Pressureless consolidation of boron nitride fiber ceramics via a chemical bonding approach.

Hexagonal boron nitride (h -BN) materials with excellent physicochemical stability and processibility have been considered as promising engineering materials. However, their practical applications are rather limited by the difficulty in constructing the well-bonded h -BN ceramic. Herein, we present a reaction welding strategy for facile preparation of well-bonded h -BN fibers (BNFs) network by using ethanolamine (ETA) containing alcoholic hydroxyl and primary amine groups as crosslinking agent. The formed >B-O-H 2 C-H 2 C-H 2 N|→B< bond bridges through the esterification and intramolecular coordination (N|→B) reactions between ETA molecules and BNFs containing surface hydroxyls, play an essential role in the construction of the thermodynamically stable >B-N-B< covalent bond between BNFs. Based on this synthetic strategy and a room-temperature molding process followed by a calcination step, a series of resilient BNFs ceramics with high processibility, typical diamagnetism, low dielectric constant (∼ 2.1) and loss, good resistance to temperature different, corrosion, oxidation and abrasion are produced. Besides, they also exhibit excellent strain and damage tolerance, the maximum compression strain and strength can reach up to 38% and ∼ 33 MPa, respectively. Significantly, the deliberately designed BNFs vessel can be successfully used for the alloying of high melting point metals, showing both structural/chemical robustness and good reusability. This ingenious design for well-bonded BNFs network not only is a good model for exploring the welding way for h -BN powders, but also opens up numerous opportunities for practical applications. • A well-bonded boron nitride fibers network is prepared via chemical welding approach. • Ethanolamine (ETA) with bifunctional groups is selected as crosslinking agent. • Bond bridges are formed through esterification and intramolecular coordination reactions. • BNFs ceramics with processibility and excellent physicochemical stability are obtained. [ABSTRACT FROM AUTHOR]