Heat exchanger tube precursor and method of producing the same

摘要

A heat exchanger tube precursor that allows manufacturing a heat exchanger having high corrosion resistance after brazing treatment is provided. The heat exchanger tube precursor includes: an Al alloy tube; and a flux layer including a Si powder, a Zn-containing flux, a Zn-free flux, and a binder, the flux layer being formed on an outer surface of the Al alloy tube.

主权项

1. A heat exchanger tube precursor comprising: an Al alloy tube; and a flux layer including a Si powder, a Zn-containing flux, a Zn-free flux, and a binder, the flux layer being formed on an outer surface of the Al alloy tube,
wherein the Si powder has a particle diameter distribution such that 99% particle diameter (D99) is 5 μm or more and 20 μm or less, and an amount of coarse particles having diameters of not smaller than 5 times (D99) is less than 1 ppm by volume, wherein (D99) denotes a critical diameter defined such that cumulative volume of particles not larger than (D99) constitute 99% by volume of all the particles, an amount of the Si powder applied on the Al alloy tube is in a range of 1 g/m2 to 5 g/m2, an amount of the Zn-containing flux applied on the Al alloy tube is in a range of 3 g/m2 to 20 g/m2, and 50% particle diameter (D50) of the Si powder is (D99)×0.05 or more and (D99)×0.7 or less, (D50) denoting a critical diameter defined such that cumulative volume of particles not longer than (D50) constitute 50% by volume of all the particles.