Nanocoating and Electrospraying Techniques Used for Corrosion Mitigation of Aluminum in Nitrogen dioxide Environment

Abstract

Nitrogen gas absorbs moist air to produce nitric acid. It develops acidic medium for aluminum. It forms a corrosion cell on the surface of aluminum. The formation of corrosion cell is written as: Al|Al⁺³||H⁺|H₂ thus Corrosion reactions accelerate on aluminum surface and Al is oxidized into Al⁺³ and the H⁺ ions is reduced into H₂. This acid produces various forms of corrosion in aluminum like galvanic, pitting, stress, crevice, blistering, embrittlement and intergranular. These types of corrosion destroy metal and its mechanical properties. The noble composite barrier is developed on the surface of aluminum by nanocoating of tetrahydro-dibenzo[a,d][7]annulene-5,11-disemicarbazone and electrospraying of TiO₂. The nanocoating compound tetrahydro-dibenzo[a,d][7]annulene-5,11-disemicarbazone synthesized in laboratory.  Nozzle   spray used for nanocoating and electrospraying techniques. The corrosion rate of aluminum was determined by weight loss method at different temperatures, concentrations and days in nitrogen dioxide medium. Potentiostat used for calculation of electrode potential, corrosion current and current density. Nanocoating and electrospraying compounds boned with base metal by chemical bonding. The bonding formation results were confirmed by activation energy, heat of adsorption, free energy, enthalpy and entropy. Thermal parameter values were obtained by Arrhenius equation, Langmuir, Frundlich and Temkin isotherm. Aluminum formed complex compound with tetrahydro-dibenzo[a,d][7]annulene-5,11-disemicarbazone and TiO₂ like Al- tetrahydro-dibenzo[a,d][7]annulene-5,11-disemicarbazone-TiO₂. These coating compounds decreased corrosion rate of aluminum and increased surface coverage area and percentage coating efficiency.

Keywords: Corrosion, nanocoating, electrospraying, nozzle spray, thermal parameters, noble composite barrier, TiO₂.