattern by 
 a) freezing,  
 b) gelling, in particular on the basis of a change in pH value and/or  
 c) dehydrating;  
   during and/or after the solidification, drying the investment investing or covering the pattern by removing the dispersing agent and optionally other volatile constituents; and    removal of the pattern from the dry investment and heating the dried investment so that a muffle for the precision or model casting results.    
     
     
         2 . Method according to  claim 1 , wherein, for production of the investment, 
 a sol of the nanoceramic powder fraction in the dispersing agent is prepared; and    this sol is mixed with the microceramic powder fraction, optionally the metal powder and optionally the further additive or additives.    
     
     
         3 . Method according to  claim 1 , wherein the dispersing agent is water, an alcohol or an aqueous or alcoholic mixture of liquids and optionally contains one or more wetting agents and/or stabilisers and/or antimicrobial active substances.  
     
     
         4 . Method according to  claim 1 , wherein the mixture contains 
 a metal powder and/or    a microceramic powder fraction and/or    one or more further additives which (a) can be reacted with one another and/or with gaseous reactants to give an increase in volume or (b) by means of thermal activation can be induced to a change in the crystal lattice (phase change) and thus to an increase in volume, and 
 wherein the investment is so treated after solidification, optionally with the addition of one or more gaseous reactants and/or gas-forming reactants, that the metal powder and/or the ceramic powder and/or one or more of the further additives (a) react chemically or (b) perform a phase change giving rise to an increase in size.  
   
     
     
         5 . Method according to  claim 4 , wherein the treatment leading to the increase in volume takes place during heating of the investment.  
     
     
         6 . Method according to  claim 4 , wherein the investment is treated with the addition of a gaseous reactant that has been selected from the group consisting of oxygen, nitrogen, carbon monoxide, carbon dioxide and mixtures thereof.  
     
     
         7 . Method according to  claim 1 , wherein said metal powder comprises 
 a powder of a metal and/or    a mixture of powders of metals, and/or    a powder of an alloy or compound of two or more metals selected from the group that consists of: aluminium, magnesium, zirconium, niobium, yttrium, hafnium, vanadium, calcium, potassium, tantalum, titanium, iron, silicon, germanium, molybdenum, manganese, zinc, tin, bismuth, nickel and cobalt.    
     
     
         8 . Method according to  claim 1 , wherein the microceramic powder fraction consists of oxides, mixed oxides, silicides, nitrides and/or carbides of one or more elements that have been selected from the group consisting of: lithium, beryllium, boron, sodium, magnesium, aluminium, silicon, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, hafnium, tin, cadmium, lead, strontium, barium and antimony.  
     
     
         9 . Method according to  claim 1 , wherein the microceramic powder fraction has a proportion of 30-60% (V/V), based on the volume of the total mixture.  
     
     
         10 . Method according to  claim 1 , wherein the nanoceramic powder fraction comprises one, two or more ceramic compounds that have been chosen from the group that consists of: SiO 2 ; Al 2 O 3 , in particular boehmite; ZrO 2 ; yttrium oxide; yttrium salts; zirconium nitrate; and TiO 2 .  
     
     
         11 . Method according to  claim 1 , wherein the nanoceramic powder fraction has a proportion of 2-30% (V/V), based on the volume of the total mixture.  
     
     
         12 . Method according to  claim 1 , wherein the metal powder consists essentially of particles with a particle size in the range of 100 nm to 500 μm.  
     
     
         13 . Method according to  claim 1 , wherein the metal powder consists essentially of particles with a particle size in the range of 0.5 μm, to 100 μm.  
     
     
         14 . Method according to  claim 1 , wherein the investment does not contain an organic binder.  
     
     
         15 . Method according to  claim 1 , wherein the investment for investing or covering the pattern contains 20-70% (V/V) solids, based on the total volume.  
     
     
         16 . Method for the production of a metallic, ceramic or glass ceramic casting or blank, comprising the following steps: 
 production of a muffle in accordance with a method according to  claim 1 , and    either (a) duplicate casting of the muffle with a metal or a metallic alloy or (b) injecting a flowable (i) ceramic or (ii) glass ceramic composition.    
     
     
         17 . Method according to  claim 16 , wherein 
 the conditions for the production of the muffle, including the selection of the constituents of the mixture for the production of the investment, and    the conditions (a) when duplicate casting, including the selection of the metal or of the metallic alloy, or (b) when injecting the ceramic or glass ceramic composition,    are so matched to one another that during the production of the muffle an increase in volume is produced that at least partially compensates for the contraction in the volume of the metal or of the metallic alloy or of the ceramic or glass ceramic composition on solidification after duplicate casting or injection in the muffle.    
     
     
         18 . Kit for the production of a metallic and/or ceramic and/or glass ceramic casting or blank, comprising: 
 (a) one or more components, in total comprising the following constituents: 
 a sol of a ceramic powder with particles of a diameter of less than 500 nm (nanoceramic powder fraction) in a dispersing agent,  
 a ceramic powder with particles of a diameter of more than 500 nm (microceramic powder fraction),  
 a metal powder and  
 optionally one or more further additives,  
 wherein the constituents are so matched to one another that a muffle for precision or model casting can be produced therefrom, and  
   (b) (i) a metal or a metallic alloy,    wherein the constituents and the metal or the metallic alloy are so matched to one another that during the production of a muffle from the constituents an increase in volume can arise that at least partially compensates for the contraction in volume of the metal or of the metallic alloy on solidification after duplicate casting in the muffle    and/or 
 (ii) a ceramic or glass ceramic,  
   wherein the constituents and the ceramic or the glass ceramic are so matched to one another that during production of a muffle from the constituents an increase in volume can arise that at least partially compensates for the contraction in volume of the ceramic or the glass ceramic on solidification after filling the muffle.    
     
     
         19 . Kit according to  claim 18 , characterized in that said kit contains a first slip comprising at least two components.  
     
     
         20 . Kit according to  claim 19 , characterized in that said kit comprises the dispersing agent or a second slip in addition to said first slip.