Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
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Use of Hydrazine for Pitting Corrosion Inhibition of Copper Sprinkler Tubes: Reaction of Hydrazine with Corrosion By-Products

  • Suh, Sang Hee (Center for Electronic Materials, Korea Institute of Science and Technology) ;
  • Kim, Sohee (Advanced Analysis Center, Korea Institute of Science and Technology) ;
  • Suh, Youngjoon (Center for Electronic Materials, Korea Institute of Science and Technology)
  • Received : 2017.09.13
  • Accepted : 2017.10.27
  • Published : 2017.10.31
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Abstract

The feasibility of using hydrazine for inhibiting pitting corrosion in copper sprinkler tubes was investigated by examining microscopical and structural evolution of corrosion by-products with SEM, EDS, and XRD. Hydrazine removed dissolved oxygen and reduced CuO and $Cu_2O$ as well. The stable phase was changed from CuO to $Cu_2O$ or Cu depending on hydrazine concentration. Hydrazine concentration of 500 ppm could convert all CuO corrosion by-products to $Cu_2O$. In a tightly sealed acryl tube filled with aqueous solution of 500 ppm hydrazine, octahedral $Cu_2O$ particles were formed while plate-like structures with high concentration of Cu, O, N and C were formed near a corrosion pit. The inside structure of a corrosion pit was not altered by hydrazine aqueous solution. Uniform corrosion of copper was almost completely stopped in aqueous solution of 500 ppm hydrazine. Corrosion potential of a copper plate was linearly dependent on log (hydrazine concentration). The concept of stopping pitting corrosion reaction by suppressing oxygen reduction reaction could be verified by applying this method to a reasonable number of real sprinkler systems before full-scale application.

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