Suivi de la corrosion d'alliages par thermogravimétrie couplée à l'émission acoustique/Thermogravimetric experiments coupled with acoustic emission analysis dedicated to high-temperature corrosion studies of alloys

Abstract

National audienceThe high temperature corrosion of alloys in petrochemical equipments can create stresses in the materials. The relaxation of these stresses mostly produces transient elastic waves which can be considered as acoustic emission. Several methods allow to record and analyze these transient elastic waves. In high temperature environments waveguide are used to transmit elastic waves from the sample to piezoelectric sensors fixed in a cold part of the equipment. The waveguide (WG) design is optimized to record an important number of waves with a low attenuation of energy and frequency signal. Alumina is often used as waveguide; this material conserves the waveform which is specific to one type of stresses. The aim of our study is to associate the elastic waves to the corrosion phenomena in order to be able to monitor the industrial equipment using acoustic emission method. For this purpose a laboratory study was launched using thermogravimetric analysis (TGA) coupled with acoustic emission devices to measure acoustic signals emitted during the corrosion of samples at high temperature. Simultaneous measurements of the mass variation and of the acoustic signals can give complementary information to increase the level of understanding of high temperature corrosion mechanisms and their monitoring. This work focuses on the implementation of an alumina waveguide in a TGA apparatus and on high temperature validation tests of waves' transmission based on experiments dedicated to the oxidation of zirconium alloy plates