Desenvolvimento de um galvanostato para hidrogenação de materiais em ensaios de susceptibilidade à fragilização por hidrogênio

Abstract

This work describes the development of a galvanostat for the application of a constant current (from 1 mA to 300 mA) in an electrochemical cell, aimed to the generation of hydrogen on metallic samples that will be used in tests to evaluate the susceptibility to hydrogen embrittlement. An 8-bit microcontroller (ATmega328P) was used to generate a pulse-width modulated voltage signal, which is subsequently filtered and required to control the current applied by a galvanostat, in which the aforesaid signal is constantly monitored from the readings carried out by 10-bit A/D converter of the microcontroller. An LCD display was implemented to allow the user to visualize necessary information to configure the current to be applied, to the test monitoring and to calibrate the galvanostat. The readings of current values are indirectly made through the voltage shown on the display and a multiplicative factor defined by the selector switch (10-3, 10-2, 10-1) present on the device’s front panel. For the galvanostat validation, short and long-term tests were carried out, in which an Agilent digital multimeter, model 34410A, was used to read and acquire the currents applied between a counter-electrode and a working electrode in a given two-electrode electrochemical cell.