Nickel ferrite (NiFe2O4): A possible candidate material as reference electrode for corrosion monitoring of steel in concrete environments

Nickel ferrite (NiFe2O4) was tried first time as a possible candidate material as embeddable reference sensor in concrete environments. NiFe2O4 was synthesized in the laboratory and assembled reference cell which consists of three compartments. The sensor performance was evaluated in concrete environments such as saturated calcium hydroxide solution, synthetic concrete pore solution and ordinary Portland cement (OPC) extract. The consistency test and electrochemical stability test of the sensor were studied in the said concrete environments and the half cell potential was found to be −300 mV vs. SCE. The reversibility of sensor in the three alkaline solutions was found to be within ±5 mV, which was very well within the limit as sensor material for concrete. The polarization and impedance tests of NiFe2O4 sensor in concrete environments showed the stability of the sensor material in the highly alkaline concrete environments.