水平管喷淋式降膜蒸发及其强化的研究

本研究包括三个部分:(1)采用电加热方式研究水平管外降膜蒸发;(2)采用蒸汽加热方式研究水平管外降膜蒸发;(3)研究水平管内的蒸汽冷凝。本实验除了对光滑管进行传热研究以外,还采用多孔表面管以强化蒸发侧的传热,在管内壁插入线圈以强化冷凝侧的传热。研究结果表明,水平光滑管降膜蒸发时的传热系数比垂直光滑管以及池式沸腾管的都高得多。而多孔表面水平管的蒸发膜系数又比光滑水平管的高100～50%,其值高达40kW/m~2·℃。水平管外壁为多孔表面时,内壁附有线圈的总传热系数要比内壁为光滑面的高17%,而压力降只高20%。     

Ag掺杂对TiO2纳米薄膜结构及摩擦学性能的影响

采用溶胶凝胶法在普通载玻片上制备了TiO2和Ag/TiO2纳米结构薄膜,利用X射线衍射仪(XRD)、X光电子能谱(XPS)、原子力显微镜(AFM)及UMT-2摩擦试验机,考察了Ag掺杂量对薄膜组成结构、表面形貌及摩擦学性能的影响。实验结果表明,Ag掺杂量对TiO2薄膜表面形貌和减摩抗磨性能产生重要影响,低掺杂时Ag自润滑性能对薄膜摩擦性能的增强作用占主导,而高掺杂时其对薄膜的影响主要表现为恶化表面,从而导致摩擦性能下降。本研究测试条件下,掺杂量为5.0%(摩尔分数)时具有最佳的耐磨寿命和最低的摩擦因数。     

O.9Pb(Mg1/3Nb2/3)O3-O.1PbTiO3功能铁电薄膜的制备及其电性能研究

利用溶胶凝胶(sol-gel)技术制备Pb(Mg1/3Nb2/3)O3-PbTiO3(PMNT)铁电薄膜,研究了不同的溶剂对溶胶的配制和溶胶稳定性的影响,得到了可以长期稳定放置的溶胶;采用热重分析和差热分析的方法研究了凝胶的热解过程,确定了420℃为溶胶的热解温度,750℃为合理的结晶温度;以Pt/Ti/Si(100)为衬底,成功地制备了0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3铁电薄膜.通过X射线衍射分析了热处理温度对薄膜相的影响.通过高倍显微镜研究了薄膜的表面形态,通过ZT-Ⅱ型铁电参数测试仪对PMNT薄膜进行了铁电性能测试.测试结果表明,制备的PMNT铁电薄膜为具有完全钙钛矿相的弛豫性PMNT铁电薄膜,薄膜无裂纹,致密性好,其剩余极化和矫顽场分别可达到2.5μC/cm2和45kV/cm.     

纳米SnO2薄膜的制备及其表征

采用溶胶-凝胶法在玻璃基体表面制备纳米SnO2薄膜,通过热处理使其晶化。通过原子力显微镜(AFM)形貌分析表明,在20～80nm的粒径范围内,可通过工艺配方参数的调整人为控制SnO2薄膜的颗粒大小。通过工艺优化制得粒径为27nm左右的薄膜,薄膜颗粒较小,分布均匀,薄膜的透明性好。X射线衍射(XRD)结果表明,随着热处理温度的增加,SnO2特征峰愈来愈尖锐明显,晶体结构趋于完全。Zeta电位分析表明,添加分散剂溶胶的Zeta电位比未添加分散剂溶胶的Zeta电位高;Zeta电位越高,溶胶稳定性越好。     

脉冲偏压对PECVD制备DLC薄膜的结构及性能的影响

在不锈钢基材表面利用等离子体增强化学气相沉积技术(PECVD)改变脉冲偏压制备不同结构类金刚石薄膜(DLC)。分别采用表面轮廓仪、扫描电镜、拉曼光谱及电子探针分析薄膜的表面粗糙度、断面形貌、薄膜结构及成分,采用纳米压痕仪及划痕仪测试薄膜的纳米硬度、弹性模量和膜基结合力,采用球盘摩擦试验机测试薄膜在大气环境中的摩擦学性能。结果表明:脉冲偏压显著影响PECVD制备的DLC薄膜的表面粗糙度、微观形貌、膜基结合力、纳米硬度及摩擦学性能;随偏压的增大,DLC薄膜的表面粗糙度,摩擦因数及磨损量都先减小后增大,而膜基结合力则先增大后减小。其中2.0 k V偏压制备的DLC薄膜具有最强的膜基结合力,而1.6 k V偏压制备的DLC薄膜具有最低的表面粗糙度、最高的硬度和最优的减摩耐磨性能。     

氨基表面组装薄膜的构筑及其微观摩擦学特性

以二乙烯三胺基丙基三甲氧基硅烷(TA)作为分子底层,采用两步组装的方法在单晶硅基底表面制备一系列相同结构不同分子链长的自组装双层薄膜。利用椭圆偏光测厚仪、接触角测定仪、原子力显微镜(AFM)等对薄膜的形成及微观摩擦力进行表征。研究结果表明,低表面能的疏水性末端基团有利于降低薄膜的摩擦力和摩擦因数;组装分子碳链长度的增加有助于形成有序性强和致密度高的组装薄膜,从而减小薄膜表面的摩擦力和摩擦因数。     

基于多孔PDMS薄膜介电层的柔性压力传感器

提出一种基于多孔弹性体薄膜介电层的电容式压力传感器。该多孔弹性体薄膜是由液体相位分离原理制作而成。首先将去离子水与聚二甲基硅氧烷(PDMS)以一定比例均匀混合,随后将溶剂蒸发后形成多孔复合弹性薄膜。以ITO为电极材料,PET为柔性基底,多孔弹性体薄膜为介电层,将两电极面对面层压封装,得到电容式柔性压力传感器。由于均匀孔结构的存在,薄膜介电层在压力作用下能发生较大形变。研究结果表明,基于多孔薄膜介电层的压力传感器的灵度为0.58 kPa~(-1),具有良好的稳定性和重复性;传感器阵列能够准确地检测表面压力分布。制作的柔性压力传感器具有高灵敏度、低成本的特点,可用于人机交互界面、电子皮肤传感和细微压力变化监控等方面。     

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。     

疏水SiO2宽频增透膜的制备与研究

采用溶胶-凝胶浸渍提拉工艺在玻璃表面制备了双层增透膜,该薄膜由折射率分别为1.12和1.33的两层膜构成。薄膜在380~1 100nm和1 100~2 500nm范围内平均透过率较空白玻璃分别提高了7.68%和4.39%。薄膜接触角大约141°,且表层膜在2个月内能保持较高的疏水效果。双层增透膜制备方法简单,在宽光谱耐环境减反射领域有一定的应用潜力。     

DBD等离子体枪聚合SiOx薄膜用于金属表面防腐性能研究

用高频介质阻挡放电(DBD)等离子体枪,以六甲基二硅氧烷为单体,在大气下于铸铁表面聚合S iOx薄膜。采用红外光谱(FTIR)分析了等离子体功率对聚合膜的结构和沉积速度等影响、SEM对试样表面进行观察。实验发现铸铁表面沉积S iOx薄膜呈现致密纳米棒状交联结构,并随着厚度的增加粒子间出现团聚现象。在0.5%NaC l溶液中的腐蚀实验表明,S iOx薄膜能显著的提高铸铁的防腐性能,而通过在5%NaC l溶液中进行的动电位极化特性曲线计算得到,铸铁的腐蚀速率为4.72E-3mm/a,约为纯铸铁的1/15。     

溶胶-凝胶薄膜修饰的微结构聚合物光纤氟离子传感探头

通过对微结构聚合物光纤修饰桑色素-铝配合物掺杂的凝胶薄膜,制备了一种氟化物光纤传感探头。这种探头的结构基于微结构聚合物光纤实现,其内部具有贯穿的微孔道结构,这种微孔道结构可以作为敏感材料的载体以及微传感池。敏感层的修饰通过溶胶-凝胶过程实现,将掺有桑色素-铝的溶胶直接吸入光纤内部,可以在光纤微孔阵列中形成凝胶敏感膜。微结构光纤内部可以容纳微量液体,传感过程在微孔道内进行。基于荧光淬灭原理实现传感,氟离子对凝胶膜中桑色素-铝具有强烈的荧光淬灭作用,因此,传感探头对于不同浓度的氟离子溶液表现不同的荧光强度。在pH值为4.6的条件下,探头对于氟离子具有良好的响应,可在5～50mmol/L内传感。     

静电辅助气溶胶化学气相沉积法制备Al_2O_3薄膜

以乙酰丙酮铝为前驱体,N,N-二甲基甲酰胺为溶剂,采用静电辅助的气溶胶化学气相沉积(ESAVD)方法,在Si(100)衬底上制备了Al2O3薄膜,并采用场发射扫描电镜、能谱仪、X射线衍射仪和自动划痕仪等设备对制备的薄膜进行了表征。结果表明:采用ESAVD法制备的Al2O3薄膜平整致密而且晶粒细小,薄膜与基体之间及薄膜内部都未出现开裂现象;薄膜与基体的结合力约为5.56 N;沉积得到的薄膜为化学计量比为2∶3的氧化物薄膜;退火前的薄膜为非晶态,在1 200℃退火保温2 h后薄膜转变为-αAl2O3。     

Physical properties of ultrafast deposited micro- and nanothickness amorphous hydrogenated carbon films for medical devices and prostheses

Hydrogenated amorphous carbon films with diamond-like structures have been formed on different substrates at very low energies and temperatures by a plasma-enhanced chemical vapour deposition (PECVD) process employing acetylene as the precursor gas. The plasma source was of a cascaded arc type with argon as the carrier gas. The films grown at very high deposition rates were found to have a practical thickness limit of approximately 1.5 microm, above which delamination from the substrate occurred. Deposition on silicon (100), glass, and plastic substrates has been studied and the films characterized in terms of sp3 content, roughness, hardness, adhesion, and optical properties. Deposition rates of up to 20 nm/s have been achieved at substrate temperatures below 100 degrees C. A typical sp3 content of 60-75 per cent in the films was determined by X-ray-generated Auger electron spectroscopy (XAES). The hardness, reduced modulus, and adhesion of the films were measured using a MicroMaterials NanoTest indenter/scratch tester. Hardness was found to vary from 4 to 13 GPa depending on the admixed acetylene flow and substrate temperature. The adhesion of the film to the substrate was significantly influenced by the substrate temperature and whether an in situ d.c. cleaning was employed prior to the deposition process. The hydrogen content in the film was measured by a combination of the Fourier transformation infrared (FTIR) spectroscopy and Rutherford backscattering (RBS) techniques. From the results it is concluded that the films formed by the process described here are ideal for the coating of long-term implantable medical devices, such as prostheses, stents, invasive probes, catheters, biosensors, etc. The properties reported in this publication are comparable with good-quality films deposited by other PECVD methods. The advantages of these films are the low ion energy and temperature of deposition, ensuring that no damage is done to sensitive substrates, very high deposition rates, relatively low capital cost of the equipment required, and the ease of adjustment of plasma parameters, which facilitates film properties to be tailored according to the desired application.     

Characterization of Alq3 thin films by a near-field microwave microprobe

We observed tris-8-hydroxyquinoline aluminum (Alq3) thin films dependence on substrate heating temperatures by using a near-field microwave microprobe (NFMM) and by optical absorption at wavelengths between 200 and 900nm. The changes of absorption intensity at different substrate heating temperatures are correlated to the changes in the sheet resistance of Alq3 thin films.     

Small amplitude reciprocating wear performance of diamond-like carbon films: dependence of film composition and counterface material

Small amplitude (50 μm) reciprocating wear of hydrogen-containing diamond-like carbon (DLC) films of different compositions has been examined against silicon nitride and polymethyl-methacrylate (PMMA) counter-surfaces, and compared with the performance of an uncoated steel substrate. Three films were studied: a DLC film of conventional composition, a fluorine-containing DLC film (F-DLC), and silicon-containing DLC film. The films were deposited on steel substrates from plasmas of organic precursor gases using the Plasma Immersion Ion Implantation and Deposition (PIIID) process, which allows for the non-line-of-sight deposition of films with tailored compositions. The amplitude of the resistive frictional force during the reciprocating wear experiments was monitored in situ, and the magnitude of film damage due to wear was evaluated using optical microscopy, optical profilometry, and atomic force microscopy. Wear debris was analyzed using scanning electron microscopy and energy dispersive spectroscopy. In terms of friction, the DLC and silicon-containing DLC films performed exceptionally well, showing friction coefficients less than 0.1 for both PMMA and silicon nitride counter-surfaces. DLC and silicon-containing DLC films also showed significant reductions in transfer of PMMA compared with the uncoated steel. The softer F-DLC film performed similarly well against PMMA, but against silicon nitride, friction displayed nearly periodic variations indicative of cyclic adhesion and release of worn film material during the wear process. The results demonstrate that the PIIID films achieve the well-known advantageous performance of other DLC films, and furthermore that the film performance can be significantly affected by the addition of dopants. In addition to the well-established reduction of friction and wear that DLC films generally provide, we show here that another property, low adhesiveness with PMMA, is another significant benefit in the use of DLC films.     

Multifractal analysis of Mg-doped ZnO thin films deposited by sol–gel spin coating method

A multifractal analysis has been performed on the 3D (three-dimensional) surface microtexture of magnesium-doped zinc oxide (ZnO:Mg) thin films with doping concentration of 0, 2, 4, and 5%. Thin films were deposited onto the glass substrates via the sol–gel spin coating method. The effect of magnesium doping, on the crystal structure, morphology, and band gap for ZnO:Mg thin films has been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV–Vis spectroscopy. It has been observed that the surface of ZnO thin films is multifractal in nature. However, multifractality and complexity observed to decrease with increasing content of Mg in ZnO thin films due to formation of islands on the surface in accordance with Volmer–Weber growth mechanism. The investigations revealed that crystallinity, microtexture, morphology, and optical properties of the thin films can be tuned by controlling the Mg content within the ZnO lattice. In particular, their optical band gap energies were 3.27, 3.31, 3.34, and 3.33 eV at 0, 2, 4, and 5%, respectively. The prepared thin films of ZnO:Mg with tuned characteristics would have promising applications in optoelectronic devices.     

退火对真空蒸发Ti3O5制备光学薄膜性能的影响

采用真空蒸发法,以T i3O5为膜料分别在基片温度为200℃、250℃、300℃的条件下制备氧化钛光学薄膜,XRD结果显示,沉积态薄膜为无定形态,400℃退火后,均由无定形态向锐钛矿结构转变;不同基片温度下制备的氧化钛薄膜退火后,折射率均随基片温度的升高而增大;随着退火温度的升高,(101)晶相择优取向十分明显,结晶度增大;经过400℃、500℃、600℃退火后,薄膜折射率逐渐上升。     

反应性离化团束制备光学薄膜新技术

本文叙述了离化团束淀积光学薄膜的基本概念及特性,研制了离化团束淀积光学薄膜装置,开展了光学薄膜晶体结构与性能关系的研究。所研制的光学薄膜的牢固性相当好。基底不加温就可以得到ZnS、MgF₂的硬膜。反应性离化团束淀积的ZnO光学薄膜具有优良的织构,SiO₂光学薄膜呈现多晶结构。     

类金刚石薄膜的光学性能的研究

利用脉冲真空电弧镀的方法,在硅基底上沉积类金刚石薄膜,研究薄膜的光学性能、光学常数和离子能量关系。结果表明:不同的离子能量可以得到不同折射率的薄膜,无氢类金刚石薄膜的折射率在2.5～2.7之间变化;通过改变工艺条件来制备不同折射率的薄膜,和不同折射率的基底材料相互匹配;折射率和光学能隙随离子能量具有相反的变化趋势,和理论预测的趋势相一致;对于硅、锗等红外材料,要求的薄膜应具有1.8～2.1左右的折射率,因此提出一种基于物理汽相沉积和化学汽相沉积两种相互结合的方法,来降低薄膜的折射率,以达到和硅、锗等材料的折射率匹配。     

射频磁控溅射法制备类金刚石薄膜的研究

采用射频磁控溅射法,纯Ar溅射石墨靶,制备出了类金刚石薄膜,并对薄膜沉积速率随各工艺参数的变化规律、薄膜结构以及光学性能进行了系统的研究。结果表明,沉积速率随射频功率、CH4流量和溅射气压的增大而增大;随温度的增大呈现先增大后小的趋势。结构分析发现,所制备的DLC薄膜是由sp2键镶嵌在sp3键基体中构成的。在3μm~5μm波段对Si衬底有明显的增透效果。