Patent ID: 8815022
Filing Date: 2014-08-26
Classification: B23K,C08K,C09D,C23C,C23G,F28F

Abstract:
1. A method for surface treating a heat exchanger, comprising: (1) a pickling treatment step of causing an acidic cleaning agent to come into contact with a non-corrosive flux brazed heat exchanger made of an aluminum material; (2) a chemical conversion treatment step of causing a zirconium-based chemical conversion treatment agent to come into contact with the aluminum material after the pickling treatment step; and (3) a deodorizing treatment step of causing a surface treatment agent to come into contact with the aluminum material after the chemical conversion treatment step, wherein the acidic cleaning agent contains nitric acid and sulfuric acid, and contains 0.01 to 0.05% by mass of a ferric salt, and wherein the surface treatment agent contains silica grains coated by a vinyl alcohol polymer, and a polyallylamine resin, a total content of the silica grains and the vinyl alcohol polymer contained in the surface treatment agent being in the range of 0.2% by mass to 25% by mass, a mass ratio of the silica grains to the vinyl alcohol polymer being in the range of 30:70 to 70:30, and a content of the polyallylamine resin being the range of 100 ppm to 5000 ppm.