A NEW METHOD FOR THE MEASUREMENT OF THE DIFFUSIVITY OF CARBON IN ALPHA-IRON USING AN ELECTROCHEMICAL-CELL

A new method has been employed to measure the diffusivity of carbon in alpha iron, The method involves the measurement of ionic current of a carbon concentration cell which employs an iron cylinder as the anode . The design of the cell is such that when a constant external potenti al is applied, the ionic current is determined by the concentration po larization of carbon in the two electrodes. From the values of ionic c urrent, the diffusivity of carbon (D-c) is calculated by the applicati on of Fick's law. The results in the temperature range 854-975 K have been fitted by regression analysis to obtain the expression: D-c = 2.4 48 x 10(-5) exp(-102900.7/RT) with D-c in m(2) s(-1) and R in JK(-1) m ol(-1). The results agree well with data in the literature.