Surface Modification of Boron Nitride Nanosheets for Effective Heat Transfer Applications

Boron Nitride Nanosheets (BNNS) were modified with stearic acid (SA) and dispersed in a heat transfer oil, Thermic fluid-32 (T/F-32). SA is a good surface modifier and its amphiphilic nature provide better compatibility between the liquid - solid phase. SA consist of hydrophobic tail portion, long chain hydro carbon and a hydrophilic polar head group. The surface modification of BNNS with SA helps to improve the compatibility of the BNNS with the base fluid. The amphiphilic character of SA improves the modified BNNS's dispersion stability in fluids. The modified samples were subjected to Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Raman Spectroscopy and Scanning Electron Microscope (SEM). The nanofluid was found to be stable even after a week, which signifies the excellent dispersion stability of the nanofluid and was verified using UV analysis. The effect of SA modified BNNS/T/F-32 nanofluid on thermal conductivity and viscosity was studied in detail. An enhancement in thermal conductivity of 10% was achieved for 3 wt% SA modified BNNS/T/F-32. In addition, the results show that stearic acid is a good surface modifier for BNNS to achieve better dispersion for nanofluid applications.