SODIUM CHROMATE AS INHIBITOR FOR AL AND ITS ALLOYS AT pH=11 | Journal of Applied Chemical Science..

Corrosion inhibition of Al, Al-Cu, Al-Mg, and Al-Zn in 0.001 M NaOH solution at pH=11 was studied at four temperatures: 298, 303, 308, and 313 K, using sodium chromate as an inhibitor at three concentrations: 510-3, 110-2, and 510-2 M. The protection efficiencies show that sodium chromate is an effective inhibitor for Al and its alloys. Because it changed corrosion potentials to noble or active directions, sodium chromate acted as a mixed-type inhibitor. Tafel slopes increased when chromate was present in corrosive liquid. Due to differences in cathodic and anodic locations on metal surfaces, activation energies were altered.

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