Preparation And Research Of Core-shell Structure Of Metal Nanoparticles By Arc Plasma

Core-shell structure coated with a layer of protection membrane on the surface of metal nanometer materials, not only can prevent the oxidation of the metal nanoparticles, effectively restrain the reunion of metal nanoparticles, solve metal nanoparticles in the air can’t deposit stability problem, and give the core substance of different physical and chemical properties due to the existence of the outer shell material.The unique properties of core-shell structure of nanoparticles, make core-shell nanoparticles in high density magnetic recording materials, ferrofluid, electrostatic printing, absorbing material, catalyst, nano electronic devices, environmental protection, biological medicine has wide application prospect, so the research of core-shell nanoparticles has important theoretical significance and commercial value.Firstly, this paper expounds the device of electric arc plasma method, process and mechanism; And meaningful improvements of preparing of metal nanoparticles preparation by arc plasma technology device have done. With the improvement of arc plasma device Al nanoparticle is prepared. The composition, morphology, microstructure, particle size of the nanoparticles and magnetic properties are investigated via transmission electron microscopy(TEM), selected area electron diffraction(SAED), X-ray diffraction(XRD),and energy dispersive spectrometer(EDS) and so on. The analysis show with other parameters constant to change cavity protective atmosphere, pressure and electric arc current, Al nanoparticles size as the working gas increases and the increase of molecular weight. Al nano powder production rate and particle size increases with increasing pressure and electric arc current.When the process parameters are the same and gas pressure is small, the generated aluminum nanoparticles for regular polyhedron shape or type of spherical particles; When the gas pressure is bigger, the generated products become tadpoles of nanowires.Secondly, We prepare C-coated Co nanoparticles with arc discharge plasma,With the high resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD), selected area electron diffraction(SAED) and so on testing we know that the C-coated Co nanoparticles possess clear core-shell structure, the core of the particles is Co, the surface material is C and the shell of the particles is disorder C. The average size of the nanocapsules is about51nm, the thickness of the shell is about15nm.The thermal balance-differential thermal analysis(TG-DTA) analysis shows that C-coated Co particles have good oxidation resistance. At the same time we discusses the formation mechanism of carbon-coated Co nanoparticles.Finally, the improved arc plasma equipment is used to prepared NiO-coated Ni nanoparticles, With the transmission electron microscopy (TEM), X-ray diffraction(XRD), energy dispersive spectrometry(EDS) and fourier transform infrared spectroscopy(FT-IR) testing show that the obtained nanoparticles have obvious core-shell structure. And the average size of the NiO-coated Ni nanocapsules is about44nm, the core is Ni, the shell is NiO and the thickness of shell is5～8nm. the surface of nanoparticles are bright and clean, the crystallization degree is high, and the size is small and evenly distributed. After therapeutic goods administration(TGA) and differential scanning calorimetry analysis(DTA) analysis we known that the coated nanoparticles have strong resistance to oxidation at room temperature. We use the chemical bonding mechanism to explain NiO-coated Ni nanoparticles’forming mechanism.