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


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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  1. 1

    Telle R, Sigl LS, Takagi K (2000) Boride-based hard materials. In: Riedel R (ed) Handbook of ceramic hard materials. Wiley, Weinheim, pp 802–945

    Google Scholar 

  2. 2

    Cutler RA (1991) Engineering properties of borides. In: Schneider SJ Jr (ed) Ceramics and glasses, engineered materials handbook, vol 4. ASM International, Materials Park, OH, pp 787–803

    Google Scholar 

  3. 3

    Mallik M, Kailath AJ, Ray KK, Mitra R (2012) Electrical and thermophysical properties of ZrB2 and HfB2 based composites. J Eur Ceram Soc 32:2545–2555

    Article  Google Scholar 

  4. 4

    Fahrenholtz WG, Hilmas GE, Talmy IG, Zaykoski JA (2007) Refractory diborides of zirconium and hafnium. J Am Ceram Soc 90:1347–1364

    Article  Google Scholar 

  5. 5

    Bellos A, Monteverde F, Sciti D (2006) Fast densification of ultra-high temperature ceramics by spark plasma sintering. Int J Appl Ceram Technol 3:32–40

    Article  Google Scholar 

  6. 6

    Upadhya K, Yang JM, Hoffman WP (1997) Materials for ultrahigh temperature structural applications. Am Ceram Soc Bull 76:51–56

    Google Scholar 

  7. 7

    Savino R, Fumo MDS, Silvestroni L, Sciti D (2008) Arc-jet testing on HfB2 and HfC-based ultra-high temperature ceramic materials. J Eur Ceram Soc 28:1899–1907

    Article  Google Scholar 

  8. 8

    Simonenko EP, Sevastyanov DV, Simonenko NP, Sevast’yanov VG, Kuznetsov NT (2013) Promising ultra-high-temperature ceramic materials for aero-space applications. Russ J Inorg Chem 58:1669–1693

    Article  Google Scholar 

  9. 9

    Levine SR, Opila EJ, Halbig MC, Kiser JD, Singh M, Salem JA (2002) Evaluation of ultra-high temperature ceramics for aero propulsion use. J Eur Ceram Soc 22:2757–2767

    Article  Google Scholar 

  10. 10

    Monteverde F, Bellosi A, Scatteia L (2008) Processing and properties of ultra-high temperature ceramics for space applications. Mater Sci Eng, A 485:415–421

    Article  Google Scholar 

  11. 11

    Monteverde F, Bellosi A (2005) The resistance to oxidation of an HfB2–SiC composite. J Eur Ceram Soc 25:1025–1031

    Article  Google Scholar 

  12. 12

    Monteverde F, Savino R (2007) Stability of ultra-high-temperature ZrB2–SiC ceramics under simulated atmospheric re-entry conditions. J Eur Ceram Soc 27:4797–4805

    Article  Google Scholar 

  13. 13

    Cheminant-Coatanlem P, Boulanger L, Deschanels X, Thorel A (1998) Microstructure and nanohardness of hafnium diboride after ion irradiations. J Nucl Mater 256:180–188

    Article  Google Scholar 

  14. 14

    Nasseri MM (2015) The investigation of neutron interactions with HfB2–A simulation study. Trans Indian Ceram Soc 74:177–180

    Article  Google Scholar 

  15. 15

    Choe J, Zheng Y, Lee D, Shin HC (2016) Boron-free small modular pressurized water reactor design with new burnable absorber. Int J Energy Res 40:2128–2135

    Article  Google Scholar 

  16. 16

    Rogl P, Bittermann H (2000) On the ternary system hafnium–boron–carbon. J Solid State Chem 154:257–262

    Article  Google Scholar 

  17. 17

    Guo WM, Yang ZG, Zhang GJ (2012) Synthesis of submicrometer HfB2 powder and its densification. Mater Lett 83:52–55

    Article  Google Scholar 

  18. 18

    Zhang GJ, Guo WM, Ni DW, Kan YM (2009) Ultrahigh temperature ceramics (UHTCs) based on ZrB2 and HfB2 systems: powder synthesis, densification and mechanical properties. J Phys Conf Ser 176:1–12

    Article  Google Scholar 

  19. 19

    Ni DW, Zhang GJ, Kan YM, Wang PL (2008) Synthesis of monodispersed fine hafnium diboride powders using carbo/borothermal reduction of hafnium dioxide. J Am Ceram Soc 91:2709–2712

    Article  Google Scholar 

  20. 20

    Brochu M, Gauntt B, Zimmerly T, Ayala A, Loehman R (2008) Fabrication of UHTCs by conversion of dynamically consolidated ZrB2 and HfB2 powder mixtures. J Am Ceram Soc 91:2815–2822

    Article  Google Scholar 

  21. 21

    Makarenko GN, Krushinskaya LA, Timofeeva II, Matsera VE, Vasilkovskaya MA, Uvarova IV (2015) Formation of diborides of groups IV–VI transition metals during mechanochemical synthesis. Powder Metall Met Ceram 53:514–521

    Article  Google Scholar 

  22. 22

    Blum YD, Marschall J, Hui D, Adair B, Vestel M (2008) Hafnium reactivity with boron and carbon sources under non-self propagating high-temperature synthesis conditions. J Am Ceram Soc 91:1481–1488

    Article  Google Scholar 

  23. 23

    Wang H, Lee SH, Kim HD, Oh HC (2014) Synthesis of ultrafine hafnium diboride powders using solution-based processing and spark plasma sintering. Int J Appl Ceram Technol 11:359–363

    Article  Google Scholar 

  24. 24

    Venugopal S, Boakye EE, Paul A et al (2013) Sol–gel synthesis and formation mechanism of ultra-high temperature ceramic: HfB2. J Am Ceram Soc 97:1–8

    Google Scholar 

  25. 25

    Jayaraman S, Gerbi JE, Yang Y et al (2006) HfB2 and Hf–B–N hard coatings by chemical vapor deposition. Surf Coat Technol 200:6629–6633

    Article  Google Scholar 

  26. 26

    Schwab ST, Stewart CA, Dudeck KW et al (2004) Polymeric precursors to refractory metal borides. J Mater Sci 39:6051–6055. doi:10.1023/B:JMSC.0000041701.01103.41

    Article  Google Scholar 

  27. 27

    Kuznetsov SA (2012) Electrodeposition of hafnium and hafnium-based coatings in molten salts. Chem Pap 66:511–518

    Article  Google Scholar 

  28. 28

    Kravchenko SE, Burlakova AG, Korobov II et al (2015) Preparation of hafnium diboride nanopowders in an anhydrous Na2B4O7 ionic melt. Inorg Mater 51:380–383

    Article  Google Scholar 

  29. 29

    Chen L, Gu Y, Shi L, Yang Z, Ma J, Qian Y (2004) Synthesis and oxidation of nanocrystalline HfB2. J Alloy Compd 368:353–356

    Article  Google Scholar 

  30. 30

    Akçamlı N, Ağaoğulları D, Balcı Ö, Öveçoğlu ML, Duman İ (2016) Mechanical activation-assisted autoclave processing and sintering of HfB2–HfO2 ceramic powders. Ceram Inter 42:14642–14655

    Article  Google Scholar 

  31. 31

    Chen B, Yang L, Heng H, Chen J, Zhang L, Xu L, Qian Y, Yang J (2012) Additive assisted synthesis of boride, carbide, and nitride micro/nanocrystals. J Solid State Chem 194:219–224

    Article  Google Scholar 

  32. 32

    Ağaoğulları D, Balcı Ö, Gökçe H, Duman İ, Öveçoğlu ML (2012) Synthesis of magnesium borates by mechanically activated annealing. Metall Mater Trans A 43:2520–2533

    Article  Google Scholar 

  33. 33

    Johnson JL (2010) Sintering of refractory metals. In: Fang ZZ (ed) Sintering of advanced materials: fundamentals and processes. Woodhead Publishing Limited, Cambridge, pp 356–388

    Google Scholar 

  34. 34

    Ağaoğulları D, Balcı Ö, Gökçe H, Öveçoğlu ML, Duman İ (2013) Comparative investigations of the activated sintered W-1 wt% Ni composites reinforced with various boride and oxide particles. Int J Refract Met Hard Mater 41:577–584

    Article  Google Scholar 

  35. 35

    Ağaoğulları D, Balcı Ö, Öveçoğlu ML (2017) Effect of milling type on the microstructural and mechanical properties of W–Ni–ZrC–Y2O3 composites. Ceram Inter 43:7106–7114

    Article  Google Scholar 

  36. 36

    Ağaoğulları D, Gökçe H, Duman İ, Öveçoğlu ML (2012) Influences of metallic Co and mechanical alloying on the microstructural and mechanical properties of TiB2 ceramics prepared via pressureless sintering. J Eur Ceram Soc 32:1949–1956

    Article  Google Scholar 

  37. 37

    Chaim R (2007) Densification mechanisms in spark plasma sintering of nanocrystalline ceramics. Mater Sci Eng A 443:25–32

    Article  Google Scholar 

  38. 38

    Licheri R, Orru R, Musa C, Locci AM, Cao G (2009) Spark plasma sintering of ZrB2- and HfB2-based ultra high temperature ceramics prepared by SHS. J Self-Propag High-Temp Synth 18:15–24

    Article  Google Scholar 

  39. 39

    Grashchenkov DV, Sorokin OY, Lebedeva YE, Vaganova ML (2015) Specific features of sintering of HfB2-based refractory ceramic by hybrid spark plasma sintering. Russ J Appl Chem 88:386–393

    Article  Google Scholar 

  40. 40

    Ağaoğulları D, Balcı Ö, Öveçoğlu ML, Duman İ (2011) Synthesis of α- and β-rhombohedral boron powders via gas phase thermal dissociation of boron trichloride by hydrogen. Metall Mater Trans B 42:568–574

    Article  Google Scholar 

  41. 41

    Barraud E, Begin-Colin S, Caer GL, Villieras F, Barres O (2006) Thermal decomposition of HfCl4 as a function of its hydration state. J Solid State Chem 179:1842–1851

    Article  Google Scholar 

  42. 42

    Chen L, Gu Y, Yang Z, Shi L, Ma J, Qian Y (2004) Preparation and some properties of nanocrystalline ZrB2 powders. Scripta Mater 50:959–961

    Article  Google Scholar 

  43. 43

    Zhang M, Yuan L, Wang X, Fan H, Wang X, Wu X, Wang H, Qian Y (2008) A low temperature route for the synthesis of nanocrystalline LaB6. J Solid State Chem 181:294–297

    Article  Google Scholar 

  44. 44

    Feng X, Bai YJ, Lü B, Zhao YR, Yang J, Chi JR (2004) Synthesis of nanocrystalline Ni2B via a solvo-thermal route. Inorg Chem Commun 7:189–191

    Article  Google Scholar 

  45. 45

    Chen L, Gu Y, Qian Y, Shi L, Yang Z, Ma J (2004) A facile one-step route to nanocrystalline TiB2 powders. Mater Res Bull 39:609–613

    Article  Google Scholar 

  46. 46

    Cai P, Wang H, Liu L, Zhang L (2010) Low temperature synthesis of nanocrystalline Co2B. J Ceram Soc Jpn 118:1102–1104

    Article  Google Scholar 

  47. 47

    Fang Z, Lockwood G, Griffo A (1999) A dual composite of WC–Co. Metall Mater Trans A 30:3231–3238

    Article  Google Scholar 

  48. 48

    Balcı Ö, Ağaoğulları D, Muhaffel F, Öveçoğlu ML, Çimenoğlu H, Duman İ (2016) Effect of sintering techniques on the microstructure and mechanical properties of niobium borides. J Eur Ceram Soc 36:3113–3123

    Article  Google Scholar 

  49. 49

    Silvestroni L, Sciti D (2007) Effects of MoSi2 additions on the properties of Hf- and Zr-B2 composites produced by pressureless sintering. Scripta Mater 57:165–168

    Article  Google Scholar 

  50. 50

    Einarsrud MA, Hagen E, Pettersen G, Grande T (1997) Pressureless sintering of titanium diboride with nickel, nickel boride, and iron additives. J Am Ceram Soc 80:3013–3020

    Article  Google Scholar 

  51. 51

    Hulbert DM, Jiang D, Dudina DV, Mukherjee AK (2009) The synthesis and consolidation of hard materials by spark plasma sintering. Int J Refract Met Hard Mater 27:367–375

    Article  Google Scholar 

  52. 52

    Tamburini U, Kodera Y, Gasch M, Unuvar C, Munir ZA, Ohyanagi M, Johnson SM (2006) Synthesis and characterization of dense ultra-high temperature thermal protection materials produced by field activation through spark plasma sintering (SPS): hafnium diboride. J Mater Sci 41:3097–3104. doi:10.1007/s10853-005-2457-y

    Article  Google Scholar 

  53. 53

    Sciti D, Guicciardi S, Nygren M (2008) Densification and mechanical behavior of HfC and HfB2 fabricated by spark plasma sintering. J Am Ceram Soc 91:1433–1440

    Article  Google Scholar 

  54. 54

    Sciti D, Silvestroni L, Nygren M (2008) Spark plasma sintering of Zr- and Hf-borides with decreasing amounts of MoSi2 as sintering aid. J Eur Ceram Soc 28:1287–1296

    Article  Google Scholar 

  55. 55

    Chowdhury S, Polychronopoulou K, Cloud A, Abelson JR, Polycarpou AA (2015) Nanomechanical and nanotribological behaviors of hafnium boride thin films. Thin Solid Films 595:84–91

    Article  Google Scholar 

  56. 56

    Monteverde F, Melandri C, Guicciardi S (2006) Microstructure and mechanical properties of an HfB2+30 vol% SiC composite consolidated by spark plasma sintering. Mater Chem Phys 100:513–519

    Article  Google Scholar 

  57. 57

    Tayebi N, Yanguas AG, Kumar N, Zhang Y, Abelson JR, Nishi Y, Ma Q, Rao VR (2012) Hard HfB2 tip-coatings for ultrahigh density probe-based storage. Appl Phys Lett 10:1–5

    Google Scholar 

  58. 58

    Ağaoğulları D, Balcı Ö, Öveçoğlu ML, Suryanarayana C, Duman İ (2012) Synthesis of bulk nanocrystalline samarium hexaboride. J Eur Ceram Soc 35:4121–4136

    Google Scholar 

  59. 59

    Chakraborty S, Debnath D, Mallick AR, Das PK (2014) Mechanical and thermal properties of hot pressed ZrB2 system with TiB2. Int J Refract Met Hard Mater 46:35–42

    Article  Google Scholar 

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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.

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Correspondence to Nazlı Akçamlı.

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Akçamlı, N., Ağaoğulları, D., Balcı, Ö. et al. Synthesis of bulk nanocrystalline HfB2 from HfCl4–NaBH4–Mg ternary system. J Mater Sci 52, 12689–12705 (2017).

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  • Excess NaBH4
  • Spark Plasma Sintering (SPS)
  • Autoclave Reactor
  • Pressureless Sintering (PS)
  • HfO2 Phase