Exothermic reaction mixtures

Abstract

Disclosed herein are exothermic reaction mixtures that can be used for copper-based thermite reactions. The disclosed exothermic reaction mixtures can be advantageously formulated with synthetically made copper oxide(s), which can improve consistency and stability of thermite reactions. An example exothermic reaction mixture includes an alloy comprising copper and aluminum and a metal oxide comprising Cu 2 O and CuO. Also disclosed are methods of preparing the exothermic reaction mixture and methods of welding that include the exothermic reaction mixture.

What is claimed is: 
     
         1 . An exothermic reaction mixture comprising:
 an alloy, the alloy comprising copper (Cu) and aluminum (Al); and   a metal oxide, the metal oxide comprising
 about 60% to about 75% Cu 2 O by mass of the mixture, and 
 no more than 7.5% CuO by mass of the mixture. 
   
     
     
         2 . The exothermic reaction mixture of  claim 1 , comprising an additive selected from the group consisting of a scavenging agent, a fluxing agent, a stabilizing agent, a buffering agent, and a combination thereof. 
     
     
         3 . The exothermic reaction mixture of  claim 2 , comprising a scavenging agent that is CaSi 2 . 
     
     
         4 . The exothermic reaction mixture of  claim 3 , comprising CaSi 2  at no more than 1.5% by mass of the mixture. 
     
     
         5 . The exothermic reaction mixture of  claim 2 , comprising a fluxing agent that is tin. 
     
     
         6 . The exothermic reaction mixture of  claim 5 , comprising tin at no more than 2% by mass of the mixture. 
     
     
         7 . The exothermic reaction mixture of  claim 2 , comprising a stabilizing agent that is CaF 2 , LiF, I 2 O 5 , or a combination thereof. 
     
     
         8 . The exothermic reaction mixture of  claim 7 , comprising, by mass of the mixture:
 about 1% to about 2% CaF 2 ; or   about 0.5% to about 2% LiF.   
     
     
         9 . The exothermic reaction mixture of  claim 1 , comprising, by mass of the mixture, about 20% to about 22% of the alloy. 
     
     
         10 . The exothermic reaction mixture of  claim 1 , comprising, by mass of the mixture, about 60% to about 83% of the metal oxide. 
     
     
         11 . The exothermic reaction mixture of  claim 1 , comprising, by mass of the mixture:
 about 20% to about 22% of the alloy;   about 67% to about 72% Cu 2 O;   no more than 7.5% CuO;   about 1% to about 2% CaSi 2 ; and   about 1% to about 5% CaF 2 .   
     
     
         12 . The exothermic reaction mixture of  claim 1 , wherein the alloy comprises, by mass of the alloy,
 about 47% to about 53% copper (Cu); and   about 47% to about 53% aluminum (Al).   
     
     
         13 . The exothermic reaction mixture of  claim 1 , wherein the metal oxide comprises, by mass of the metal oxide,
 about 90% to about 100% Cu 2 O, and   no more than 10% CuO.   
     
     
         14 . The exothermic reaction mixture of  claim 1 , comprising a mass ratio of the metal oxide to a combination of the alloy and CaSi 2  of about 3:1 to about 9:2. 
     
     
         15 . The exothermic reaction mixture of  claim 1 , wherein the alloy is a powder having an average particle size of about 100 μm to about 500 μm. 
     
     
         16 . The exothermic reaction mixture of  claim 1 , wherein the metal oxide is a powder having an average particle size of about 250 μm to about 350 μm. 
     
     
         17 . The exothermic reaction mixture of  claim 1 , wherein the metal oxide is synthetically made. 
     
     
         18 . The exothermic reaction mixture of  claim 1 , wherein the mixture has a combustion temperature that is greater than a melting temperature of the alloy and less than a boiling point of the alloy. 
     
     
         19 . The exothermic reaction mixture of  claim 1 , comprising a non-transition metal, a transition metal, an alloy of a non-transition metal, an alloy of a transition metal, an alloy of a transition metal and a non-transition metal, or a combination thereof. 
     
     
         20 . The exothermic reaction mixture of  claim 19 , wherein the transition metal is copper (Cu). 
     
     
         21 . An exothermic reaction mixture comprising:
 an alloy, the alloy comprising copper (Cu) and aluminum (Al);   a metal oxide, the metal oxide comprising a mass ratio of Cu 2 O to CuO of about 9:1;   CaSi 2 ;   CaF 2  or LiF; and   tin.   
     
     
         22 . A method of welding, the method comprising:
 placing at least two components into a mold;   adding an exothermic reaction mixture according to  claim 1  to a crucible, the crucible being positioned on top of the mold;   heating the exothermic reaction mixture to initiate an exothermic reaction that produces a liquid metal derived from the exothermic reaction mixture; and   directing the liquid metal to contact the at least two components thereby joining the at least two components together.   
     
     
         23 . The method of  claim 22 , wherein the mold comprises graphite or a ceramic. 
     
     
         24 . The method of  claim 22 , wherein the exothermic reaction mixture is provided as a powder or a pellet. 
     
     
         25 . The method of  claim 22 , wherein the crucible comprises graphite or a ceramic. 
     
     
         26 . The method of  claim 22 , wherein a copper yield of the exothermic reaction is greater than or equal to  75 % by mass of the mixture. 
     
     
         27 . The method of  claim 22 , wherein a conductivity of the joined components is greater than or equal to 4Ω. 
     
     
         28 . The method of  claim 22 , wherein heating the exothermic reaction mixture produces a slag, the slag comprising, by mass of the slag:
 about 0% to about 30% CaO;   about 0% to about 64% SiO 2 ;   about 6% to about 83% Al 2 O 3 ;   about 0% to about 3% CaF 2 ;   about 0% to about 5% AlF 3 ;   about 0% to about 2% CaSi 2 ; and   about 0% to about 1% Ca 2 SiO 4 .   
     
     
         29 . The method of  claim 22 , wherein heating the exothermic reaction mixture produces a slag, the slag comprising, by mass of the slag:
 about 5% to about 30% CaO;   about 12% to about 64% SiO 2 ;   about 6% to about 83% Al 2 O 3 ;   about 0% to about 3% CaF 2 ;   about 0% to about 5% AlF 3 ;   about 0% to about 2% CaSi 2 ; and   about 0% to about 1% Ca 2 SiO 4 .   
     
     
         30 . The method of  claim 22 , wherein the exothermic reaction mixture comprises a molar ratio of aluminum to CaSi 2  of about 2:1, and wherein heating the exothermic reaction mixture produces a slag comprising CaAl 2 Si 2 O 8 . 
     
     
         31 . The method of  claim 22 , wherein the exothermic reaction mixture comprises a molar ratio of aluminum to CaSi 2  of about 10:1, and wherein heating the exothermic reaction mixture produces a slag comprising Al 2 O 3 :CaAl 2 Si 2 O 8 at a molar ratio of about 4:1.