Boron doping induced thermal conductivity enhancement of water-based 3C-Si(B)C nanofluids

Abstract

In this paper, the fabrication and thermal conductivity (TC) of
water-based nanofluids using boron (B)-doped SiC as dispersions are
reported. Doping B into the β-SiC phase leads to the shrinkage of
the SiC lattice due to the substitution of Si atoms (0.134 nm radius)
by smaller B atoms (0.095 nm radius). The presence of B in the SiC phase
also promotes crystallization and grain growth of obtained particles.
The tailored crystal structure and morphology of B-doped SiC
nanoparticles are beneficial for the TC improvement of the nanofluids by
using them as dispersions. Using B-doped SiC nanoparticles as
dispersions for nanofluids, a remarkable improvement in stability was
achieved in SiC-B6 nanofluid at pH 11 by means of the Zeta potential
measurement. By dispersing B-doped SiC nanoparticles in water-based
fluids, the TC of the as-prepared nanofluids containing only 0.3 vol.%
SiC-B6 nanoparticles is remarkably raised to 39.3% at 30 °C compared to
the base fluids, and is further enhanced with the increased temperature.
The main reasons for the improvement in TC of SiC-B6 nanofluids are
more stable dispersion and intensive charge ions vibration around the
surface of nanoparticles as well as the enhanced TC of the SiC-B
dispersions.