Synthesis of uniform BN-coated aluminum borate nanowhiskers and their applications in reinforced magnesium matrix composites

摘要

We report on a controlled synthesis of BN tubular layers-coated aluminum borate (Al_(18)B_4O_(33)) nanowhiskers via a sol-gel and post-thermal-treatment method. A new boron source, trimethyl borate is used as a novel reactant. The Al_(18)B_4O_(33) nanowhiskers with diameters of ～20～50nm and length of ~0.5-2 μm are homogeneously sheathed over their entire lengths with thin BN tubular layers. The dependence of product morphology and structure has been investigated systematically. The pioneering studies on BN-coated Al_(18)B_4O_(33) nanowhiskers reinforced Mg matrix composites reveal that the protective BN coatings can effectively prevent the interfacial reaction between Al_(18)B_4O_(33) nanowhiskers and Mg alloys. A remarkable increase in composite hardness has been obtained by the addition of coated nanowhiskers into Mg alloys with a suitable content. The present BN-coated nanowhiskers reinforced Mg matrix composites are expected to have effective applications in aerospace community.