Solution‐Based Synthesis of Submicrometer ZrB₂ and ZrB₂–TaB₂

Abstract

Zirconium diboride and a zirconium diboride/tantalum diboride mixture were synthesized by solution‐based processing. Zirconium n‐propoxide was refluxed with 2,4‐pentanedione to form zirconium diketonate. This compound hydrolyzed in a controllable fashion to form a zirconia precursor. Boria and carbon precursors were formed via solution additions of phenol–formaldehyde and boric acid, respectively. Tantalum oxide precursors were formed similarly as zirconia precursors, in which tantalum ethoxide was used. Solutions were concentrated, dried, pyrolyzed (800°–1100°C, 2 h, flowing argon), and exposed to carbothermal reduction heat treatments (1150°–1800°C, 2 h, flowing argon). Spherical particles of 200–600 nm for pure ZrB2 and ZrB2–TaB2 mixtures were formed.

Low Temperature Carbothermal Reduction Synthesis of ZrC Nanofibers via Cyclized Electrospun PVP/Zr(OPr)4 Hybrid

“…Considering the increase of carbon contents in the final heat‐treated fibers with increasing the C/Zr ratio of as‐spun fibers from 4 to 7, the same C/Zr = 5.5 ratio was kept for all the samples to produce stoichiometric ZrC according to literatures . A total of 1.86 mL zirconium n‐propoxide was modified with 0.5 mL acetic acid and 1.27 mL acetylacetone at 60°C to form chelating ligand of Zr(OPr) 2 (OAc) 2 and Zr(OPr) 4‐x (acac) x under continuous stirring as shown in Eqs (1,2), respectively …”

“…However, zirconium alkoxides used in solgel procedure are extremely exposed to hydrolysis and pyrolysis. Accordingly, the precursors such as zirconium n‐propoxide (Zr(OPr) 4 ) to better workability are chemically modified in situ by chelating agents such as acetylacetone (acac) and acetic acid (AcOH) …”

Synthesis of ultrafine ZrB2 powders by sol-gel process

“…The most important advantage of solution-based synthesis is that more uniform mixing of components (atomic-scale or molecular-scale mixing) can be achieved, and ultrafine powders could be synthesized [7].…”

Polymer precursor‐derived HfC–SiC ultrahigh‐temperature ceramic nanocomposites

“…Due to the high melting point (3890°C), low oxygen diffusion coefficient, and high phase stability etc, Hafnium carbides (HfC) has been considered as a promising candidate for extreme application such as leading edges for hypersonic vehicles, diffusion barrier in nuclear industry, etc . Commonly, HfC has to be synthesized by inorganic sintering because no resource is present in the natural world.…”