Chemical interaction of Austenitic and Ferritic Steels with B4C Powder in Liquid Sodium at 600DC

M. Romedenne (1) , F. Rouillard (1) , D. Hamon (1) , M. Tabarant (1) , D. Monceau (2)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

In the framework of studies on the control rods lifetime for Sodium Fast Reactor, three commercial steels were exposed to B$_4$C powder in liquid sodium at 600DC for durations up to 3000 h. Analyses by optical and secondary electron microscopy, electron microprobe and glow discharge optical emission spectrometry revealed the formation of borides layers at the surface of the steels and slight carburization underneath. The growth of the boride layers followed parabolic kinetics. The nature of the formed boride layers was in good agreement with thermodynamic equilibrium predicted by Thermo-Calc software. The carburization depths were much lower than the ones obtained in pure carburizing sodium at 600DC. Finally, the carbon penetration depth did not grow with time revealing possible protective character of the boride layers against carbon penetration.

Keywords: Carburization; Boriding; Steels; Sodium

Domains: Nuclear Experiment [nucl-ex]; Nuclear Theory [nucl-th]

M. Romedenne, F. Rouillard, D. Hamon, M. Tabarant, D. Monceau. Chemical interaction of Austenitic and Ferritic Steels with B4C Powder in Liquid Sodium at 600DC. Corrosion, 2018, 75 (10), pp.1173-1182. ⟨10.5006/3199⟩. ⟨cea-02339815⟩