Method for bonding an aluminum rib to a steel pipe and heat exchanger having a unit produced in this way

Abstract

The invention relates to a method for bonding an aluminum rib to a steel pipe, a surface coating material of the steel pipe being used as the bonding material, so that supplying a separate soldering material, for example, may be dispensed with. The invention additionally relates to a heat exchanger which comprises a unit made of steel pipe and aluminum rib produced according to the method.

1 . A method for bonding an aluminum rib to a steel pipe comprising the following steps:
 providing at least one first component in the form of a surface-coated steel pipe, the surface coating preferably having an aluminum proportion of greater than 20 wt.-%,   providing at least one second component in the form of an aluminum rib,   which preferably comprises pure aluminum,   bringing these components into contact,   heating and subsequently holding these components in a temperature range between 470° C. and 590° C., preferably in the range between 550° C. and 585° C., a permanent bond occurring on at least one contact point of the components, in which the material of the surface coating of the first component is used as a bonding material.   
   
   
       2 . The method according to  claim 1 , characterized in that, preferably before the heating, a flux is applied at least in the area of the contact points, this being a flux based on cesium and in particular a flux based on cesium-aluminum-fluoride. 
   
   
       3 . The method according to  claim 1 , wherein the unit formed by the joining of the components is cooled down in a controlled manner after the joining. 
   
   
       4 . The method according to  claim 3 , wherein the coating for the first component has an aluminum proportion of greater than 30 wt.-%, preferably greater than 40 wt.-%, and in particular a proportion of 55 wt.-%, and the remaining proportion is essentially zinc. 
   
   
       5 . The method according to  claim 4 , wherein the heating temperature for bonding is 575° C. 
   
   
       6 . A heat exchanger having a unit produced according to a method according to  claim 5 , wherein the first component is a flat pipe. 
   
   
       7 . The heat exchanger according to  claim 6 , wherein the second component is connected to the flat pipe along a flat section thereof. 
   
   
       8 . The heat exchanger according to  claim 6 , wherein the second component at least sectionally encloses, preferably completely encloses the flat pipe around its circumference. 
   
   
       9 . The heat exchanger according to  claim 8 , wherein it is a condenser. 
   
   
       10 . A use of a unit produced according to the steps according to  claim 1  for a heat exchanger, preferably for an air-cooled heat exchanger, especially preferably for an air-cooled condenser, which is implemented in particular as a single pipe system, for use in power plants.