Research On The Effect Of Ultrasonic Spray Electroless Plating Process On The Structure And Properties Of CNTs/Ag Composites

With the development of our society,traditional metal materials are more and more difficult to meet the needs of people.Carbon Nanotubes are incorporated in diverse applications ranging from electrode materials,hydrogen storage and electronic devices.Carbon nanotubes reinforced silver composites(CNTs/Ag composites)are considered as a promising candidate for high-performance contact materials with the potential properties of low contact resistance,high thermal conductivity and excellent mechanical performance.While at present the dispersion of CNTs in silver matrix and the interfacial bonding of the composites remain problems to be resolved or enhanced.By coating a layer of silver,carbon nanotubes can possess strong interface with the matrixs and better dispersion in the host matrix.In traditional electroless plating,the variation in concentration is unavoidable during the plating process through direct mixing,thus gaining uniform coating layer is relatively difficult.In this study,silver nanoparticles coated carbon nanotubes(CNTs/Ag)were synthesized through an improved electroless plating method assisted by ultrasonic spray atomization,which inhibited excessive growth of silver particles and led to much more uniform nanometer grain-sized coating.In this paper,multiwalled carbon nanotubes coated with silver was successfully prepared by an ultrasonic spray electroless plating process by atomizing silver ammonia solution and the reducing solution,and reactions between liquid droplets were achieved.The possible mechanism for this process was explored preliminarily.The effect of the concention of silver ammonia solution and reaction temperature on the silver coating was studied as well.The CNTs/Ag were solution ball-milled(SBM)with Ag powders and then were densified by spark plasma sintering(SPS).The surface morphology and microstructure of silver plated carbon nanotubes were characterizated by the scanning electron microscopy(SEM),the transmission electron microscope(TEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The results showed the CNTs dispersion in Ag matrix was improved benefitting from the homogeneous Ag nanoparticles distribution on CNTs,and correspondingly,the hardness and electrical conductivity were significantly improved.The mechanism may result from the combination of more homogeneous CNTs dispersion and tighter interface bonding in composite materials.In this paper,the preparation of CNTs/Ni and composite metal plating carbon nanotubes were studied.The obtained CNTs were characterized by TEM,EDS and Raman spectra,and the results show that a continous and uniform nickel-plating layer,and the dispersion of CNTs in the product had been some improved,which made CNTs-Ni more conducive in application area of composite materials.It is found that the different microstructure of the nickel plated absorbing properties of carbon nanotubes have obvious difference.For the nickel plated CNTs with relatively thin coatings,the maximum microwave absorbing peak of the CNTs-Ni is-17.12 dB at 9.36 GHz,the band width(R<-5d B)is 5.28 GHz and the band width(R<-10dB)is 2 GHz,which is advantageous manufacturing broadband composite absorbing materials.