Wet-jet milling-assisted exfoliation of h-BN particles with lamination structure

The ability to exfoliate hexagonal boron nitride (h-BN) as laminated particles has been discussed by various mechanical high shear devices, such as vortex fluid (VF), planetary homogenizer(PH), ultrasonication (US) and wet-jet milling (WJM) with effective shear flow. The sedimentation test showed that the height of sediment of h-BN prepared by WJM was much higher than that of h-BN prepared by other mechanical methods, indicating that WJM process led to exfoliation of the laminated h-BN effectively. Also, the particle size distributions showed that the particle size of wet-jet milled h-BN was as similar as the initial particle size, whereas the particle sizes of h-BN prepared by other mechanical devices were less than 70% of the initial particle size. These results suggested that the difference of particle size after mechanical methods were based on the method of applying shearing force on the mechanical methods. In the mechanical methods such as VF, PH and US, the exfoliated h-BN would be destroyed even if the exfoliation of h-BN was progressed. On the other hand, in the case of the WJM, h-BN must be uniformly aligned in the thickness direction by pushing the slurry out at a high pressure, and the large impact energy is applied in the direction of the thickness of the h-BN particles. Therefore, it was found that the exfoliation of h-BN progressed by WJM was effective.