【作者】 俞晓正；

【导师】 沈志刚；

【作者基本信息】 北京航空航天大学 ， 工程力学， 2008， 博士

【摘要】 在粉体颗粒表面镀薄膜可显著增强其应用功效。磁控溅射沉积作为一种高质量的镀膜方法,也逐渐被应用于粉体颗粒表面镀膜。本论文根据磁控溅射及粉体颗粒的特点,设计并研制了一套微颗粒磁控溅射镀膜设备;采用实验与理论分析相结合的方法,对在粉体颗粒表面磁控溅射镀金属薄膜和氧化物薄膜进行了系统的实验研究,并对粉体颗粒表面磁控溅射镀膜的机理进行了研究;同时还对微颗粒表面镀金属膜的应用进行了研究。主要研究工作包括如下五个方面:(1)根据微颗粒具有比表面积和表面能较大、颗粒之间易团聚、曲率半径小的特点,设计研制了一套微颗粒表面磁控溅射镀膜设备,该设备是在普通磁控溅射镀膜设备的基础上,增加了一个既可振动又可摇摆的样品台。实验结果表明,该设备能使微颗粒保持较好的分散性和流动性,使微颗粒可以等概率地暴露在溅射束流中,从而达到了在微颗粒表面高质量镀膜的目的。(2)利用磁控溅射方法,开展了在空心微珠表面镀金属Ag、Cu、Ni和Co膜的实验研究。通过光学显微镜(OM)、扫描电镜(SEM)、X射线能谱仪(EDS)、透射电镜(TEM)、电感耦合等离子体原子发射光谱仪(ICP)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)和原子力显微镜(AFM)等测试仪器,对空心微珠表面金属膜的表面形貌、表面成分、微结构及表面粗糙度进行了测试和分析。结果表明:所镀的空心微珠表面金属膜具有均匀性好、纯度高、致密性高及附着力强等特点。不同溅射条件对金属薄膜质量(表面形貌、厚度、表面粗糙度及结晶)有着直接的影响。溅射时间越长或溅射功率越大或装载量越少,薄膜的平均厚度越厚,薄膜表面越粗糙,金属薄膜的结晶度就越高。由于金属Ag、Cu、Ni和Co的溅射率的差异(YAg>YCu> YNi> YCo),在相同溅射条件下,制备的四种不同金属膜具有不同的厚度,其表面粗糙度也不同,它们的增长趋势与溅射率的增长相同。同时,用磁控溅射方法,也成功地在SiC微颗粒表面镀上了金属铜膜。(3)利用脉冲磁控溅射方法,开展了在空心微珠表面镀TiO2薄膜的实验研究。SEM结果表明,薄膜表面均匀致密;XPS结果表明,Ti元素主要以Ti4+存在,这说明空心微珠表面已成功地镀覆上了TiO2薄膜;XRD结果表明,溅射时间对TiO2薄膜的结晶有着重要的影响,溅射时间越长,TiO2薄膜越容易结晶。该方法所制备的二氧化钛薄膜有较高的均匀性和附着力。(4)开展了磁控溅射对空心微珠表面金属薄膜的沉积机理研究。研究结果表明:溅射原子不断变化的相对沉积角度,可以消除普通溅射镀膜所引起的物理阴影效应,同时可以促进均匀性好、致密性高、孔隙率低及粗糙度值小的薄膜的生成。薄膜的溅射条件及吸附原子的迁移特性决定了沉积岛的尺寸。在薄膜生长的最后阶段,由于各方面因素的综合影响,空心微珠表面获得了具有较低粗糙度的均匀金属膜,但其生长方式仍为三维岛状生长模式。(5)开展了对微颗粒表面镀金属薄膜的应用研究。提出了把表面镀金属膜的轻质微颗粒用于屏蔽和干扰电磁波的设想。利用微颗粒磁控溅射镀膜设备,在直径为1~3mm的发泡聚苯乙烯(EPS)颗粒和轻质擦镜纸表面镀金属铜、镍和银薄膜。把镀膜样品进行3mm电磁波的静态和动态衰减试验研究。静态衰减试验表明:镀金属膜EPS、镀金属膜擦镜纸及镀金属膜空心微珠,对3mm电磁波的静态衰减效果都要好于超薄导电片和箔条。动态衰减试验表明:在浓度相近的情况下,镀铜膜擦镜纸、镀铜膜EPS颗粒和镀镍膜EPS颗粒样品对3mm电磁波单位长度的衰减分贝数都要大于超薄导电片。更多还原

【Abstract】 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.更多还原