The Synthesis And Applications Of Nanostructured Boron Nitride Composites

With the rapid development of modern electronic technology and the advent of the 5G era,electronic devices tend to be lightweight,integrated and multifunctional,which poses an enormous challenge to thermal management in packaging technology.Traditional packaging materials have been unable to meet the needs of high-density packaging technology and the further development of integrated circuits.Therefore,the exploitation and utilization of new,effective thermal management materials has become one of the urgent needs in the current electronic packaging field.Hexagonal boron nitride(h-BN)with excellent thermal conductivity,high thermal stability and insulation is an ideal thermal management material with broad application prospects in the field of electronic packaging.In addition,phase change materials(PCMs)with passive thermal management for intermittent or transient heat dissipation have attracted much attention because they can provide more feasibility for thermal management of electronic equipment.However,the current common BN synthesis methods often have the disadvantages of harsh reaction conditions,high toxicity of raw materials and high cost.Phase change materials also have problems such as low thermal conductivity,poor thermal stability,high flammability and supercooling,which have caused great obstacles to their application in actual production.The main work of this paper is to investigate the synthesis of lowdimensional boron nitride nanomaterials by halide-assisted low-temperature hydrothermal method(HAHTA).This method has the advantages of simple operation,green synthesis,and high crystallinity.Then,hBNNS reinforced phase change composites were prepared and their properties were characterized.The results show that low-dimensional BN nanomaterials can be successfully prepared by the halide-assisted low-temperature hydrothermal method.By adjusting the reaction temperature and the type of halide,the phase and morphology of the obtained boron nitride can be effectively controlled.When Na F was changed to NH₄F,and the product will change from o BN nanorods to c BN nanoflowers.In particular,compared to the pure hydrothermal synthesis of boron nitride,the addition of halide can effectively increase the lateral size of hBNNS.When boric acid and ammonia are selected as raw materials at 200 ?,the well-crystallized hBNNS obtained using Na F assisted growth can reach a lateral dimension of more than 1 ?m and an average thickness of 5.1 nm,and can be in-situ functionalized,which is beneficial for further compounding application.In general,the HAHTA method as a simple and cost-effective method opens up a promising new way for the controlled synthesis of low-dimensional BN nanomaterials.Characterization of the prepared hBNNS phase change composites revealed that compared with pure phase change materials,VO₂ @ h BN composites have better oxidation resistance,and paraffin @ h BN phase change composites have high latent heat(189.0 J / g),better thermal conductivity(1.198 W / m K)and shape stability,which makes them the promising candidates in the field of electronic thermal management.