Study On Preparation And Properties Of Boron Nitride Nanosphere,nanosheets And Composite Materials

BN nano-material has a lot of excellent properties,such as chemical stability,good mechanical performance,lubricity and oxidation resistance,etc.It has great application prospect in machinery,metallurgy,aerospace,electronics,optics manufacture,thermal conductive polymer materials,solid lubricating materials,energy storage materials and other fields.Based on the preparation of BN nanosphere,this paper continues to optimize its process.Meanwhile,the BN/borate and BN/borate/PS nanocomposites were synthesized by new methods.The morphology,structure,tribological properties and mechanism of nanocomposites were investiagated.In addition,we explored a new synthesis method of BN nanosheets and studied the adsorption performance.In this paper,the results are as follows.1)We improved the preparation technology of BN nanosphere.The best temperature of ammoniation is 950? and the time 30 min.The results of tests indicated that its surface is smooth and the diameter of particles is around 80~200 nm.2)The BN/borate nanocomposites were prepared using a method which the temperature of saturated solution is variable and reversed-phase microemulsion method.The experiment results shows that shell thickness of the BN/borate nanocomposites with core-shell structure is about 20~50 nm.3)The BN/PS and BN/borate /PS nanocomposites were prepared using emulsion polymerization method.The experiment results shows that PS is not easy to directly clad the BN nanosphere,howere,after the borate modification,PS can be coated on the BN nanosphere to form a new nanocomposites with core-shell structure.4)The tribological tests were performed on a four-ball tester.The results show that nanocomposites have good tribological properties.The PB value of the lubricating oil with BN/CaB4O7/PS nanocomposites is increased by 63% compare with the lubricating oil with BN nanoparticles.And the average friction coefficient of the lubricating oil with BN/CaB4O7/PS nanocomposites is reduced by 23% compare with the lubricating oil with BN nanoparticles.5)The BN nanosheets were prepared successfully using concentrated acid thermal expansion method.The results show that the size of BN nanosheets is from a few hundred nanometers to microns and their thickness is about 1~2nm.The thermal expansion mechanism is discussed.6)The adsorption performance of BN nanosheets is studied and the results show that the RhB was absorbed by BN nanosheets and the rate of adsorption is rapid.The adsorption equilibrium would achieve within 10 min and the maximum adsorption is 75.65 mg/g.Adsorption model conforms to the Langmuir model.