Modofication Of Porous Boron Nitride Fibers By Ferromagnetic Shape Memory Alloy

Activated boron nitride?BN?materials have great potential applications in surface adsorption,such as gas,aromatic compounds,metal and all kinds of dyes,because of their thermal stability and high specific surface area.Although there are a lot of studies about synthesis methods of magnetic metal particle/BN composites and magnetic metal oxide/BN composites,but the synthetic method is not yet mature of magnetic alloy/BN composites.So in this paper,we mainly studied the synthesis methods and the influencing factors of CoNi/BN and FeCo/BN composite materials.Hydrothermal method and liquid phase reduction method were adopted for the synthesis of CoNi and FeCo alloy,then influence factors in the preparation process were studied.Characterization techniques such as Scanning Electron Microscopy?SEM?,X-ray Diffraction?XRD?and Vibrating Sample Magnetometer?VSM?were used to analyze the samples.The prepared CoNi samples had a face centered cubic structure?fcc?and high purity,their component can be controlled by the proportion of raw materials.With the increase of nickel content in the reactants,diffraction peaks intensity of the products become stronger.Besides,the reaction time and annealing temperature had great influence on the crystal structure,morphology and magnetic properties of CoNi samples.The increase of annealing temperature and reaction time can promote the crystallization of products.The synthesized FeCo samples had a body centered cubic structure?bcc?,and their particle size were between 0.5?m and 1?m.Due to magnetic interaction between the particles,some of the spherical particles are interconnected.The crystal structure and magnetic properties of FeCo samples can be controlled by the annealing temperature,the amount of reducing agent and the reaction temperature.The structure and characteristics of BN materials modified by CoNi and FeCo alloy were confirmed by XRD,FTIR,VSM and SEM.Co_xNi_1-x/BN powders with different compositions can be prepared by annealing at 800°C in the atmosphere of ammonia gas,and the prepared BN materials were adhered on the Co_x Ni_1-x-x alloy balls.Co_xNi_1-x/BN samples had high purity,so we can only observe the diffraction peaks of CoNi and BN in the XRD test results.The addition of CoNi can promote the formation of BN in the synthesis process,and the crystallization of BN phase can be controlled by annealing atmosphere and annealing time.Compared with Co_xNi_1-x alloy,the Ms of Co_xNi_1-x/BN composite samples decreased,and the Hc increased.Besides,ordered Co_xNi_1-x-x particles were disrupted,because magnetic interactions between particles weakened.The FeCo/BN samples had high purity and crystallinity,and the FeCo alloy balls were attached to the end of the BN fibers and the surface of BN broken pieces.Compared with pure FeCo alloy,the Ms of FeCo/BN composites decreased obviously,and the Hc increased.In addition,we have synthesized hexagonal boron nitride materials using ammonia borane as precursor in H2+Ar.To understand the structure and characteristics of the particles,SEM,FTIR and TEM were carried out for microstructure analysis.The lattice fringe spacing is 0.33 nm corresponding to the h-BN,and the crystal planes of?002?,?100?,?102?and?110?could be clearly identified.