Chemical Papers 66 (11) 1073–1077 (2012) DOI: 10.2478/s11696-012-0202-y SHORT COMMUNICATION Corrosion of titanium diboride in molten FLiNaK (eut) Viliam Pavlík*, Miroslav Boča Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36, Bratislava, Slovakia Received 21 December 2011; Revised 28 March 2012; Accepted 29 March 2012 Pure and enriched titanium dibromide (TiB2) samples (prepared by hot isostatic pressing) with different mole ratios of Ni and Ta were investigated in contact with molten eutectic salt (FLiNaK (eut) ; LiF/NaF/KF 42.5 mole % : 11.5 mole % : 42.0 mole %) at 600 ◦ C. Corrosion resis- tance of the materials was studied, the mass losses and depths of corrosion were calculated, and sample surfaces were investigated by scanning electron microscopy-energy dispersive X-ray spec- troscopy (SEM-EDX). Nickel addition decreased the corrosion resistance of TiB2 . Simultaneous additions of both elements, Ni and Ta, as well as the addition of Ta only showed reducing effect on grain formation and they increased the corrosion resistance which is highest in the last case. c  2012 Institute of Chemistry, Slovak Academy of Sciences Keywords: molten salts, titanium diboride, corrosion, nickel addition, tantalum addition Titanium diboride (TiB 2 ) is a ceramic material and its excellent mechanical and good conductive properties predetermine its potential use in various high temperature applications especially those includ- ing highly corrosive molten salts. For example, it is considered for the use in the process of aluminium pro- duction or in Generation IV molten salts nuclear re- actors probably as a coating layer on the temperature stressed probes (A˘gao˘gulları et al., 2011; Becker & Blanks, 1984; Ett & Pessine, 1999; Jensen et al., 2008; Kaptay & Kuznetsov, 1999; Li & Li, 2007; Murthy et al., 2009; Rybakova et al., 2009; Shibuya & Ohyanagi, 2007; Sood et al., 1998). Although an eutectic mix- ture of LiF/NaF/KF (FLiNaK (eut) ; 46.5 mole % : 11.5 mole % : 42.0 mole %;) belongs to the most often used corrosion media of the molten salt family, no corrosion data considering its contact with TiB 2 are available. Mechanical properties of TiB 2 mostly depend on the preparation pathway. Several experimental tech- niques for the TiB 2 layers preparation have already been identified (Cirakoglu et al., 2000; Fang et al., 2008; Kartal et al., 2010; Peters et al., 2009; Van Me- ter et al. 1996; Wiedemann et al., 1997). Bulk or pow- dered material can be prepared by mixing of liquid fluorides or chlorides with B(III) and Ti(IV) ions con- tained in the additives of various metals (Makyta et al., 1989; Taranenko et al., 1992; Wendt et al., 1992). Ni was used by Hoke and Meyers (1996) to aid in the consolidation of combustion synthesized TiB 2 by act- ing as a high temperature lubricant with the addition of 1.5 mass %, 5 mass %, and 10 mass %. They also examined several metallic elements (Cr, Ni, Hf, Mo, Ta) suitable for the use as the matrix of TiB 2 /metal composites. Ta belongs to a group of elements with high melting temperature and it also can be used to control the grain growth of TiB 2 metal composites. Controlled mechanism of grain growth is the key process to achieve better properties. For this purpose, the TiB 2 powder was enriched with different amounts of Ni and Ta powder blended in an epicyclic mill with ZrO 2 balls and hot-isostatically pressed (Bača et al., 2011). Metal addition enabled the delimitation of grain boundaries and the control of grain growth. In this work, pure and enriched TiB 2 samples with different ratios of Ni and Ta were investigated in con- tact with molten FLiNaK (eut) . Corrosion reduction of the materials was studied, the mass losses and depths of corrosion were calculated and sample surfaces were investigated by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX). *Corresponding author, e-mail: viliam.pavlik@savba.sk