Die for producing a casting and method for making the die

Abstract

The invention concerns a die for producing a casting, particularly a component for a motor or other engine, from a reactive molten non-ferrous metal charge using a casting mould and a method for manufacturing the die. The die consists of a casting mould which has a front layer area which comes into contact with the reactive non-ferrous molten metal charge and a top layer area mechanically stabilising the front layer area, the front layer area consisting of a minimum of one rare earth oxide and a minimum of one additional metal oxide, the minimum of one additional metal oxide being selected from the group of oxides of the following metals: titanium and nickel.

1 . A die for producing a casting, particularly a component for a motor or other engine, from a reactive non-ferrous molten metal charge with a casting mould which has a front layer area which comes into contact with the reactive non-ferrous molten metal charge and a back-up layer area mechanically stabilising the front layer area, characterized in that the front layer area consists of a minimum of one rare earth oxide and a minimum of one additional metal oxide, the minimum of one additional metal oxide being selected from the group of oxides of the following metals: titanium and nickel. 
   
   
       2 . The die according to  claim 1 , characterized in that the minimum of one rare earth oxide is yttrium oxide. 
   
   
       3 . The die according to  claim 2 , characterized in that the yttrium oxide has purity in excess of 99.9%. 
   
   
       4 . The die according to  claim 1 , characterized in that the ratio between the minimum of one rare earth oxide and the minimum of one metal oxide is greater than 10:1 by weight. 
   
   
       5 . The die according to  claim 1 , characterized in that the front layer area and/or the back-up layer area are made by the slurry dipping and sand coating process. 
   
   
       6 . The die according to  claim 1 , characterized in that the casting mould in which the front layer area which comes into contact with the reactive non-ferrous molten metal charge contains less than 0.1% SiO 2  by weight. 
   
   
       7 . The die according to  claim 1 , characterized in that the casting mould in the front layer area and the back-up layer area is openly porous, rendering the casting mould gas-permeable. 
   
   
       8 . The die according to  claim 7 , characterized in that the casting mould in the front layer area and the back-up layer area has pores making up a volumetric proportion of between 20% and 40%. 
   
   
       9 . The die according to  claim 1 , characterized in that the casting mould in the front layer area has a surface roughness (Ra) better than 3.2 μm. 
   
   
       10 . The die according to  claim 1 , characterized in that the casting mould has a strength in excess of 13 MPa. 
   
   
       11 . The die according to  claim 1 , characterized in that the back-up layer area is formed in various grain sizes, using aluminium oxide. 
   
   
       12 . A method for manufacturing a die for the production of a casting, particularly a motor or other engine component, from a reactive non-ferrous molten metal charge, which method includes the following steps:
 Preparation of a wax blank with an external shape which reproduces the casting to be made;   Formation of a casting mould which has a front layer area which comes into contact with the reactive non-ferrous molten metal charge and a back-up layer area mechanically stabilising the front layer area, the wax blank being coated at least once with a slurry;   Drying and curing the casting mould;   Removal of the wax blank from the casting mould and firing of the casting mould; and   Firing of the casting mould; the front layer area of the casting mould consisting of a minimum of one rare earth oxide and a minimum of one additional metal oxide, the minimum of one additional metal oxide being selected from the group of oxides of the following metals: titanium and nickel.   
   
   
       13 . The method according to  claim 12 , characterized in that yttrium oxide is used as the minimum of one rare earth oxide. 
   
   
       14 . The method according to  claim 13 , characterized in that the yttrium oxide used has purity in excess of 99.9%. 
   
   
       15 . The method in accordance with  claim 12 , characterized in that the ratio of the minimum of one rare earth oxide to the minimum of one metal oxide is set greater than 10:1 by weight. 
   
   
       16 . The method in accordance with  claim 12 , characterized in that the front layer area and/or the back-up layer area are made by the slurry dipping and sand coating process when forming the casting mould, by the wax blank being dipped once or more into at least one slurry and subsequently discretionarily sand-coated. 
   
   
       17 . The method in accordance with  claim 12 , characterized in that at least one slurry is formed at feast partly with powder of the minimum of one rare earth oxide or of the minimum of one metal oxide, with a grain size measured in nanometres. 
   
   
       18 . The method in accordance with  claim 12 , characterized in that at least one slurry is water-based. 
   
   
       19 . The method in accordance with  claim 12 , characterized in that the casting mould in which the front layer area which comes into contact with the reactive non-ferrous molten metal charge contains less than 0.1% SiO 2  by weight. 
   
   
       20 . The method in accordance with  claim 12 , characterized in that the casting mould in the front layer area and the back-up layer area is openly porous, rendering the casting form gas permeable. 
   
   
       21 . The method according to  claim 20 , characterized in that the casting mould in the front layer area and the back-up layer area has pores making up a volumetric proportion of between 20% and 40%. 
   
   
       22 . The method in accordance with  claim 12 , characterized in that the casting mould in the front layer area has a surface roughness (Ra) better than 3.2 μm. 
   
   
       23 . The method in accordance with  claim 12 , characterized in that the casting mould is formed with a strength in excess of 13 MPa. 
   
   
       24 . The method in accordance with  claim 12 , characterized in that the back-up layer area is formed in various grain sizes, using aluminium oxide. 
   
   
       25 . The method in accordance with  claim 12 , characterized in that the minimum of one additional metal oxide is a metal oxide made from a metal comprised in the reactive non-ferrous molten metal charge. 
   
   
       26 . Use of a casting mould in accordance with  claim 1  to produce a casting by introducing a non-ferrous molten metal charge into the casting mould, cooling and solidifying the non-ferrous molten metal charge in the casting mould so that a casting is formed and removing the casting from the casting mould. 
   
   
       27 . The use of a casting mould according to  claim 26 , where a nickel alloy, a titanium alloy or a material forming an intermetallic compound, particularly a TiAl or an NiAl alloy, is used as the non-ferrous molten metal charge.