  A three-dimensionally interconnected hexagonal boron nitride (3Di-hBN)
networked Cu-Ni (3Di-hBN-Cu-Ni) composite was successfully synthesized in situ
using a simple two-step process which involved the compaction of mixed Cu-Ni
powders (70 wt.% Cu and 30 wt.% Ni) into a disc followed by metal-organic
chemical vapor deposition (MOCVD) process at 1000{\deg}C. During MOCVD, the
Cu-Ni alloy grains acted as a template for the growth of hexagonal boron
nitride (hBN) while decaborane and ammonia were used as precursors for boron
and nitrogen, respectively. Boron and nitrogen atoms diffused into the Cu-Ni
solution during the MOCVD process, precipitated out and grew along the Cu-Ni
interfaces upon cooling. It was demonstrated that pores were generated during
the sintering process and then filled by bulk hBN during the MOCVD process
(indicated by energy dispersive spectroscopy) as the pores also served as
catalytic sites for the nucleation and growth of hBN. Optical microscopy
examination indicated that there was a minimum amount of bulk hBN at certain
compaction pressure (280 MPa) and sintering time (30 min). Scanning electron
microscopy and transmission electron microscopy revealed that the
interconnected network of hBN layers surrounding the Cu-Ni grains was developed
in the 3Di-hBN-Cu-Ni composite. This 3Di-hBN network is expected to enhance the
resistance of the 3Di-hBN-Cu-Ni composite against mechanical, thermal and
chemical attacks. Moreover, foam-like 3Di-hBN was extracted from 3Di-hBN-Cu-Ni
composite which could be further applied in the fields of biomedicine and
energy storage.
