磁控溅射Ni56Mn27Ga17合金薄膜的光学反射特性研究

Ni-Mn-Ga磁性形状记忆合金薄膜是非常有用的多功能材料,为考察其光学反射特性,采用磁控溅射技术在单晶硅衬底上沉积了Ni56Mn27Ga17合金薄膜,并对其表面形貌和光学反射特性进行研究。研究结果表明,薄膜的表面粗糙度随退火温度的升高而增大;在300～800nm波长范围内,薄膜反射率均随波长的减小而降低,且薄膜整体谱线范围内的反射率随退火温度的升高而降低。     

柱塞副微观表面对间隙油膜压力的影响

根据分形理论中的W-M函数建立柱塞与缸体孔表面三维形貌数学模型,并利用MATLAB软件编写程序,分析分形维数对表面微观形貌的影响。将柱塞副间隙油膜沿轴向展成平面,建立油膜厚度及压力分布计算模型,采用有限体积法求解二维雷诺方程,分析粗糙度对柱塞副间隙油膜压力分布的影响。结果表明:随着分形维数的增加,柱塞表面粗糙度呈增加趋势,且表面粗糙度越大,压力峰值越大。     

SEM and AFM studies of dip‐coated CuO nanofilms

Cupric oxide (CuO) semiconducting thin films were prepared at various copper sulfate concentrations by dip coating. The copper sulfate concentration was varied to yield films of thicknesses in the range of 445–685 nm by surface profilometer. X‐ray diffraction patterns revealed that the deposited films were polycrystalline in nature with monoclinic structure of (?111) plane. The surface morphology and topography of monoclinic‐phase CuO thin films were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Surface roughness profile was plotted using WSxM software and the estimated surface roughness was about ～19.4 nm at 30 mM molar concentration. The nanosheets shaped grains were observed by SEM and AFM studies. The stoichiometric compound formation was observed at 30 mM copper sulfate concentration prepared film by EDX. The indirect band gap energy of CuO films was increased from 1.08 to 1.20 eV with the increase of copper sulfate concentrations. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

The influence of surface topography on the photocatalytic activity of electrophoretically deposited titanium dioxide thin films

Recently, titanium dioxide thin film coatings have received considerable attention due to their wide self-cleaning abilities with applications ranging from photocatalytic building cladding to vehicle anti-fogging mirrors. Traditionally, the photocatalytic coatings are deposited by dip, spin, spray and CVD methods which are suitable for flat substrates. For irregular conductive surfaces electrochemical means such as electrophoretic deposition (EPD) can be used. In this paper, we present the use of an EPD route to alter the surface morphology of nanocrystalline TiO₂ thin films. By modifying the initial particle sizes within the colloidal suspensions used during EPD, it was possible to produce particulate coatings with differing grains sizes and surface roughness. The influence of the surface topography on the photocatalytic activity of the film was investigated through ATR-FTIR analysis of the decomposition of stearic acid under ultraviolet irradiation. It was determined that surface topography such as grain size and roughness had a key impact in the film photocatalytic properties.     

真空热处理对硫化锌薄膜光学与微结构特性的影响

针对电子束蒸发离子辅助沉积的硫化锌薄膜,研究了550℃以下真空热处理对其光学与微结构特性的影响。薄膜光学和微结构特性的测试分析表明:制备后薄膜为类立方结构的ZnS,在337.5nm波长处出现临界特性转折点,随着热处理温度的增加,转折波长两侧的消光系数变化规律相反,折射率和物理厚度呈现下降趋势,薄膜的禁带宽度逐渐增加;在红外波段的薄膜折射率与热处理温度的变化并不显著,在350℃下热处理时消光系数出现转折,主要是由晶粒变小的趋势所致;通过晶相分析,硫化锌薄膜经历了类立方结构到六方结构的转换,与禁带宽度的变化趋势基本一致。分析结果表明,光学特性变化的根本原因是薄膜的微结构特性变化。     

厚度效应对Pb(Zr0.53Ti0.47)O3薄膜微结构、铁电、介电性能的影响

用改进的溶胶-凝胶法在Pt(111)/Ti/SiO₂/Si(100)衬底上制备了不同厚度的高度(111)取向的Pb(Zr_0.53Ti_0.47)O₃薄膜.运用X射线衍射(XRD)和原子力显微镜(AFM)分析了薄膜的微结构,原子力显微镜表明厚度为0.3μm和0.56μm的PZT薄膜的晶粒尺寸和表面粗糙度分别为0.2～0.3μm、2～3μm和0.92nm、34nm.0.3μm和0.56μm PZT薄膜的剩余极化(Pr)和矫顽场(Ec)分别为32.2μC/²、79.9kV/cm, 27.7μC/cm²、54.4kV/cm;在频率100KHz时,薄膜的介电常数和介电损耗分别为539、0.066,821、0.029.     

Ag-Cu亚稳态合金薄膜的共溅射法制备及其特性研究

采用共溅射法,于不同温度下在玻璃基底上沉积Ag-Cu薄膜。X衍射(XRD)分析表明,当基片温度为100℃和200 ℃时,形成的是Ag-Cu亚稳态合金;而当温度升高到300℃以上时,形成的则是Ag和Cu的分离相。通过X光电子能谱(XPS)法测量不同温度下沉积薄膜的Ag和Cu原子含量比,发现基片加热温度对沉积元素的相对比有一定影响。原子力显微镜(AFM)检测表明,随着加热温度的升高,薄膜表面的粗糙度增加,颗粒尺寸增大。分析认为,在温度较低时,原子热激活能相对较低,不足以发生迁移,形成Ag-Cu亚稳态合金;而当温度较高时,原子热激活能增大,容易发生迁移,此时Ag和Ag、 Cu和Cu各自结合的能量最低,形成Ag和Cu的分离相。     

Al、Sn掺杂对于ZnO薄膜微结构及光学特性的影响

采用真空电子束蒸发金属薄膜及后续热氧化技术在石英衬底上分别制备出了ZnO、Al∶ZnO以及Sn∶ZnO薄膜。通过X射线衍射仪(XRD),紫外-可见分光光度计和原子力显微镜(AFM)等分析仪器对比研究了Al、Sn掺杂对ZnO薄膜结晶质量、光学性质及表面形貌的影响。测试结果表明,Al、Sn掺杂可以使薄膜结晶质量得到提高,薄膜应力部分释放,薄膜表面的粗糙度也相应增加,掺杂对薄膜光学带隙的影响在一定程度取决于金属薄膜的氧化程度,氧化充分可以使光学带隙变宽,反之则变窄。     

Influence of Mg doping on the morphology and optical properties of ZnO films for enhanced H2 sensing

Highly oriented ZnO and Mg doped ZnO thin films were fabricated on Al₂O₃ substrate by sputtering at room temperature. The effect of Mg doping on the structural, optical, and morphological properties of ZnO film was investigated. The intensity of (002) peak in X‐ray diffraction measurements revealed the influence of Mg doping on the crystallinity and orientation of ZnO film. Photoluminescence (PL) results show that the Ultraviolet (UV) emission peak was shifted to lower wavelength side for Mg:ZnO film indicating the possibility for quantum confinement. UV–vis–NIR optical absorption revealed an improvement in optical transmittance from 70 to 85%, and corresponding optical band gap from 3.25 to 3.54 eV. Atomic force microscope (AFM) images revealed the nano‐size particulate microstructure of the films. The surface topography of Mg doped ZnO film confirmed decreased grain size with large surface roughness and increased surface area, favorable for sensing. Pure ZnO and Mg doped ZnO film were used as active layer and tested for its sensing performance to hydrogen. Compared to undoped ZnO, 22 at.% Mg doped ZnO film showed much higher sensor response to H₂ at a concentration as low as 200 ppm and at a lower operating temperature of 180°C. A linear sensor response was observed for H₂ concentration in the range of 100–500 ppm. Microsc. Res. Tech. 76:1118–1124, 2013. © 2013 Wiley Periodicals, Inc.     

Film thickness and roughness of ZDDP antiwear films

The two experimental techniques, spacer layer interferometry imaging (SLIM) and atomic force microscopy (AFM), have been used to measure the thickness and roughness of zinc dialkyl dithiophosphate (ZDDP) reaction films formed in a rolling-sliding minitraction machine (MTM) tribometer. The AFM method has been complemented by a novel ZDDP film removal method based on ethylenediaminetetraacetic acid (EDTA) solution. It has been found that the two approaches measure very similar ZDDP film thickness values, lending credence to both methods. However the AFM approach measures much rougher ZDDP reaction films than MTM-SLIM and it is believed that SLIM underestimates the film roughness. Based on this, the use of MTM-SLIM is recommended for monitoring the evolution of antiwear film thickness during rubbing, while AFM should be employed for studying the morphology of antiwear films.     

Factors Influencing the Abrasion Resistance of Thin-Film Magnetic Media

Abrasion testing was performed on DC sputtered hydrogenated carbon films on commercial thin-film disks processed under several conditions. Four film characteristics were found to influence the abrasion resistance of the disk, i.e., roughness, film adhesion, carbon toughness, and coefficient of friction. It was found that both fine-scale surface topography from the sputtered layer and substrate texture degraded abrasion resistance. Excellent abrasion resistance was observed for carbon films as thin as 10 nm on polished substrates when the magnetic film topography was minimized. Film adhesion was degraded by exposure to temperature and humidity. Hydrogen incorporation into the carbon films reduced film hardness which degraded abrasion resistance.     

退火温度对二氧化钛薄膜的性能影响

为了获得性能优良的二氧化钛薄膜,采用电子束蒸发沉积方法制备二氧化钛薄膜,并分别在300、600、900℃空气中对样品进行退火处理以改善所制备二氧化钛薄膜的性能。分别采用X射线衍射(XRD)、原子力显微镜(AFM)以及分光光度计研究了退火温度对二氧化钛薄膜结构和光学性能的影响。结果表明,退火处理可以使二氧化钛薄膜由非晶态薄膜转换为金红石型薄膜,且金红石晶型成分随退火温度的加大而增大,同时退火处理可以改善二氧化钛薄膜在300~1 200nm光谱范围的总吸光率以及增大二氧化钛薄膜的应用范围。     

Atomic force microscopy imaging of polycrystalline CuInSe2 thin films

In this study, atomic force microscopy (AFM) imaging has been used to study the structural properties of polycrystalline CuInSe₂ films, which are widely used as absorber materials in thin film solar cell devices. This technique demonstrated an excellent capability for the reproducible imaging of these rough polycrystalline materials. AFM imaging in combination with statistical analysis revealed distinct differences in the structural properties (i.e. grain width and height distributions, root‐mean‐square (RMS) and peak to valley (R_(p–v)) roughness values) as a function of the specific growth technique used and the bulk composition of the films. In the case of Cu‐rich films, prepared by the H₂Se/Ar treatment of Cu/In/Cu alloys, rough surface structures were in general observed. Statistical analysis revealed two distinct distribution of grains in these samples (1.0–2.5 μm and 3–5.5 μm) with large RMS and R_(p–v) roughness values of 380 nm and 2.6 μm, respectively. In‐rich films were characterized by the presence of much smaller, roughly circular clusters with a significant reduction in both the width and height distributions as well as RMS and R_(p–v) roughness values. The most successful growth techniques, in terms of producing homogeneous and dense films, were in the cases of H₂Se/Ar treated metallic InSe/Cu/InSe alloys and the coevaporation of all materials to form CuInSe₂. Both these techniques produced absorber films with very narrow grain width and height distributions as well as small roughness values. It was possible to establish that high efficiency devices are associated with the use of absorber films with narrow width distributions between 0.5 and 2 μm and small RMS (> 300 nm) roughness values. These values are used as a figure of merit in our laboratories to evaluate the structural properties of our CuInSe₂ thin films.     

汽车用薄板的表面形貌的分形研究

本文将分形理论用于薄板表面形貌的研究上,提出了分形维数反映了表面形貌的规律性的观点。利用触针轮廓仪和数据采集系统对几种不同的毛化薄板的三维形貌进行了测量,计算了这些薄板的分形维数,并对这些薄板的表面形貌的规律性进行了讨论。     

氩气浓度对热丝法化学气相沉积纳米金刚石膜的影响

采用热丝化学气相沉积方法,以Ar+CH4+H2混合气体作为气源,通过改变氩气浓度,在单晶硅(100)基片上沉积纳米金刚石膜;采用扫描电子显微镜、原子力显微镜、X射线衍射仪和拉曼光谱仪等分析了纳米金刚石膜的形貌、微结构以及残余应力。结果表明:随着氩气浓度的增大,膜的晶粒尺寸逐渐减小到纳米级;由于晶粒细化导致膜内残余应力由拉应力变为压应力,并且压应力随氩气浓度的增大呈现先增大后减小的趋势;当氩气体积分数为98%时,即在贫氢的气氛中成功获得了平均晶粒尺寸为54 nm、均方根粗糙度约为14.7 nm的纳米金刚石膜。     

基于小波变换的三维粗糙表面分形维数计算方法

基于小波变换提出一种三维粗糙表面分形维数的计算方法。该方法采用小波变换对三维表面形貌数据进行多尺度分解,通过对不同分解尺度下小波系数平方的均值进行函数拟合,继而得到粗糙表面的三维分形维数。为验证提出的方法的正确性与准确性,采用已知参数构建三维分形表面,对不同方法下分形维数的计算结果进行对比分析。对比结果显示,相比原始盒维数法与差分盒维数法,采用提出的小波变换法计算得到的分形维数误差更小。特别是在小波变换过程中选用sym4小波基函数时,分形维数的计算误差最小,误差能够控制在2%以内。将提出的方法应用于磨削表面分形维数的计算,得到了不同粗糙度下磨削表面的分形维数,进而验证了该方法的实用性。提出的方法能够更加精确地计算三维粗糙表面的分形维数,为粗糙表面分形接触模型的构建提供了参数基础。     

类金刚石薄膜微观摩擦性能的FFM评价——针尖尺度效应

采用等离子体增强气相沉积制备了类金刚石薄膜，利用原子力显微镜的轻敲模式观察了它们的形貌，并在考虑外加载荷和扫描速度的基础上，用摩擦力显微镜（FFM）对比考察了尖端探针和平头探针对类金刚石薄膜摩擦性能评价的影响。结果表明：类金刚石薄膜的表面粗糙度随基底负偏压的增加而减小；存在于探针和类金刚石薄膜之间的水膜对尖端探针的剪切阻力贡献较大，且尖端探针测得的摩擦力变化趋势受扫描速度影响显著；水膜对平头探针起着不同形式的润滑作用，从而导致平头探针和类金刚石薄膜之间摩擦性能的速度效应存在差异；利用摩擦力显微镜考察类金刚石薄膜的摩擦性能时，存在着明显的针尖尺寸效应。     

复合氮化合物薄膜的研究

采用多源PVD技术在YG8硬质合金基体上分别沉积了Ti N和Ti NX薄膜,利用X射线衍射仪、扫描电子显微镜以及多功能材料表面试验仪,研究了多种元素的添加对Ti N涂层微观结构、断口和表面形貌的影响。结果表明:添加多种元素可使Ti N涂层的微观结构发生明显变化,能有效控制膜的结晶和生长模式,改变传统的(111)面的单一取向,从原来的(111)的择优取向,转变为(200)、(111)、(220)共同取向;Ti NX涂层的断口呈非柱状结构,表面粗糙度小于Ti N,具有更为均匀致密的结晶结构和光整的表面形貌,趋于Ti Al N薄膜的显微硬度,一致的结晶组织结构、有效的沉积效率、良好的膜基结合力有利于厚膜Ti N的制备;相对于Ti N,寿命可提高50%-100%。     

改善CVD金刚石薄膜涂层刀具性能的工艺研究

用热丝CVD法,以丙酮和氢气为碳源,在WC-Co硬质合金衬底上沉积金刚石薄膜,在分析了工艺条件(衬底温度、碳源浓度、反应压力)对金刚石薄膜性能的影响的基础上,提出了分步沉积法改善金刚石薄膜涂层刀具性能的新工艺.结果表明,合理控制工艺条件的新工艺对涂层薄膜质量、形貌和粗糙度、薄膜与衬底间的附着力、刀具的耐用度及切削性能有显著影响,对获取实用化的在硬质合金刀具基体上沉积高附着强度、低粗糙度金刚石薄膜的新技术具有重要的意义.