Synthesis of bulk nanocrystalline HfB2 from HfCl4–NaBH4–Mg ternary system

Nazlı Akçamlı; Duygu Ağaoğulları; Özge Balcı; M. Lütfi Öveçoğlu; İsmail Duman

doi:10.1007/s10853-017-1382-1

Synthesis of bulk nanocrystalline HfB₂ from HfCl₄–NaBH₄–Mg ternary system

Nazlı Akçamlı^*, Duygu Ağaoğulları, Özge Balcı, M. Lütfi Öveçoğlu, İsmail Duman

^*Corresponding author for this work

Department of Metallurgical and Materials Engineering

Research output: Contribution to journal › Article › peer-review

6 Citations (Scopus)

Abstract

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.

Original language	English
Pages (from-to)	12689-12705
Number of pages	17
Journal	Journal of Materials Science
Volume	52
Issue number	21
DOIs	https://doi.org/10.1007/s10853-017-1382-1
Publication status	Published - 1 Nov 2017

Bibliographical note

Publisher Copyright:
© 2017, Springer Science+Business Media, LLC.

Funding

This study was financially supported by “The Scientific and Technological Research Council of Turkey (TÜBİTAK)” with the Project Number of 112M470 and by “Istanbul Technical University Scientific Research Projects” with the Project Number of 37544. The authors also wish to express their appreciations to Prof. Dr. Servet Turan for his help with the SPS experiments and Prof. Dr. Hüseyin Çimenoğlu and M.Sc. Faiz Muhaffel for their supports in wear tests.

Funders	Funder number
TÜBİTAK	112M470
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu
Istanbul Teknik Üniversitesi	37544

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10.1007/s10853-017-1382-1

Cite this

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title = "Synthesis of bulk nanocrystalline HfB2 from HfCl4–NaBH4–Mg ternary system",

abstract = "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.",

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AU - Akçamlı, Nazlı

AU - Ağaoğulları, Duygu

AU - Balcı, Özge

AU - Öveçoğlu, M. Lütfi

AU - Duman, İsmail

PY - 2017/11/1

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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.

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