Silicothermic synthesis of phase‐pure HfB₂ fine powder

Abstract

Phase pure and nano-sized hafnium diboride (HfB 2) fine powder was prepared via a novel sustainable silicothermic route at 1100°C from inexpensive raw materials HfO 2 , Na 2 B 4 O 7 and Si. By introducing sodium oxysalts as source of Na 2 O into the batch mixtures, the SiO 2 / Na 2 O modulus in the melt were reduced from

Low temperature controllable synthesis of transition metal and rare earth borides mediated by molten salt

“…The synthesis process was very similar to that in the MSM-MRS of ZrB 2 , although in this case, a slightly higher temperature of 1100 °C was required to complete the synthesis reaction and obtain phase pure HfB 2 . 132 But the particle size of the resultant HfB 2 was much smaller (about 200 nm). 132 In addition to Mg and Si, Al could be another good reductant for MSM-MRS. By using it as a reductant, Velashjerdia et al synthesised ZrB 2 platelets in a KCl-NaCl or NaF-KF eutectic salt at a much lowered temperature (800 °C).…”

“…132 But the particle size of the resultant HfB 2 was much smaller (about 200 nm). 132 In addition to Mg and Si, Al could be another good reductant for MSM-MRS. By using it as a reductant, Velashjerdia et al synthesised ZrB 2 platelets in a KCl-NaCl or NaF-KF eutectic salt at a much lowered temperature (800 °C). The process was found to be controlled by the 'dissolution-precipitation' mechanism.…”

“…The synthesis process was very similar to that in the MSM-MRS of ZrB 2 , although in this case, a slightly higher temperature of 1100 °C was required to complete the synthesis reaction and obtain phase pure HfB 2 . 132 But the particle size of the resultant HfB 2 was much smaller (about 200 nm). 132…”