Zhen Jiang Hu

Fabrication of microstructures on the surface of a micro/hollow target ball by AFM

An AFM-based mechanical scratching technique is employed to fabricate microstructures with a depth of several nanometers on the surface of a micro (the diameter is 0.1–0.5 mm) thin wall and a hollow (the thickness of the wall is 0.8–1.2 µm) glass target ball. Based on analysis of the materials removal mechanism on the hollow target ball surface by an AFM diamond tip, effects of the normal load, fixed conditions on the machining process are studied. Using the AFM-based nanomachining system which is integrated with a high-precision stage, triangular and circular microstructures are fabricated on the target ball surface. Moreover, square taper holes are fabricated by this technique which solves the problems of fabrication of micro inflation holes in inertial confinement fusion (ICF) experiments. It indicates that the AFM-based mechanical machining approach has potential applications in the fields of machining a curved surface and real three-dimensional microstructures.

Depth Control Method of AFM-Based Nanomachining with Diamond Tip in Deflection Mode

The equations correlated the normal load and the tip penetration depth were derived through the theoretical analysis of the penetration process of the diamond tip. Verified by experiments, the equations can reflect the penetration process of the scratching machining system and provide theoretical basis for the optimization of depth control algorithm. The control of scratching depth realized in AFM deflection mode can effectively restrain the system drift during scratching process.

Effect of Sample Materials on the AFM Tip-Based Dynamic Ploughing Process

To study the effect of different sample materials on the nano dynamic ploughing process in the AFM tapping mode, the spring-oscillator model is employed to simulate the vibrating AFM tip to deform the sample surface. On the surface of different samples with the Young’s modulus of 0.2 GPa, 80 GPa and 180 Gpa, the interaction between the tip and the sample is simulated with different driven amplitudes, spring constants, tip radius and original tip-sample distances. These effects are studied. Results show that the sample with a smaller Young’s modulus is suitable for being used as the sample machined by the dynamic ploughing technique. When the Young’s modulus is greater than 80 GPa, the machine depth is so small that the machining process can not be controlled as we required.

In Situ Nanoscale Deformation Studies on Micro Copper Wires Using Atomic Force Microscopy

As the dimensions of parts become smaller, understanding the mechanical properties of these small components was becoming more important. Till present day, the methods and technology used to investigate the deformation behavior in nanoscale were still lacking. In this paper, the specimens were single crystal copper wires with diameter in 50 microns. Atomic force microscope integrated with an in- situ tensile system were used to determine the mechanical behavior of copper wires and observe the surface topography deformation in nanoscale simultaneously. The results were as follows: the modulus of elasticity, tensile strength and failure strain of the sample were 167Gpa, 0.564GPa and 0.011, respectively. By using AFM, the separation process between the copper wire and impurities on it, such as oxide film, was observed. The nanoscale deformation process of the copper wire was also obtained.

Optical and mechanical properties of nanocrystalline silicon dioxide films prepared by medium frequency magnetron sputtering

Nanocrystalline silicon dioxide (SiO2) films were prepared on aluminium substrates using medium frequency magnetron sputtering. The surface morphology of SiO2 film on aluminium substrate was observed using atomic force microscopy. The nanohardness and the elastic modulus of the SiO2 film-aluminium system were measured by a nanoindentation technique. Moreover, optical propertie of SiO2 film-aluminium system was investigated. It was found that the composition of silicon dioxide films varies from nearly pure Si, SiO to SiO2, controlled by O2 flow rate. The reflection index of nanocrystalline SiO2 film-aluminium system is accord with the mixture rule. All SiO2 films are transparent and the transmittance increases with increasing O2 concentration.

Penetrating Process Analysis of AFM Diamond Tip

A mechanical micro-scratching system based on Atomic Force Microscope (AFM) and three-dimensional high precision stage was built up. In the machining process with diamond tip, the process of depth controlling was determined by the relation between the loading movement of the stage and the tip penetration depth. By theoretical analysis of loading process with diamond tip, a mathematical model correlated loading movement and the penetration depth was founded, and the loading efficiency formula of elastic tip was also acquired. Verified by experiments, such equations reflected the indenting process of the system and provided theoretical basis on optimizing the penetration depth control arithmetic.Copyright

Three-Dimensional Micromachining Based on AFM

With the development of science and technology, Atomic Force Microscope is widely applied to the field of machining process in nanometer scale. Due to the limitation of the inventive purpose of AFM, only height mode and deflection mode can be applied in AFM-tip micromachining. It can’t control the machining depth during the micromachining process at present. In this paper, a new micromachining system is set up, which composed of a high precision three-dimensional stage, an AFM, a diamond probe and a special control device. By utilizing variation parameters PID algorithm and controlling the machining depth directly, the micromachining system can resolve the problem mentioned above.