Exothermic sleeve mixes containing fine aluminum

Abstract

The invention relates to an exothermic sleeve composition comprising (a) an oxidizable metal where the oxidizable metal comprises fine aluminum as the major component, and (b) an oxidizing agent capable of generating an exothermic reaction. The invention also relates to the use of the sleeve composition to prepare sleeves, the sleeves prepared with the sleeve compositions, and the use of the sleeves to prepare metal castings.

1 . An exothermic sleeve composition comprising: 
 (a) an oxidizable metal where the oxidizable metal comprises fine aluminum as the major component, and    (b) an effective amount of an oxidizing agent capable of generating an exothermic reaction.    
     
     
         2 . The composition of    claim 1    wherein the fine aluminum comprises a particle distribution such that 95 weight percent of the aluminum passes through a 100 mesh as determined by the US Standard Screen Test.  
     
     
         3 . The sleeve composition of    claim 2    wherein the fine aluminum comprises a particle distribution such that 95 weight percent passes through a 140 mesh as determined by the US Standard Screen Test.  
     
     
         4 . The composition of    claim 3    wherein the fine aluminum comprises at least 5 to 45 weight percent of the sleeve composition.  
     
     
         5 . The sleeve composition of    claim 4    wherein the sleeve composition contains from 30 weight percent to 80 weight percent of hollow alumina microspheres, where said weight is based upon the total weight of the sleeve composition.  
     
     
         6 . The sleeve composition of    claim 4    wherein the sleeve composition contains sand as a refractory in an amount of 30 weight percent to 70 weight percent based upon the total weight of the sleeve composition.  
     
     
         7 . A sleeve mix comprising the sleeve composition of    claim 1   ,    2   ,  3 ,  4 ,  5 , or  6  and an effective binding amount of an organic foundry binder.  
     
     
         8 . A cold-box process for making an exothermic sleeve comprising: 
 (A) introducing the sleeve mix of    claim 7    into a sleeve pattern to prepare an uncured sleeve;    (B) contacting said uncured sleeve prepared by (A) with a vaporous curing catalyst;    (C) allowing said sleeve resulting from (B) to cure until said sleeve becomes handleable; and    (E) removing said sleeve from the pattern.    
     
     
         9 . The process of    claim 8    wherein the binder is selected from the group consisting of phenolic urethane binders and epoxy-acrylic binders.  
     
     
         10 . The process of    claim 9    wherein the binder level is from about 4 weight percent to about 12 weight percent based upon the weight of the sleeve composition.  
     
     
         11 . A sleeve prepared by the process of    claim 10   .  
     
     
         12 . A process for casting a metal part which comprises: 
 (1) using an exothermic sleeve of    claim 11    in a mold assembly of a casting assembly;    (2) pouring metal, while in the liquid state, into said casting assembly;    (3) allowing said metal to cool and solidify; and    (4) then separating the cast metal part from the casting assembly.    
     
     
         13 . A metal part prepared in accordance with    claim 12   .