COMPLEX IONS AND STRESS CORROSION CRACKING OF ALPHA-BRASS

Abstract

A study was made of the stress-corrosion cracking, rate of weight loss, and surface condition of an alloy containing 70% copper and 30% zinc in 15N aqueous ammonia. The behavior is shown to be strongly dependent on the concentration of the cupric complex ion Cu(NH3)5(2+) present in the environment. Stress-corrosion life decreased significantly with increasing complex-ion concentration, the relationship exhibiting a well-defined inflection at a critical concentration. Specimens immersed in solutions of concentrations exceeding the critical value were tarnished, while those exposed to less concentrated solutions appeared tarnish-free. These and other observations indicate that two mechanisms of stress-corrosion cracking are operative, one in the presence of tarnish and the other in the absence of this layer. Possible mechanisms are discussed. A model has been developed to explain the dependence of the tarnishing reaction on the chemical composition of the environment.

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Document Details

Document Type
Technical Report
Publication Date
Aug 01, 1965
Accession Number
AD0470947

Entities

People

  • A. R. Westwood
  • E. N. Pugh

Organizations

  • Martin Marietta

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Body Weight
  • Chemistry
  • Copper
  • Corrosion
  • Electron Diffraction
  • Engineering
  • Hydroxides
  • Layers
  • Materials
  • Metals
  • Microscopes
  • New York
  • Particles
  • Sodium Hydroxide
  • Stress Corrosion
  • Stress Corrosion Cracking
  • Surface Properties

Readers

  • Electrochemical Engineering/ Fuel Cell Technologies
  • Materials Science (Mechanical Engineering).
  • Materials Science and Engineering.