Method of coating a device, particularly a heat exchanger tube

Abstract

A method of making a heat exchanger tube having higher corrosion resistance is provided. The heat exchanger tube includes an Al alloy extruded tube, and a flux layer containing a Si powder and a Zn-containing flux formed on the external surface of the Al alloy extruded tube, wherein an amount of the Si powder applied to the Al alloy extruded tube is not less than 1 g/m 2 and not more than 5 g/m 2 , and an amount of the Zn-containing flux applied to the Al alloy extruded tube is not less than 5 g/m 2 and not more than 20 g/m 2 .

1 - 4 . (canceled)  
   
   
       5 . A method of producing a heat exchanger comprising: 
 applying Si powder to an external surface of an Al alloy extruded tube with an extrusion profile including a plurality of internal passages in a quantity of at least 1 g/m 2  and not more than 5 g/m 2 , and further applying an amount of Zn-containing flux mixed with the Si powder, in a quantity of at least 5 g/m 2  and not more than 20 g/m 2 ; and    heating the Al alloy extruded tube to a temperature sufficient to fuse the Si powder so as to braze the Al alloy extruded tube to header pipes and fins of the heat exchanger.    
   
   
       6 . The method according to  claim 5 , wherein the Zn-containing flux contains at least one Zn compound selected from ZnF 2 , ZnCl 2 , and KZnF3.  
   
   
       7 . The method according to  claim 5 , wherein the maximum particle size of the Si powder is 30 μm or smaller.  
   
   
       8 . The method according to  claim 5 , wherein the Al alloy extruded tube contains, by weight, between about 0.5% and about 1.0% Si, and between about 0.05% and about 1.2% Mn, with a balance being substantially Al.  
   
   
       9 . The method according to  claim 5 , wherein the Zn-containing flux contains at least one Zn compound selected from the group consisting of ZnF 2  and KZnF 3 .  
   
   
       10 . The method according to  claim 5 , wherein the applying of Zn-containing flux mixed with the Si powder comprises spraying.