Studies Of Thin Films Coated On Microparticles Using Magnetron Sputtering Method

Coating thin films on powder particles can improve their application. As a kind of high quality coating method, magetron sputtering method was gradually applied to powder particles. A new magnetron sputtering equipment for coating microparticles was designed and fabricated according to the characteristic of the magnetron sputtering method and powder particles. The magnetron sputtering technology for coating metal films and metal oxide films on microparticles was systematically studied by adopting the method of combing experiment and theory, and growth mechanism of the metal film coated on particles using magnetron sputtering method was also studied in this thesis. At the same time, the applications of all kinds of metal-coated samples were investigated. This thesis mainly contains five points as follows:(1) According to the characteristic of microparticles high specific surface area and small dimensions, a new magnetron sputtering equipment for coating microparticles was designed. The sputtering equipment increases an ultrasonic vibration generator and an oscillational sample stage on the basis of the conventional direct current magnetron sputtering equipment. The experiments results showed that the equipment can keep the particles dispersing and tumbling in the deposited area during film growth and lead to each particle having the same probability of being coated. And all kinds of metal films and metal oxide films can successfully coated on various microparticles using the magnetron sputtering equipment.(2) Co, Ni, Cu and Ag films films coated on cenosphere particles using a magnetron sputtering deposition system were studied. The surface morphology, the chemical composition, the average grain size, the crystallization and the surface roughness of cenosphere particles were characterized by optical microscope (OM), field emission scanning electron microscope (FE-SEM), atomic forced microscope (AFM), inductively coupled plasma–atom emission spectrometer, x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) analysis, respectively, before and after the plating process. The results indicate that the relatively uniform, compact and adhesive metal films were successfully deposited on cenospheres through controlling the motion mode of particles during the sputter deposition. With the increasing of sputtering time or the increasing of sputtering power or the decreasing of the particle loading amount, both crystallization and grain size of metal film were improved. Estimated from FE-SEM characterizations in backscattered mode, the film thicknesses for Co, Ni, Cu and Ag films were <10, 39, 50 and 134 nm, respectively, under the same sputtering deposition conditions. This can attribute to the difference in sputtering rate for the four metals. The RMS values derived from the AFM measurements were 1.94, 4.31, 10.92 and 18.33 nm for Co, Ni, Cu and Ag films, respectively, which ascribe to the different crystallization behaviors for the four metals. Metal copper films were successfully deposited on the surface of micrometer SiC using direct current magnetron sputtering method.(3) The titania films deposited on cenosphere particles by pulse magnetron sputtering were investigated. SEM results show that the film was uniform and compact; XRD results indicate that the film was titania film and sputtering time is a importance condition to influence the films crystal. With the increasing of sputtering time, the crystallization of the titania film was improved. The titania films coated on cenospheres using magnetron sputtering method were uniform, compact and adhesive.(4) The growth mechanism of the metal film coated on cenospheres using magnetron sputtering method was also studied. The unceasingly variational relatively growth angle can eliminate the physical shadowing effect of the sputtering and promote a rather smooth, adhesive and compact film. The adatom mobility characteristic of the material and deposition conditions determines the size of the isolated island. Due to the all-around effect, the final distribution of grains shows a rather smooth morphology with low roughness and the copper films growth is a three-dimensional island growth mode.(5) The application research of the metal-coated microparticles was also investigated. The lightweighted metal-coated microparticles were first applied in the fields of shielding electromagnetic. Cu, Ni and Ag films were coated on the surface of many light materials (expanded polystyrene particles, cenosphere and lens papers) using magnetron sputtering equipment The static and dynamic attenuation capability in 3 mm wave band of different metal coated samples were studied. The static attenuation capability results indicated that the attenuation capability was better than the ultrathin electric slice, foil and chaff while its concentration is less than the ultrathin electric slice, foil and chaff. The dynamic attenuation capability results indicated that the attenuation capability of the metal coated samples in unit length is bigger than the ultrathin electric slice.