| 摘要 |
PURPOSE:To continuously produce an Al tube material for a heat exchanger with a Zn coating layer having superior adhesion and uniformity at a high speed and a low cost by tubularly extruding an Al material and subjecting the resulting tube material to degreasing, cleaning, Zn substitution treatment and contact plating. CONSTITUTION:An Al material is tubularly hot- or warm-extruded. The resulted tube material is well degreased and cleaned with trichloroethylene or the like. The clean material is subjected to Zn substitution treatment by immersion in a soln. contg. essentially NaOH and ZnO. Contact plating is then carried out with a graphite electrode coated with cotton cloth or the like impregnated with an electrolytic soln. contg. ZnO and ZnSO4. Thus, a Zn coating layer of 0.5-10mum thickness is formed on the surface of the extruded tube material and a tube material for an Al heat exchanger having superior pitting corrosion resistance is obtd.
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