خوردگي حفره اي آلومينيوم خالص تجاري و ماده مركب A1-TIB2 در محلول يك مولار كلريدسديم

Pitting Corrosion of Commercially Pure Aluminum and Al-TiB2 Composite in 1 M Sodium Chloride Solution

Pitting corrosion of commercially pure aluminum and aluminum metal-matrix composite reinforced with TiB2 particles were investigated in 1M sodium chloride solution. The electrochemical methods used in this investigation were potentiodynamic and potentiostatic techniques. Potentiodynamic polarization tests were carried out in naturally aerated and deaerated solutions using various potential scan rates. The influence of bubbling nitrogen gas in solution and various potential scan rates were investigated, both for commercially pure aluminum and Al-TiB2 composites. Potentiostatic polarization tests were also carried out to determine the exact critical pitting potentials (Epit). Results showed that the reinforcing TiB2 particles had no significant influence on critical pitting potential (Epit) of aluminum matrix. The Epit value of Al-3%o TiB2 and Al-6% TiB2 was only 10 mV lower than pitting potential of commercially pure aluminum. It was also found that during the potentiodynamic polarization tests for Al-TiB2 composites, deaeration of solution as well as slow scan rate of potential change was necessary for determining the exact Epit values.