Papers by Keyword: Nanometer-Scale

Abstract: Scanning electron microscope (SEM) observation showed that femur bone is a kind of bioceramic composite consisting of hydroxyapatite layers and protein matters. The hydroxyapatite layers are further composed of hydroxyapatite fiber sheets. The observation also showed that the hydroxyapatite fiber sheets possess very thin fiber shape. The thickness of the hydroxyapatite fiber sheets is within nanometer scale. The mechanism of the high fracture strength of the bone was investigated based on the microstructural characteristics of the hydroxyapatite fiber sheets and the theory of fracture mechanics. The result reveals that the thin fiber shape of the hydroxyapatite fiber sheets endows the bone with high fracture strength.

Abstract: Nanocrystalline zeolite β was synthesized by hydrothermal treatment, and the effect of aluminium source, SiO2/Al2O3 ratio, sodion, crystallization temperature etc. on particle size and morphology was studied. Under the optimum condition, zeolite β with the particle size about 100nm was successfully synthesized. The samples were characterized by XRD and TEM techniques, and the key factors influencing the particle size and morphology were revealed.

Abstract: A method of straightness error compensation is presented, which is used in ultra-precision machining with nano-scale accuracy for a large mandrel manufacture. A set of measurement system in situ is developed, in which an ultra-smooth glass-ceramic flatness gauge and a non-contact micro displacement sensor with nano-scale resolution were used as a reference and sensor to get the straightness error of machine tool movement. The real straightness error can be obtained after subtracting the surface profile of the gauge from the original straightness error curve. Based on the real straightness error data, a new NC program was made for compensating the error from the axis movement of machine tool. As a result, after straightness error compensation, the straightness errors of two axes of ultra-precision machine tool are 68nm/400mm and 54nm/300mm respectively.

Abstract: Fatigue tests of nanometer-thick Cu films as deposited and annealed in vacuum were conducted under constant load ranges at room temperature. Fatigue strengths of the Cu films, which is defined as the critical load range being able to cause crack initiation within 106 cycles, are determined. The experimental results show that fatigue strength increases with decreasing film thickness. Fatigue cracking behaviors were characterized by electron microscope. It is also found that fatigue cracking resistance is dependent on film thickness and increases with decreasing film thickness. Size effects on fatigue properties of the nanometer-thick Cu films are discussed.

Abstract: Direct Wafer Bonding has been widely developed and is very attractive for a lot of applications. Using original techniques based on direct bonding enable to carry out specific engineered substrates. Various illustrations are given among which twisted Si-Si bonded substrates, where buried dislocation networks play a key role in the subsequent elaboration of nanostructures.

Abstract: To realize ultrahigh density recording in high precision using polycarbonate as a recording media, the nanometer-scale mechanical processing properties of polycarbonate and fluorocarbon plasma-treated polycarbonate were investigated using atomic force microscopy (AFM). The surface free energy of the polycarbonate specimen can be reduced by fluorocarbon plasma-treatment, resulting in processing force being reduced. Thus, nanometer-scale precise processing of polycarbonate can be realized. Lines and spaces with intervals minimized to 60 nm were performed on the fluorocarbon plasma-treated polycarbonate. Viscoelastic properties of the fluorinated polycarbonate were evaluated using AFM in force modulation mode. Fluorocarbon plasma treatment can reduce friction force of a polycarbonate sample and improve its wear resistance. Therefore, the friction durability corresponding to the reliability of data reproduction was markedly improved.