Thermogravimetry and acoustic emission in situ. An innovative solution for corrosion studies of metals and alloys at high temperatures
Apport d’un couplage innovant : l'émission acoustique associée à la thermogravimétrie, pour la compréhension de la corrosion des métaux et alliages à haute température.
Résumé
Context:
¤ Catastrophic oxidation of Zr alloy in oxidant atmosphere (detrimental effect of nitrogen) → 700°C-900°C (accidental conditions in nuclear plants)
¤ Catastrophic corrosion by metal dusting of Fe-based or Ni-based alloys in reducing environment with high carbon activity (ac > 1) → 400°C-700°C (petro-chemical or chemical plants)
→ Anticipate the breakage and life time prevision of material
→ In line monitoring of facilities with acoustic emission (EA)
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Method combining acoustic emission and thermogravimetry for an improved evaluation of the high temperature corrosion
Summary:
1-TGA- in situ Acoustic Emission
High-temperature corrosion
Innovative solution : TGA + EA in situ
2-Oxidation of Zy 4
Test at high temperature : Zirconium alloy oxidation
Oxygen /Nitrogen tests : Zircalloy 4
Rate of mass gain as a function of time
Bursts average frequency variation as a function of time blank test (▲) Zircaloy-4 oxidation air test (●)
Rate of mass gain and burst amplitude as a function of time
Raman microscope (HORIBA JOBIN YVON -XPLORA)
Pure oxygen tests : Zircalloy 4
AE signals recorded during cooling
Typical AE burst waveform continuous wavelets
Heat Flow variation as a function of temperature during cooling
3-Fe Metal dusting
Metal dusting : iron at 650 °C
Metal dusting : pre-oxidized iron at 650 °C
Rate of mass gain of pre-oxidized iron at 650 °C
Burst amplitude as a function of time
Oxidation of Fe (20min)
Oxidation of Fe (5min)
Mechanism (Metal dusting of pre-oxidized iron )
4-Conclusion
5-Developments