Enhancement of the effective thermal conductivity of iron oxide-coated hexagonal boron nitride/polyimide composite sheets using samarium-cobalt magnets

The orientation and distribution of the filler in hexagonal boron nitride (hBN) coated with iron oxide (Fe3O4@hBN)/polyimide (PI) composite sheets were controlled via magnetic field treatment (MFT) to enhance the effective thermal conductivity (TC) in the out-of-plane direction. Filler chain structures gradually formed in the direction of the magnetic field in the precursor solution. The effective TC of the Fe3O4@hBN/PI sheet after MFT was much higher than that of pristine hBN/PI. The effective TC of the composites was preferably improved by placing the sample near a one-sided magnet instead of in the middle of a pair of magnets. The effective TC of 10, 20, and 30 vol% Fe3O4@hBN/PI composites improved by 59%, 53%, and 35%, respectively, compared to that of pristine hBN/PI for a magnet distance of 10 mm and with the sample placed 2 mm from the bottom magnet. These values are in good agreement with those reported in the literature using MFT. The tensile strengths of the 10, 20, and 30 vol% Fe3O4@hBN/PI composites prepared using MFT were 33%, 33%, and 22% lower, respectively, than those of the composites prepared without MFT.

Automated summary

The orientation and distribution of filler in Fe3O4@hBN/PI composite sheets were controlled by magnetic field treatment (MFT) to improve the effective thermal conductivity (TC) in the out-of-plane direction. Filler chain structures aligned with the magnetic field in the precursor solution. The effective TC of Fe3O4@hBN/PI after MFT was significantly higher than that of pristine hBN/PI, especially when positioned near a one-sided magnet.