Key issues on the reactive sintering of ZrB2 ceramics from elementary raw materials

Zou, Ji; Ma, Hao; Chen, Lei; Wang, Yujin; Zhang, Guojun

doi:10.1016/j.scriptamat.2019.01.044

Cited by 17 publications

(4 citation statements)

References 23 publications

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“…Previous studies of RHP ZrB 2 have all observed residual ZrO 2 present in the microstructure. [16][17][18][19][20][21]23,24 Chamberlain et al 16 and Lonergan et al 9 both reported approximately 2 vol% residual ZrO 2 in their dense ceramics. Borothermal and carbothermal reduction have been previously demonstrated as effective at removing oxide species from commercial ZrB 2 powders, and in the production of low-oxygen ZrB 2 powders.…”

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confidence: 97%

“…[16][17][18][19][20][21][22] This reduction in processing temperature has been attributed to minimizing oxygen impurities, and the formation of nano-crystalline ZrB 2 from the in-situ reaction. [16][17][18][19][20][21]23,24 Chamberlain et al 16 and Lonergan et al 9 both reported approximately 2 vol% residual ZrO 2 in their dense ceramics. Thus, minimizing oxygen content may improve densification.…”

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confidence: 99%

“…temperatures as low as 1800°C, more than 300°C less than conventional hot pressing of commercial powders without additives. [16][17][18][19][20][21][22] This reduction in processing temperature has been attributed to minimizing oxygen impurities, and the formation of nano-crystalline ZrB 2 from the in-situ reaction. Oxygen impurities (typically present on particle surfaces as ZrO 2 and B 2 O 3 ) are thought to promote coarsening and inhibit densification in diboride ceramics.…”

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Microstructure and mechanical properties of reaction‐hot‐pressed zirconium diboride based ceramics

Neuman

Fahrenholtz

2019

Int J Applied Ceramic Tech

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ZrB2 ceramics were prepared by in‐situ reaction hot pressing of ZrH2 and B. Additions of carbon and excess boron were used to react with and remove the residual oxygen present in the starting powders. Additions of tungsten were utilized to make a ZrB2‐4 mol%W ceramic, while a change in the B/C ratio was used to produce a ZrB2‐10 vol% ZrC ceramic. All three compositions reached near full density. The baseline ZrB2 and ZrB2–ZrC composition contained a residual oxide phase and ZrC inclusions, while the W‐doped composition contained residual carbon and a phase that contained tungsten and boron. All three compositions exhibited similar values for flexure strength (~520 MPa), Vickers hardness (~15 GPa), and elastic modulus (~500 to 540 GPa). Fracture toughness was about 2.6 MPa m1/2 for the W‐doped ZrB2 compared to about 3.8 MPa m½ for the ZrB2 and ZrB2–ZrC ceramics. This decrease in fracture toughness was accompanied by an observed absence of crack deflection in the W‐doped ZrB2 compared with the other compositions. The study demonstrated that reaction‐hot‐pressing can be used to fabricate ZrB2 based ceramics containing solid solution additives or second phases with comparable mechanical properties.

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Microstructure and mechanical properties of reaction‐hot‐pressed zirconium diboride based ceramics

Neuman

Fahrenholtz

2019

Int J Applied Ceramic Tech

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“…UHTCMCs are based on a dense-matrix of borides, carbides or nitrides such as ZrB 2 , HfB 2 , ZrC, HfC, TaC, HfN, and carbon fiber reinforcement (C f ). The former is characterized by high melting points, high hardness, chemical inertness and relatively good resistance to oxidation in severe environments [4][5][6][7]. The latter should enhance the damage tolerance and thermal shock resistance [8].…”

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confidence: 99%