TY - JOUR
T1 - Synthesis of bulk nanocrystalline HfB2 from HfCl4–NaBH4–Mg ternary system
AU - Akçamlı, Nazlı
AU - Ağaoğulları, Duygu
AU - Balcı, Özge
AU - Öveçoğlu, M. Lütfi
AU - Duman, İsmail
N1 - Publisher Copyright:
© 2017, Springer Science+Business Media, LLC.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - This study reports on the synthesis and consolidation of pure HfB2 powders starting from HfCl4–NaBH4–Mg blends via autoclave processing, annealing and purification followed by pressureless sintering (PS, with 2 wt% Co aid) or spark plasma sintering (SPS). During autoclave reactions conducted at 500 °C for 12 h under autogenic pressure, excess amounts of NaBH4 were utilized to investigate its effects on the reaction products and mechanism. A subsequent washing (with distilled water), annealing (at 750, 1000 and 1700 °C) and acid leaching (HCl) were applied on the as-synthesized products. Pure HfB2 powders with an average particle size of 145 nm were obtained after autoclave synthesis in the presence of 200 wt% excess NaBH4, washing, annealing at 1000 °C for 3 h and 6 M HCl leaching. SPS sample has higher relative density and microhardness values (94.18% and 20.99 GPa, respectively) than those of PS sample (90.14% and 14.85 GPa). Relative wear resistance was improved considerably (8.2 times) by employing SPS technique.
AB - This study reports on the synthesis and consolidation of pure HfB2 powders starting from HfCl4–NaBH4–Mg blends via autoclave processing, annealing and purification followed by pressureless sintering (PS, with 2 wt% Co aid) or spark plasma sintering (SPS). During autoclave reactions conducted at 500 °C for 12 h under autogenic pressure, excess amounts of NaBH4 were utilized to investigate its effects on the reaction products and mechanism. A subsequent washing (with distilled water), annealing (at 750, 1000 and 1700 °C) and acid leaching (HCl) were applied on the as-synthesized products. Pure HfB2 powders with an average particle size of 145 nm were obtained after autoclave synthesis in the presence of 200 wt% excess NaBH4, washing, annealing at 1000 °C for 3 h and 6 M HCl leaching. SPS sample has higher relative density and microhardness values (94.18% and 20.99 GPa, respectively) than those of PS sample (90.14% and 14.85 GPa). Relative wear resistance was improved considerably (8.2 times) by employing SPS technique.
UR - http://www.scopus.com/inward/record.url?scp=85025116283&partnerID=8YFLogxK
U2 - 10.1007/s10853-017-1382-1
DO - 10.1007/s10853-017-1382-1
M3 - Article
AN - SCOPUS:85025116283
SN - 0022-2461
VL - 52
SP - 12689
EP - 12705
JO - Journal of Materials Science
JF - Journal of Materials Science
IS - 21
ER -