Destruction, amorphization and reactivity of nano-BN under ball milling

Abstract

a b s t r a c tThe processes of mechanical activation of a hexagonal boron nitride (h-BN) and its reactivity upon interaction with hydrogen and water were investigated using X-ray, TEM, Microdiffraction, Dynamic Light Scattering, FTIR-spectroscopy, adsorption (BET). Initial h-BN samples were monocrystalline plates 70-80 nm thick. Mechanical treatment of h-BN is accompanied by plate splitting and formation of crystallographically oriented "rods." The rod thickness gradually diminishes to less than 5 nm. Specific surface area of the rods (400 m 2 /g), is found to be equal to the outer geometrical surface of rods. As nanocrystallites form "c" parameter of h-BN increases. When nanocrystallites are less than several nanometers in size, mechanical treatment results in BN amorphization; in this case specific surface of the system begins to decrease. Splitting of BN plates in the atmosphere of hydrogen is accompanied by the material hydrogenation and formation of B H and N H bonds. The amount of adsorbed hydrogen corresponds to monolayer filling. The amorphous part of activated BN interacts with water even at room temperature.

Solid‐state shear milling method to prepare PA12/boron nitride thermal conductive composite powders and their selective laser sintering 3D‐printing

“…With the increase of the BN content from 0 to 40 wt % (0 means pure PA12), the corresponding particle size shifts toward the low‐particle‐size direction (from pure PA12 28‐400 μm to PA12/BN [40 wt %] 10‐260 μm), indicating that the incorporation of BN filler particles is beneficial to the reduction in particle size of polymer PA12. Consequently, the rigid h‐BN particles incorporated show the significant effect of grinding‐aid agent on the pulverization of PA12 by effectively cutting the flexible PA12 particles like a sharp blade . Besides, Figure (b) shows the particle size distribution of PA12/BN (40 wt %) system.…”

“…Consequently, the rigid h-BN particles incorporated show the significant effect of grinding-aid agent on the pulverization of PA12 by effectively cutting the flexible PA12 particles like a sharp blade. 31,32 Besides, Figure 3(b) shows the particle size distribution of PA12/BN (40 wt %) system. Obviously, it can be seen that the size of PA12/BN (40 wt %) copowder prepared via S 3 MCP method ranges from 10 to 260 μm.…”

Mechanochemistry of hexagonal boron nitride: 1. Destruction and amorphization during mechanical treatment

“…Despite the high interest in the possibilities of using mechanically activated BN and its mixtures, the regu larities of the mechanical activation of boron nitride and its reactivity have been poorly studied. The data on the mechanical activation of h BN were first obtained in [5,9,[16][17][18][19]. It was shown that the sizes of CSR decreased, the interlayer distance d(002) increased, and various defects arose in the material.…”

“…It was shown that the sizes of CSR decreased, the interlayer distance d(002) increased, and various defects arose in the material. A question remains being debatable whether the amor phous state is reached during the mechanical activa tion of h BN [5,19] or the defective structure is con fined to a nanocrystalline state [16].…”

“…Initial h BN samples (a purity of 99%) were single crystal pellets with diameters of 300-500 nm, thick nesses of 70-80 nm, and a specific surface area of 12 m 2 /g (for details, see [19]).…”