Surface Chemical Factors in the Stress-Corrosion Cracking off Alpha Brass

Abstract

Stress corrosion cracking of alpha brass in ammonia solutions containing copper-ammonia complexes is most rapid in the pH range 6 to 7, where weight loss corrosion is insignificant, Linear relationships were found for (a) log 1/tc (tc = cracking time) vS log Cu++ (initial copper concentration) and (b) l/tc vs 1/T (T = absolute temperature). Oxygen appears necessary for general corrosion and cracking at pH values above 8. Rapid cracking is interpreted in terms of a drastic surface free energy decrease caused by the adsorption of an intermediate copper-zinc- ammonia complex (not yet identified) which is catalytically formed at the brass/solution interface and is surface active. It is suggested also that linear relationships like (a) and (b) above may be distinguishing features of stress corrosion cracking mechanisms which involve surface energy lowering.

Electrochemical impedance study on brass corrosion in NaCl and (NH4)2SO4 solutions during cyclic wet?dry conditions

“…The surface attained a steady state during cycles number 5 and 7 at 293 and 313 K, respectively. This result can be attributed to the low dissolution process of the corrosion products, which leads to the rapid passivation of the surface at 293 K. X-ray diffraction analysis indicated that the films formed on brass were predominantly Cu 2 O and Zn 5 (OH) 8 Cl 2 H 2 O; this is consistent with the results reported previously for brass tested in tarnishing solutions [28][29][30] as well as in a marine environment [31]. The results reported previously indicated an increase in the corrosion rate with increase in temperature [32].…”

Critical Potentials for Stress Corrosion Cracking of 63‐37 Brass in Ammoniacal and Tartrate Solutions

“…The composition conformed approximately to that recommended earlier by Mattsson (18), and by Johnson and Leja (14) for producing minimum failure times; it consisted of 0.05M CuSO4 and 1.0M (NH4)eSO4 of pH 6.5 adjusted using NH4OH. The composition conformed approximately to that recommended earlier by Mattsson (18), and by Johnson and Leja (14) for producing minimum failure times; it consisted of 0.05M CuSO4 and 1.0M (NH4)eSO4 of pH 6.5 adjusted using NH4OH.…”

“…4). Johnson and Leja (14) reported for 69.5% Cu-30.5% Zn brass in 0.04M Cu, 1.SM total NH3, pH 6.8 solution, a variable activation energy ranging from 4 to 11.5 kcal/mole. This value agrees with that of 9.9 kcal/mole reported by Pugh et aI.…”

“…); (it) progressive fracture of an oxide or other type reaction product film covering the alloy surface (9-13); or (iii) reduction of metal bond strength by an adsorbate (14,15), called by one of us "stress-sorption cracking" (16). ); (it) progressive fracture of an oxide or other type reaction product film covering the alloy surface (9-13); or (iii) reduction of metal bond strength by an adsorbate (14,15), called by one of us "stress-sorption cracking" (16).…”

Die Korrosion von Messing in Ammoniumchloridlösungen

“…Die Ammoniumionen schienen uns deshalb von besoiiderem Interesse, weil sie liisliche Kupfer-Ammoniuinkomplexe bilden koiineii uiid aderdeiii Ammoniumioneii in neutralen uiid alkalischen Losungen die Ursaclie von Korrosioiis-KiRbildung a n Messing sind (29)(30)(31)(32)(33)(34)(35)(36) 3.31 C~77Zii21.412As'~' (2) 76,2 2,11 3,23…”