Papers by Author: Han Huang

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Authors: Han Huang
Abstract: This paper summarised our recent results on the development of grinding technologies for the fabrication of aspheric components at micro/meso scales made of cemented tungsten carbide. Based on these results, a grinding protocol was proposed for the fabrication of aspheric moulds. The protocol includes the understanding of deformation and removal mechanisms of hard and brittle materials involved in grinding, the preparation of grinding wheels, the compensation of profiling errors and the optimisation of the grinding process.
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Authors: Cheng Wei Kang, Bing Jun Hao, Han Huang
Abstract: This study aimed to investigate the effect of grinding conditions, including depth of cut and grinding direction, on the material removal and surface finish of multilayered thin film structures. It was found that the increase in depth of cut improved the material removal rate, but worsened the ground surface finish. The grinding perpendicular to the thin films caused less damage and produced better surface than that parallel to the films. The characteristics of wheel wear were also studied. Grit pull-out and micro-fracture should be attributed to the wheel wear.
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Authors: Cheng Wei Kang, Han Huang
Abstract: Tungsten based products are extensively used in engineering practices. However, there exist some controversies in deformation behaviour between polycrystalline tungsten and its bulk counterpart. In this work, elastic modulus, hardness and removal characteristics of polycrystalline tungsten (poly-W) were investigated by use of nanoindentation and nanoscratch. Atomic Force microscopy (AFM) and Scanning Electron Microscopy (SEM) were employed to characterize the surfaces prior to and after indenting/scratching. The elastic modulus and hardness of the poly-W obtained were 323.6 and 7.1 GPa, respectively. Elastic recovery was barely observed in poly-W after indenting and scratching, indicating that the material was dominantly deformed in plastic regime. The plastic deformation of the poly-W was found to be somehow different from the bulk W, but similar to that of single crystal W nanowhiskers. In multi-scratch test, the pitch distance and scratching speed demonstrated to affect the roughness of the scratched surfaces.
706
Authors: Chih Ling Lin, Han Huang, Bronwen W. Cribb, Anthony Russell
Abstract: Human bone fracture associated with osteoporosis was hypothesized to be related to the alteration of mechanical properties in bones. In this work, cortical and trabecular bones from human femoral heads were studied. Bone samples of eight female and four male patients, with ages varying from 37 to 93 years, were collected from total hip replacement surgery. Reduced modulus (Er) and hardness (H) of osteons, interstitial lamellae and trabeculae were characterized by nanoindentation. The results showed both the reduced modulus and hardness of the interstitial lamellae were significant higher than those of osteons and trabeculae. Though there was no significant difference in microstructures in the Group A (age < 60 years) and B (age > 60 years), the Group B bones demonstrated to be stiffer.
957
Authors: Han Huang, Rudy Irwan, Tsunemoto Kuriyagawa
Abstract: Nanoindentation was used to study the deformation and removal mechanisms of cemented tungsten carbide. It was found that the microstructure of the material has significant influences on its mechanical properties, which determines the critical conditions for damage-free nanogrinding. The results also indicated that when material removal events occur at nanometric scale, such influences should be taken into account for gaining the full potential of nanogrinding.
385
Authors: Ming Yuan Lu, Hong Tao Xie, Han Huang
Abstract: This review summarized the research works on the characterisation of interfacial adhesion in thin film/substrate bilayer structure by use of indentation testing. It focused on the delamination mechanics between a thin film and a substrate induced by indentation and the quantitative characterisation of interfacial strength in such bilayer systems. Three major techniques were introduced, namely conventional indentation, cross-sectional indentation and acoustic emission assisted indentation. A number of theoretical models and finite element simulation studies were discussed, in association with the experimental investigations. Key words: Thin film, bilayer, delamination, adhesion, indentation, acoustic emission
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Authors: Zhi Gang Dong, Han Huang, Ren Ke Kang
Abstract: Nanoindentation tests with the aid of acoustic emission monitoring were performed on single crystal MgO (001) plane to investigate the deformation of MgO under high indentation pressures. The results indicated that the deformation of MgO under nanoindentation with a sharp indenter could be classified into three stages: elastic deformation, elastoplastic deformation, and fragmentation. The elastic energy release and fracture occurred could be identified using acoustic emission signals.
404
Authors: Cheng Wei Kang, Han Huang
Abstract: The deformation and removal mechanism of a multilayered thin film structure involved in nanoscratching and diamond lapping processes were investigated. The results obtained from the two processes were compared, in terms of deformation characteristics and surface finish. It was found that both nanoscratching and lapping demonstrated similar characteristics. This work provides insight into the deformation and removal of a thin film multilayered structure under mechanical loading, and thus the outcome is of value for developing the efficient machining process for such structures.
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Authors: Han Huang
Abstract: The machining of thin film multilayered solar panels is facing a great challenge in industry due to the low machining efficiency, and a timely solution is needed if this approach is to progress further. The successful employment of a new machining technology for the solar panels requires comprehensive understanding of the deformation and removal mechanisms of nanoscale multilayered materials, which has never been previously achieved. This paper reviewed the understanding of mechanics of nanoscale multilayer structures, and reported the recent progress on the development of abrasive machining technologies forthin film multilayered structures.
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Authors: Y.Q. Wu, Han Huang, Jin Zou
Abstract: In this work, deformation of monocrystalline silicon (Si) under nanoscratching was investigated using transmission electron microscopy (TEM). The results indicated that no fracture occurred during nanoscratching with loads ranging from 1 to 6 mN. The damaged regions induced by nanoscratching included an amorphous Si region and a damaged crystalline Si region. Detailed TEM analyses revealed that at the lowest load of 1 mN no dislocation was observed in the damaged crystalline region, and only stacking faults were observed at the boundary between the damaged crystalline Si and amorphous Si. Dislocations started to nucleate along (111) planes and penetrated into the bulk Si when the normal load was increased to 2 mN and above. Defects perpendicular to the scratched surface were initiated when the load was greater than 4 mN. The density of dislocations also increased rapidly with the increase of the applied load.
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