Estudo comparativo da resistência à corrosão de aços com aplicação em evaporadores

Abstract

The evaporators used in plant for sugar production are heat exchanger boxes which function are to decrease the content of water existing in the cane broth. These heat exchangers are manufactured from low corrosion resistant materials and are often substituted during the production process, making necessary extended maintenance stops and creating falls in the production. Considering the sugar and alcohol consumption increases, for internal market as for exportation, it is now necessary to look for alternative materials with higher lifetime, which means higher corrosion resistance, in order to replace materials used nowadays. The current work presents the comparative evaluation of the corrosion resistance of AISI 444 and API 5CT / ISO 11960 L80 13Cr, carbon steels ASTM A423 Gr1, AISI 1020 and API 5CT / ISO 11960 L80 Type1 and of the steels with added alloyed elements ASTM A213 GrT11 e GrT22, in environmental cane juice. Corrosion tests at high temperature, Tafel analysis and electrochemical impedance spectroscopy. The coorosion-proof steel 444 and the carbon steel 1020 showed, respectively, the best and the worst corrosion resistances in all the tests that have been performed. The other tested steels have not showed uniform results in relation with the different test methods. For the other materials, the T22 steel showed the better performance.