# Influence of SiC Polytype on the Thermal Conductivity of SiC Nanofluids: A Critical Review

## TL;DR

This paper reviews how different forms of silicon carbide affect the heat transfer properties of nanofluids, suggesting that cubic β-SiC is a promising material.

## Contribution

The paper highlights the importance of SiC polytype selection for nanofluid thermal performance and advocates for more detailed nanoparticle characterization.

## Key findings

- β-SiC has a thermal conductivity of 500 W/mK and isotropic properties, making it suitable for nanofluids.
- Using different SiC polytypes leads to inconsistent nanofluid results due to varying material properties.
- Detailed characterization of nanoparticles is essential for reliable nanofluid performance evaluation.

## Abstract

Nanofluids are suspensions of nanoparticles in a base fluid. Water, ethylene glycol, engine oil, and others are often used as base fluids, whereas inorganic additives include metals, metal oxides, carbon-based materials, and non-oxide inorganic materials. According to recent research, a small amount of nanoparticles with high thermal conductivity can improve heat transfer in nanofluids. The expectations for nanofluids are increasing, making them the subject of intense research. Current interest is focused on materials that, in addition to high thermal conductivity, also have other favorable features, such as chemical resistance or resistance to high temperatures. Silicon carbide SiC, a material with many advantageous properties, is being considered as a candidate that may meet such expectations. Among the different polymorphs of SiC, the most common are numerous hexagonal α-SiC varieties with anisotropic properties and the only isotropic cubic β-SiC polytype. The latter was reported to have a thermal conductivity of 500 W/mK. The use of nanoparticles from different SiC polytypes in nanofluid studies often leads to incomparable results. Studies on nanofluids prepared from nanoparticles of various silicon carbide polytypes discussed in this article indicate that isotropic β-SiC nanoparticles may be a promising material. When nanofluids for diverse heat transfer applications are prepared, more detailed studies of all the nanoparticles used should be considered.