| Summary: | 碩士 === 逢甲大學 === 材料科學所 === 92 === Dissolved oxygen in aqueous solution has been lowered to 3.17ppb by various physical and chemical method. The corrosion behaviors of metals in aqueous solution with different amounts of dissolved oxygen have been investigated, too.
Aqueous NaCl solution with dissolved oxygen 8.32ppm, 2ppm, 500ppb, or 3.17ppb in acidic, neutral, or alkaline condition was used as corrosion environment for low-carbon steel, copper, and electroless-nickel plated species. Based on potentiodynamic polarization test results, electroless-nickel plated sample with higher amount of phosphorus in deposit has the lowest corrosion current density. Low-carbon steel and copper exhibit uniform corrosion and pitting surface. Electroless nickel coating begins to peel after crevice corrosion has been developed on the coating layer. Degree of corrosion is decreased as dissolved oxygen in aqueous solution lowered.
In acidic NaCl solution with 8.32ppm dissolved oxygen, more copper (Ⅱ) oxide was formed on the surface of copper at -0.2V(vs. Ag/AgCl). However, copper (Ⅰ) oxide was formed along with copper (Ⅱ) oxide at 0.2V(vs. Ag/AgCl).
Preparation of polyalloy metallic powders by zincating or electroless nickel plating for Zn-Al or Ni-P-Fe under different amounts of dissolved oxygen has been performed. Anti-corrosion behavior and electromagnetic interference shielding efficiency of paints made by Zn-Al and Ni-P-Fe powders prepared in aqueous solutions with removal of dissolved oxygen are much superior to those in untreated solutions.
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