【作者】 张晓峰；

【导师】 张平余； 杜祖亮；

【作者基本信息】 河南大学 ， 凝聚态物理， 2007， 硕士

【摘要】 LB膜作为超薄润滑膜有望解决磁记录、MEMS/NEMS等高新技术中运动部件的摩擦磨损问题。LB膜作为薄膜润滑成功应用于工程实际的两个关键难点是设法提高其负荷承载能力、热稳定性和提高膜基结合强度。而自组装技术不受基底材料和形状的影响,适合于大面积组装,是一种简单制备纳米润滑薄膜的有效方法。本论文主要涉及到以下两方面的工作:一、结合LB技术制备ZrO₂润滑薄膜的研究结合LB技术在单晶硅表面制备了致密的ZrO₂薄膜,AFM测试表明所制备的ZrO₂薄膜表面形貌与层数呈现明显的对应关系。LB膜层数为7时,薄膜由粒径大约为30纳米的致密颗粒组成,没有明显的裂纹存在,表面致密均匀,形貌均一。在LB膜层数为1时,所得ZrO₂薄膜表面由稀疏颗粒组成;而当层数达到50时,相应的ZrO₂薄膜表面凸凹不平,呈现明显的多层堆叠。XPS测试表明:薄膜表面除了少量的硫酸锆盐外,主要成分为ZrO₂。摩擦磨损实验表明:利用该方法制备的ZrO₂薄膜适于在低载荷,低滑动速度下作为减摩抗磨保护涂层。在润滑初始阶段,磨损机理为轻微擦伤,而较长磨损时间后,磨痕表面呈现较严重的塑性变形,表现为擦伤和剥落的特征。二、结合LB和自组装技术制备La2O3润滑薄膜的摩擦学研究我们分别结合LB和自组装技术在羟基化的Si表面成功制备了氧化镧薄膜。我们对两种样品分别进行了AFM表征。可以看出,结合LB技术制备的氧化镧薄膜的表面形貌与所提取LB膜的层数呈现一定的对应关系。随着所提拉花生酸镧LB膜层数的增加,薄膜表面颗粒密度逐渐增大。而结合自组装技术制备的氧化镧薄膜的表面形貌均匀,薄膜表面由致密均匀小颗粒组成,但伴有少量团簇颗粒存在。XPS元素分析表明:两种薄膜均由La₂O₃构成。摩擦磨损试验结果表明,利用这两种方法制备的薄膜均表现出优异的减摩耐磨性能,具有低的摩擦系数和长的耐磨寿命。并结合磨痕的SEM图像探讨了两种薄膜的摩擦润滑机理。我们对这两种薄膜分别进行了归属,认为结合LB技术制备的薄膜表现为脆性薄膜的摩擦磨损特征,粘结点的破坏主要是剥落,损伤深度较浅,磨损机理为轻微擦伤;而结合自组装技术制备的薄膜表现为塑性薄膜的摩擦磨损特征,粘着结点的破坏以塑性流动为主,破坏深度较大。更多还原

【Abstract】 As an ultrathin lubrication films, LB films are helpful to solve the friction and abrasion of running components of high technologies such as magnetic record, MEMS/NEMS. Two key difficulties which LB films are applied to engineering are the following: one is to enhance the ability of load-carrying or thermal stability; the other is to improve the cohesion strength between film and substrate.Moreover, self-assembly technique is uninfluenced by substrate materials and shapes, fit for assembly in large scale and is a simple and effective method to prepare nanolubricant thin films.The thesis mainly includes two parts:Part One: Preparation and tribological behaviors of ZrO2 thin films combined with Langmuir-Blodgett technique Zirconium oxide thin films on Si (111) substrate with controllable thickness in nanometer scale were prepared by annealing LB films of zirconium salt of arachidate at 500℃for 30 minutes. The microstructure, morphology and wear mechanisms of the film were analyzed based on atomic force microscopic, X-ray photoelectron spectrometric, and scanning electron microscopic observations of the original and worn surfaces of the films. As shown in the topography image, ZrO2 thin film is composed of compact particles whose diameters range from 20nm to 30 nm, and has no obvious cracks. XPS survey spectra of ZrO2 thin film demonstrates that the silicon substrate is covered by ZrO2 completely with little noncrystalline Zr(SO4)2. After sliding 500 cycles under a low load of 0.5N the worn ZrO2 thin film showed a slick surface and shallow and narrow furrows due to mild scratching without cracks and peels corresponding with its lower friction coefficient and longer antiwear life. After sliding 3,000 cycles discontinuous plastic deformation and grits occur attributed to shearing strength, and these debris in wear tracks accelerated wear and obvious furrows formed. With the increasing of sliding cycles, the worn surface is characterized by severe plastic deformation, scuffing and spalling.Part Two: Tribological properties of La2O3 thin films prepared by Langmuir-Blodgett and self-assembly techniqueLa2O3 thin film deposited on Si <111> was successfully prepared by LB and self-assembly technique, respectively. As shown in the topography image, La2O3 thin film by LB technique is composed of nanoparticles whose diameters range from 100nm to 120 nm, and the density of the particals increases with the deposited layers of LB films of lanthanum salt of arachidate. However, the self-assembly thin film is covered by compact and uniform particles with few clusters. From XPS analysis we can conclude both of the films are composed of La2O3. La2O3 thin film by LB technique showed a tribological behavior of brittle thin films, invalidation of the film was characterized by spalling, abrasive dust sloughing and shallow damage depth. And heat treatment in preparation reduced adhesion effects, and the lubricant film also confined damage depth, leading to improved anti-stiction capability. However, the self-assembly film has a strong anti-stiction capability due to its low shear strength, and obvious shear deformation can be observed. Meanwhile, fresh film formed after abrasion leading to polished surface and then weak plowing effects, corresponding to its quite low friction coefficient. So the self-assembly film was acknowledged as a plastic film, invalidation of the film was characterized by plastic deformation, with higher damage depth and larger abrasive dusts.更多还原