5642
Shaimaa Esmat Abd Elhamid Abd Elaziz
Corrosion behaviour of some copper alloys in LiBr solutions used in refrigeration absorption systems
Corrosion, Copper alloys, LiBr, Refrigeration absorption systems, SEM, EDX, Amino acids
The present work was focuced on the corrosion behaviour of Cu-alloys in different concentrations of LiBr solutions as used in refrigeration absorption systems. The potentiodynamic cyclic polarization behaviour of Cu based alloys in LiBr solutions studied from 10-2 up to 9 M. We investigated the surface by Scanning Electron Microscope (SEM) attached with Energy Dispersive X-ray (EDX) after the experiments ended. Moreover, solution analysis by Atomic Absorption spectroscopy (AAS) was helpful to complement and support the results of SEM and EDX. The results showed that Cu/30 Ni was more corrosion resistance than other investigated alloys. In industrial field, Cu alloys were used for heat exchangers tubes and pipes in absorption refrigeration systems in high concentrations of LiBr solutions from 350 to 850 g/l (≈ 4-9 M). At these concentrations, major type of corrosion was due to the pitting corrosion. General dissolution occurred in our studies. So, the effect of cations such as Cu,Al, Zn and Ni on the dissolution of Cu/30 Ni at higher LiBr concentrations from 4 to 9 M was investigated. Pitting corrosion taken place with LiBr contain different corrosion product. This was attributed to the dissolution of any Cu-alloys in a circulating system was occurred by general dissolution where CuBr2- soluble complex produced. Consequently, CuBr2- play a role in the deposition of Cu2O on the outer surface by hydrolysis which increase at the thickness of Cu2O to becomemore protective enough to produce pitting attack at the weak points on the surface.
2020
Ph.d
Ain Shams
Science