Next Article in Journal
Optical and Mechanical Properties of Highly Translucent Dental Zirconia
Previous Article in Journal
Native Bovine Hydroxyapatite Powder, Demineralised Bone Matrix Powder, and Purified Bone Collagen Membranes Are Efficient in Repair of Critical-Sized Rat Calvarial Defects
Article

Effect of In Situ Grown SiC Nanowires on the Pressureless Sintering of Heterophase Ceramics TaSi2-TaC-SiC

Department of Powder Metallurgy and Functional Coatings, National University of Science and Technology «MISiS», Russian Federation, Leninsky Prospect 4, Moscow 119049, Russia
*
Author to whom correspondence should be addressed.
Materials 2020, 13(15), 3394; https://doi.org/10.3390/ma13153394
Received: 4 July 2020 / Revised: 26 July 2020 / Accepted: 27 July 2020 / Published: 31 July 2020
To ascertain the influence of SiC nanowires on sintering kinetics of heterophase ceramics, two composite powders (TaSi2-TaC-SiC and TaSi2-TaC-SiC-SiCnanowire) are fabricated by mechanically activated combustion synthesis of Ta-Si-C and Ta-Si-C-(C2F4) reactive mixtures. Remarkable compressibility is achieved for the TaSi2-TaC-SiC-SiCnanowire composition (green density up to 84% as compared with 45.2% achieved for TaSi2-SiC-TaC) which is attributed to the lubricating effect of residual adsorbed fluorinated carbon (most likely C4F8). The outcomes of pressureless sintering of TaSi2-TaC-SiC and TaSi2-TaC-SiC-SiCnanowire compositions are vastly different; the former experiences no significant densification or grain growth and does not attain structural integrity, whereas the latter achieves relative density up to 93% and hardness up to 11 GPa. The SiC nanowires are not retained in consolidated ceramics, but instead, act as a sintering aid and promote densification and grain growth. Sintering mechanisms of TaSi2-TaC-SiC and TaSi2-TaC-SiC-SiCnanowire powders are analyzed using thermodynamic and ab initio grand potential calculations, as well as the analysis of grain size versus relative density relations. In the case of solid-state sintering, the densification and grain growth in heterophase non-oxide ceramics are governed by the same mechanisms as previously investigated single-phase oxides. The presence of SiC nanowires enhances grain-boundary related diffusion processes due to the high specific surface and aspect ratio of the nanowires. At 1500 °C, where the formation of the transient Si-based liquid phase is thermodynamically viable, only the SiC nanowire-containing composition demonstrated the intense grain coarsening and densification associated with liquid-assisted sintering. This effect can be attributed both to the presence of SiC nanowires and purification of residual oxide impurities due to C2F4-activated combustion synthesis employed for the in situ formation of SiC nanowires. View Full-Text
Keywords: tantalum disilicide; tantalum carbide; silicon carbide; nanowires; pressureless sintering; combustion synthesis tantalum disilicide; tantalum carbide; silicon carbide; nanowires; pressureless sintering; combustion synthesis
Show Figures

Figure 1

MDPI and ACS Style

Vorotilo, S.; Patsera, E.; Shvindina, N.; Rupasov, S.; Levashov, E. Effect of In Situ Grown SiC Nanowires on the Pressureless Sintering of Heterophase Ceramics TaSi2-TaC-SiC. Materials 2020, 13, 3394. https://doi.org/10.3390/ma13153394

AMA Style

Vorotilo S, Patsera E, Shvindina N, Rupasov S, Levashov E. Effect of In Situ Grown SiC Nanowires on the Pressureless Sintering of Heterophase Ceramics TaSi2-TaC-SiC. Materials. 2020; 13(15):3394. https://doi.org/10.3390/ma13153394

Chicago/Turabian Style

Vorotilo, Stepan, Evgeniy Patsera, Natalya Shvindina, Sergei Rupasov, and Evgeniy Levashov. 2020. "Effect of In Situ Grown SiC Nanowires on the Pressureless Sintering of Heterophase Ceramics TaSi2-TaC-SiC" Materials 13, no. 15: 3394. https://doi.org/10.3390/ma13153394

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop