In situ synthesis of B4C–SiC, B4C–TiB2, and B4C–ZrB2 composites from organic–inorganic hybrid precursor via a simple bottom-up approach

• Published in: Journal of sol-gel science and technology Vol. 92; no. 3; pp. 745 - 759
• Main Authors: Parlakyigit, Abdullah Selim, Ergun, Celaletdin
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-12-2019; Springer Nature B.V
• Subjects: Argon; Boron; Boron carbide; Boron oxides; Carbon; Ceramics; Chemistry and Materials Science; colloids; Composites; Composition; etc.; fibers; Gas flow; Glass; Heat treatment; Hexagonal lattice; Inorganic Chemistry; Lattice parameters; Materials Science; Molecular composites; Morphology; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper: Nano-structured materials (particles; Particle size distribution; Particulate composites; Precursors; Refractory materials; Silicon carbide; Sucrose; Synthesis; Titanium diboride; Zirconium compounds; Zirconium diboride; Silicon carbide; Bottom-up approach; Titanium diboride; Boron carbide; In situ composite
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-019-05143-8

Boron carbide (B
4
C) and its in situ composites were synthesized via a simple bottom-up process using low-cost boric acid and a sucrose-based precursor solution with silicon (Si), titanium (Ti), or zirconium (Zr) species. The precursor solution was first dried at 250 °C and then heat-treated at 1650 °C for 90 min under argon and hydrogen gas flow. Free boron oxide phases appeared in the boric acid-rich precursor compositions, whereas free carbon appeared in the sucrose-rich compositions. The B
4
C particles exhibited a coarser and elongated morphology with boron-rich stoichiometric compositions (B/C:4/1), whereas the particles had a finer equiaxed morphology in carbon-rich compositions (B/C:2/1). As the carbon concentration increased in the precursor solution, the hexagonal lattice parameters of B
4
C and its corresponding lattice volume decreased. On the other hand, the addition of Si, Ti, or Zr species into the precursor solution resulted in the formation of a silicon carbide (SiC), a titanium diboride (TiB
2
), or a zirconium diboride (ZrB
2
) phase along with the B
4
C phase and was associated with an overall reduction in the average particle size and a more uniform size distribution. Moreover, the addition of these species increased the B
4
C lattice parameter with a corresponding increase in the lattice volume; this was most likely due to an elemental substitution into the B
4
C lattice. In addition, the data provide evidence that the formation of an ideal B
4
C lattice is possible when synthesized from carbon-rich precursors using this method, despite the potential presence of free carbon.
Highlights
Synthesis of pure B
4
C and in-situ composites of B
4
C–SiC, B
4
C–TiB
2
, and B
4
C–ZrB
2
from organic–inorganic hybrid precursor.
Effects of C content and addition of Si, Ti, and Zr species on the morphology of different kinds of ceramic particles.
Obtainment of standard B
4
C structure (JCPDS #35-0798) in C-rich precursor.
The changes in lattice parameters of B
4
C depending on B/C ratio and Si, Ti, and Zr contents in precursor solution.