Method of producing a corrosion resistant aluminum heat exchanger
An aluminum heat exchanger having increased resistance to galvanic corrosion. The exterior of one end of the aluminum tube or connector is coated with a metal or metal alloy. This end is brazed onto a copper or copper alloy inlet or outlet tube. The metal or metal alloy coating inhibits the formation of galvanic corrosion.
1. A method of forming a corrosion resistant aluminum-copper heat exchanger, the method comprising:
providing at least one aluminum tube for conveying a pressurized fluid;
providing at least one aluminum connector, having an exterior and an interior;
at least partially coating one end of the exterior of the at least one aluminum connector;
providing a cladding material for brazing the aluminum tube to the aluminum connector;
brazing the aluminum tube to the uncoated end of the aluminum connector in a controlled atmosphere brazing oven;
providing at least one copper tube;
providing a cladding material for brazing the at least partially coated end of the aluminum connector to the copper tube;
brazing the partially coated end of the aluminum connector to the copper inlet tube or copper outlet tube; and,
wherein the coated end of the aluminum connector is coated with a metal having a higher solidus temperature than the brazing temperature used to braze the aluminum connector to the copper tube.
2. The method of claim 1 , wherein the metal is selected from the group consisting of nickel, nickel alloy, chromium, and chromium alloy.
3. The method of claim 1 , wherein the aluminum connector is coated by an electroless plating process.
4. The method of claim 1 , wherein the aluminum connector is coated by electroplating.
5. The method of claim 1 , wherein the thickness of the metal or metal alloy coating is 0.0001″-0.001″.
6. The method of claim 1 , wherein the density of the metal is greater than 95% of the theoretical maximum density of the metal or the density of the metal alloy coating is greater than 95% of the theoretical maximum density of the metal alloy.
7. The method of claim 1 , wherein the copper tube is an inlet tube.
8. The method of claim 1 , wherein the copper tube is an outlet tube.
9. The method of claim 1 , wherein the heat exchanger is a plate fin type heat exchanger.
10. The method of claim 1 , wherein the heat exchanger is finless.
11. The method of claim 1 , wherein the heat exchanger is a microchannel type heat exchanger.