外加电场对云母表面纳尺度摩擦行为的影响

利用原子力显微镜(AFM)研究了施加恒定外电场时,AFM针尖与云母表面间的摩擦力变化情况.结果表明,对样品基底施加一定偏压后,由于针尖与云母表面间的静电作用增强,使得针尖与样品间的总相互作用势增加,从而导致针尖与云母间的摩擦力比未施加偏压时大,且摩擦力大小随电压升高而增大.尤其是施加负偏压时,摩擦力增加更为显著,且大于正偏压时的摩擦力.     

功能性羊毛纤维的制备

以钛酸四丁酯为前驱体,在水热环境中直接将纳米二氧化钛负载到羊毛纤维表面,使用扫描和透射电镜、红外光谱、热重和漫反射光谱测试技术对羊毛纤维改性前后表面形貌、结构、热学和光学性能进行了表征,并测定羊毛纤维拉伸、表面摩擦和自清洁性能.研究结果表明,钛酸四丁酯合成的锐钛矿型纳米二氧化钛颗粒平均粒径约5nm,通过化学键接枝在羊毛纤维表面.较未处理羊毛纤维,改性后的羊毛纤维热学性能变化不明显,吸收紫外线能力有所增强,断裂伸长率有所增加,摩擦因数增大而摩擦效应减小,具有光催化自清洁性能.     

碳纳米管操纵中的微观摩擦问题

为了充分掌握纳米操纵中的微观摩擦规律,消除微观摩擦对纳米操纵的不利影响,该文利用原子力显微镜(AFM)的超微探针作为操纵工具,对具有优异力学和电学特性的碳纳米管在不同的表面状况下进行了剪切和操纵。实验中发现,当基底的表面成分和表面形貌不同的时候,操纵过程中的微观摩擦力会有明显的变化。从与光刻技术相结合的操纵实验中可以看出,光刻后残留的光刻胶会大大增加碳纳米管与基底间的微观摩擦力,并加剧操纵工具——AFM针尖的污染与磨损。     

汽缸套-活塞环磨合过程摩擦力矩分形行为研究

针对缸套-活塞环磨合过程摩擦力矩的变化特点,提出一种用分形维数描述摩擦力矩信号复杂性的新方法.从工程应用角度介绍了摩擦力矩信号盒维数的计算方法,通过试验研究了缸套-活塞环磨合过程中摩擦力矩信号盒维数的变化规律.结果表明随磨合磨损的增加,摩擦力矩信号盒维数呈上升趋势,且在不同的润滑方式下,摩擦力矩信号盒维数上升趋势不同,运用摩擦力矩信号盒维数可有效地评价磨合过程.     

钛合金表面稀土改性双层羧基化石墨烯复合薄膜的摩擦磨损性能

利用自组装成膜技术在钛合金基片表面制备了稀土改性双层羧基化石墨烯复合薄膜,采用接触角测量仪测量薄膜表面的接触角,采用扫描电子显微镜观察薄膜表面的微观形貌,并利用UMT-2MT型摩擦磨损试验机及原子力显微镜研究薄膜的宏观及微观摩擦磨损性能.结果表明:所制备的稀土离子改性双层羧基化石墨烯复合薄膜具有优异的摩擦磨损性能;相比于单层薄膜,稀土改性双层羧基化石墨烯复合薄膜具有更低的摩擦系数和微观摩擦力,表现出更优异的宏观及微观摩擦磨损性能.     

一种有机硅烷/稀土复合薄膜制备及纳米摩擦学性能

采用分子自组装技术在单晶硅基底上制备了有机硅烷/稀土（APTES/RE）复合薄膜.利用椭圆偏振仪、接触角测量仪及X射线光电子能谱(XPS)仪分析表征了薄膜的结构,并采用原子力显微镜（AFM）研究了硅基片和复合薄膜的纳米摩擦学性能.结果表明：随着探针的滑动速度和载荷的增加,针尖与样品间摩擦力增加;硅基片和复合薄膜表面的黏附力和摩擦力随着相对湿度的升高而增大;APTES/RE复合薄膜具有较低的摩擦系数及黏附力和显著的抗黏着及减摩效果,显示出其在微机构表面润滑中良好的应用前景.     

软磁盘、硬盘的表面形貌和微摩擦特性

利用原子力／摩擦力显微镜,对市售的５种软磁盘及一种硬盘的表面形貌、１～１００ｎＮ载荷下的微摩擦性能及表面粘着性能进行了研究。结果表明：软磁盘主要由块状的磁粉颗粒组成;硬磁盘由环状磁道组成。硬盘的微摩擦力、表面粘着力、摩擦因子大于同样条件下的软磁盘,１２９ｍｍ（５．２５英）软磁盘的微摩擦力、表面粘着力、摩擦因子大于同一品牌的８６ｍｍ（３．５英）的软磁盘;探针与磁记录介质在大于２０ｎＮ载荷下的接触为塑性接触。     

原子力显微镜形貌像成像质量的研究

基于针尖和样品之问的各种相互作用力，原子力显微镜可用于样品表面形貌、摩擦力等各种物理特性的研究。仪器参数的设定和干扰的排除是提高样品表面形貌像成像质量的关键。通过实验发现由原子力显微镜扫描得到的材料表面形貌像中常出现拖曳、条纹，影响了形貌像的成像质量。针对特定工艺条件下的纳米电子功能薄膜样品，着重研究了振幅参数（Amplitude reference）、积分增益（Integral gain）、比例增益（Proportiong ain）、衰减增益（Attenuation gain）和速度增益（Speed gain）对形貌像成像质量的影响。根据这些规律找出消除或减轻样品表面形貌像中出现拖曳、条纹的方法。     

APTES湿法修饰对绢云母粉末粗糙表面张力的影响

对绢云母(Sericite)粉末进行硅烷偶联剂湿法处理,采用Washburn 法测量了经不同浓度的硅烷偶联剂修饰后的绢云母粉末的表面张力.修饰后的绢云母粉末的表面张力具有周期性的变化,且波峰与波谷随着3-氨基丙基三乙氧基硅烷(APTES)用量的增加而增大.利用比表面仪(BET)和激光粒度仪,获得绢云母粉末表面的粗糙度为17.5,且根据Wenzel 和 Cassie复合方程,获得液体与粗糙表面接触的投影面积分数f2为0.103,在绢云母粉末表面的单分子层APTES密度为1.82×1018 个/m2.     

Pd-ZSM-5复合膜的制备及其氢气分离性能

为了能够在大孔氧化铝载体表面得到透氢性能良好的钯膜,利用二次生长法在多孔Al₂O₃载体上生长出一层连续完整的ZSM-5沸石分子筛修饰层,通过化学镀过程在ZSM-5沸石分子筛修饰的载体上沉积一层钯膜,从而得到Pd-ZSM-5复合膜。利用扫描电子显微镜(SEM)对载体、ZSM-5沸石分子筛修饰后的载体和Pd-ZSM-5复合膜的形貌进行详细分析,并通过X线能量色散光谱(EDX)对Pd-ZSM-5复合膜的表面和截面元素分布进行了研究。而且,为了确定该Pd-ZSM-5复合膜的H₂渗透性能,在623～773 K范围内,研究了操作温度、操作时间和测试压力对Pd-ZSM-5复合膜透氢性能的影响。研究结果表明,ZSM-5沸石分子筛修饰层能够有效改进载体的表面粗糙度和降低其表面孔径,有助于Pd膜的沉积。所制备的Pd-ZSM-5复合膜表面完整、致密,Pd膜层厚度约为5μm, ZSM-5沸石修饰层厚度约为3μm。当操作温度为773 K、渗透压力为0.1 MPa时,Pd-ZSM-5复合膜的H₂渗透通量和H₂     

The experimental rules of mica as a reference sample of AFM/FFM measurement

For the friction measurements with AFM/FFM, usually the relative values of friction signal can be obtained. In order to compare the micro-tribological properties of different samples, mica is often used as an reference sample for friction measurement. However, due to the friction force of new cleaved mica surface is unstable, it is urged to systematically investigate the tribological properties of mica to design the experimental rules of the reference sample mica for friction measurements. Experimental results show that the friction of mica varies with the cleaving time, humidity and surface state of tip. The friction measured with different tips on mica varies in the range of ± 15%. For a new tip, the friction increases with the tip’s wear and then becomes stable. For new cleaved mica, the friction increases within the first two hours and then keeps unchanged. The friction of mica also decreases with the relative humidity because of its hydrophilicity.     

磁控溅射GeSbTe相变薄膜黏附与摩擦特性

室温下通过调整磁控溅射时间制备了不同厚度的GeSbTe薄膜.利用原子力显微镜和台阶仪观察薄膜的表面形貌,测量薄膜厚度,并借助TriboIndenter纳米力学测试系统,分析探讨了薄膜的黏附和摩擦特性.研究结果表明:随着溅射时间的增加,薄膜表面粗糙度减小,厚度增加,同时表面质量提高;探针直径、相对湿度、薄膜表面质量以及探针载荷等因素对薄膜的黏附和摩擦特性均有重要影响;在满足存储要求的前提下,通过减小探针直径、降低相对湿度能够有效降低黏附力和摩擦力;而提高薄膜表面质量,为探针施加合适的载荷,有助于改善探针与薄膜表面之间的摩擦特性.     

Determination of hydration film thickness using atomic force microscopy

Surface forces between particles control phenomenasuch as dispersion, agglomeration, coatings, adhesion,wetting, friction, and polishing, which play a crucial rolein materials processing. The importance of surface forcesis more appreciated especially in colloidal processing,while materials in a colloidal state are frequently preferredin industrial processing operations (e.g., printing inks,toners, paints, skin creams, blood substitutes, gels used asdrug-delivery systems, etc.) because their lar…     

Friction behavior of coupling motion for natural articular cartilage by reciprocating rotation

Based on the irregular surface of natural cartilage configurations, the tribological characteristics of coupling motion between natural cartilage pairs were investigated by the variation of rotated offset and velocity. Contact displacement, contact load, friction force and coefficient of friction from natural cartilage pairs were measured by a UMT-2 testing machine. In order to obtain the steady part and wavy part, the contact load and contact displacement were decompounded by the five-point sliding average method. These results showed that the contact load was composed of steady load and wavy load. And the contact displacement was composed of cartilage deformation and surface outline. The steady load was similar to exterior load while natural cartilage deformation increased nonlinearly with the sliding time. Wavy load had the correlative coefficient 0.235 with surface outline due to the irregular surface of friction configurations. The coefficient of friction from cartilage friction configurations was less influenced by smaller magnitude in rotated parameters. A few strange summits were obtained in the area of coefficient of friction, and significantly related with local minimal values corresponding to the contact loads. The rotated offsets had clear impact on contact load and a slight impact on contact displacement. Larger offset produced higher wavy magnitude of the contact load. The rotated velocities played an evident role in cartilage deformation, but had a less influence on contact load. Lower velocity brought larger cartilage deformation. Contributed equally to this work Supported by the National Natural Science Foundation of China (Grant No. 50535050)     

Dynamic evolution of adhesion force between protein films studied by atomic force microscope

The approaching of two hydrophobic surfaces in water will lead to the combination of air bubbles adsorbed on the surfaces, thus additional long-range attraction is induced due to the bridging capillary force. Theoretical analysis shows that the process is a first-order phase transition, while no direct experiment supports the predication. The interaction between protein modified tip of atomic force microscope and protein film on mica was studied. The results demonstrate that the adhesion force between them increases to a stable value during the calibration process and the evolution clearly indicates the character of first-order transition.     

铝金属薄膜上制备OTS自组装分子膜的摩擦学特性

为研究铝金属薄膜上三氯十八硅烷(OTS)自组装分子膜的摩擦学特性,采用自组装的方法在铝金属薄膜上制备OTS自组装分子膜,分析了纳米尺度和毫牛尺度下载荷、滑动速度以及紫外照射对薄膜摩擦学特性的影响.结果表明:制备的OTS自组装分子膜具有疏水特性和良好的润滑性能.紫外照射5 min后,自组装分子膜摩擦力降低;紫外照射15 min时,自组装分子膜的网状结构受到破坏,减弱了润滑效果.在纳米尺度和毫牛尺度下,摩擦力随载荷和滑动速度的增大而增大;铝金属薄膜摩擦系数降低时,自组装分子膜磨损显著降低,摩擦副的耐久性略有提高.     

Effect of humidity on the surface adhesion force of inorganic crystals by the force spectrum method

Effect of relative humidity on the surface adhesion force of several inorganic crystals of mica, CaF₂ and KCl was studied by atomic force microscopy (AFM). The results showed that the magnitude of surface adhesion force is mainly dependent on the surface free energy of the adsorbed liquid film, but almost independent of the thickness of the film. Furthermore, the deliquescence on the crystal surface was investigated, which demonstrated the capability of the force spectrum method to monitor changes in ionic concentrations of adsorbed liquid film in real-time.     

导电原子力显微镜在介质薄膜电流图像检测中产生的假像

对导电原子力显微镜在介质层电流图像检测中存在的假像进行了研究。发现这种假像归因于导电探针针尖较大的直径,其大小与被检测样品表面的缺陷点、漏洞、沟穴大小相关。研究表明,为提高图像分辨率,避免检测过程中存在的假像,需要使用具有纳米直径针尖的超尖导电探针。     

仿生凹坑与纳米碳化硅/镍基复合镀层耦合表面的磨损性能

为了探讨凹坑形态与纳米碳化硅/镍基复合镀层耦合表面的磨损性能,采用激光技术和电沉积技术制备了由凹坑形态和纳米碳化硅/镍基复合镀层构成的仿生耦合表面,并进行了摩擦和磨损试验。结果表明,仿生耦合表面的磨损性能高于单纯复合镀层的磨损性能;随着磨损载荷的增加和磨损时间的延长,试样表面磨损机制由以塑性磨损为主逐渐转变成以粘着磨损、磨粒磨损为主的磨损机制。     

基于原子力显微镜的纳米尺度摩擦力的速度依赖关系

以硅为探针、带有自然氧化物的硅(100)晶面为基底样品,利用原子力显微镜研究了探针扫描速度对于单个微凸体系统中摩擦力的影响.首先,利用热噪声标定法测量出硅悬臂梁的法向弹簧常数和法向灵敏度;然后,利用改进的楔形校准法,通过扫描三角光栅得出侧向灵敏度;最后,测量出扫描区域为15μm×15μm、正压力为-5～10 nN、扫描速度为2.5～1 000μm/s下的摩擦力.实验结果表明,不同速度下摩擦力随正压力的增加呈近似线性增加,服从经典库仑定律.当扫描速度小于40μm/s时,速度增加所导致的摩擦力的增加不明显;当扫描速度大于40μm/s时,速度增加则引起摩擦力急剧增加.该结果与热激发的Tomlinson模型的计算结果吻合.