Aluminum alloy tube and heat exchanger, and method of metal spraying a filler alloy

摘要

There is disclosed an aluminum alloy tube whose outer surface is covered with a filler alloy by metal-spraying, wherein the base material of the tube has an uneven rough surface with the depth of 10 mu m or more, and the difference between the highest projection of the base material surface and the highest projection of the filler alloy layer covering it is 3 to 25 mu m; a heat exchanger, which is assembled by using the tubes; and a method of metal-spraying, which comprises metal-spraying an aluminum alloy filler powder in a melted state, by the high-velocity flame metal-spraying process, in which the filler contains 15 to 50% Si by weight, and the powder is mainly made up of particles whose diameter is 10 mu m to 70 mu m. The aluminum alloy tube is excellent in brazability and corrosion resistance, and by using the tube, it is possible to assemble a heat exchanger without allowing locally filler-unbonded parts to be formed. Further, according to the method of metal-spraying, it is possible to form a excellent filler alloy layer, and obtain a tube high in brazability and corrosion resistance.