Brazing sheet and method

Abstract

The present invention is directed to a brazing sheet comprising an aluminum 3xxx series core alloy wherein at least one side thereof is provided with an aluminum clad material comprising from 0.7-2.0% Mn, 1.3-3.0% Zn, 0.05 Mg max, and 0.05-0.4% Cu. In one embodiment another side of the core is provided with an aluminum alloy comprising at least 5.5% Si. There are further provided methods for preparing brazing sheets as described herein as well as methods for use of brazing sheet materials including as tube stock and as heat exchangers, as well as other applications.

1 . A brazing sheet comprising: 
 an aluminum 3xxx series core alloy    a first layer of an aluminum clad material disposed on one side of said core alloy, wherein said first layer comprises    0.7-2.0% Mn,    1.3-3.0% Zn,    0.05% Mg max, and    0.05-0.4% Cu.    
   
   
       2 . A brazing sheet of  claim 1 , wherein another side of said core is provided with an aluminum alloy comprising at least 5.5% Si.  
   
   
       3 . (canceled)  
   
   
       4 . (canceled)  
   
   
       5 . A heat exchanger tube prepared from a brazing sheet according to  claim 1 .  
   
   
       6 . Braze tube stock prepared from a sheet according to  claim 1 .  
   
   
       7 . A method for reducing corrosion and/or erosion associated with fluid velocity in the interior of heat exchange tubes comprising: 
 providing a brazing sheet material that includes an inner clad layer wherein said inner clad layer comprises 1.3-3.0% Zn, 0.7-2.0% Mn, 0.05% Mg max, and 0.05-0.4% Cu, and    forming a heat exchanger tube wherein said inner clad is present on the interior of said heat exchanger tube.    
   
   
       8 . A method according to  claim 7 , wherein said method imparts a reduction from between 10% to 60% of the erosion/corrosion compared to AA7072 as measured by maximum pit depth in microns for fluid velocity rates from 0.9 m/second-3.0 m/second.  
   
   
       9 . A method according to  claim 7 , wherein said method imparts a reduction from between 10% to 60% of the erosion/corrosion compared to AA7072 as measured by average pit depth in microns for fluid velocity rates up to 5.0 m/second.  
   
   
       10 . A method according to  claim 7 , wherein said method imparts a reduction from between 10% to 60% of the erosion/corrosion compared to AA7072 as measured by maximum pit depth in microns for fluid velocity rates up to 5 m/second.  
   
   
       11 . A method according to  claim 7 , wherein said brazing sheet material includes an outer clad layer comprising at least 5.5% Si.  
   
   
       12 . A heat exchanger prepared according to the method of  claim 7 .  
   
   
       13 . A heat exchanger prepared using a brazing sheet according to  claim 1 .  
   
   
       14 . A brazing sheet according to  claim 1  that has a thickness of 0.007″-0.015″.  
   
   
       15 . A heat exchanger according to  claim 12 , that has been formed from a brazing sheet having a size of 0.007″-0.015″.  
   
   
       16 . (canceled)  
   
   
       17 . A heat exchanger as claimed in  claim 13 , that shows substantially no difference in maximum and/or average pit depth after being exposed to fluid velocities from 0.94 m/second-2.36 m/second for 250 hours.  
   
   
       18 . Tube stock according to  claim 6 , wherein said tube stock will have a maximum pit depth of up to 40 microns when exposed to a fluid at a velocity of 2.36 m/second for 250 hours.