The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method （FEM） aimed to reveal the effect of punch size on the indentation behavior of the film/substr...The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method （FEM） aimed to reveal the effect of punch size on the indentation behavior of the film/substrate system. Based on the FEM results analysis, two methods was proposed to separate film＇s reduced Young＇s modulus from a film/substrate system. The first method was based on a new weight function that quantifies film＇s and substrate＇s contributions to the overall mechanical properties of the film/substrate system in the flat cylindrical indentation test. The second method, a numerical approach, including fitting and extrapolation procedures was put forward. Both of the results from the two methods showed a reasonable agreement with the one input FE model. At last, the effect of maximum indentation depth and the surface micro-roughness of the thin film on the reduced Young＇s modulus of the film/substrate system were discussed. The methods proposed in the present study provide some new conceptions on evaluating other properties of thin films, e.g. creep, for which a flat-ended punch is also employed.展开更多
The experimental results indicate that the Ni-ZrO2 composites synthesized with urn-sized Ni powder and nm-sized ZrO2 powder possess submicron structure. Based on the fractal theory, the relationship between the electr...The experimental results indicate that the Ni-ZrO2 composites synthesized with urn-sized Ni powder and nm-sized ZrO2 powder possess submicron structure. Based on the fractal theory, the relationship between the electric and thermal conductance and the chemical composition of the composites has been studied. The results show that with the increase of the nickel content, the electric and thermal conductance of the composites varies. It is proposed that in the submicron structured composites, electrons and phonons have different transport mechanisms. The electric transport in the submicron-structured composites can be attributed to the medium punch-through effect and quantum tunnel punch-through effect of electrons and the low thermal conductance is due to the phonic scattering by the submicron-sized pores, grains and grain boundaries. The reason can also be used to explain why the thermal percolation threshold value lags behind the electric percolation value. The phenomenon has been observed.展开更多
基金supports from National Natural Science Foundation of China (Nos.50775183 and 50805118)Research Fund for Doctoral Programof higher Education (N6CJ0001)National High Technical Research and Development Programme of China (No.2009AA04Z418)
文摘The flat cylindrical indentation tests with different sizes of punch radius were investigated using finite element method （FEM） aimed to reveal the effect of punch size on the indentation behavior of the film/substrate system. Based on the FEM results analysis, two methods was proposed to separate film＇s reduced Young＇s modulus from a film/substrate system. The first method was based on a new weight function that quantifies film＇s and substrate＇s contributions to the overall mechanical properties of the film/substrate system in the flat cylindrical indentation test. The second method, a numerical approach, including fitting and extrapolation procedures was put forward. Both of the results from the two methods showed a reasonable agreement with the one input FE model. At last, the effect of maximum indentation depth and the surface micro-roughness of the thin film on the reduced Young＇s modulus of the film/substrate system were discussed. The methods proposed in the present study provide some new conceptions on evaluating other properties of thin films, e.g. creep, for which a flat-ended punch is also employed.
基金the State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China
文摘The experimental results indicate that the Ni-ZrO2 composites synthesized with urn-sized Ni powder and nm-sized ZrO2 powder possess submicron structure. Based on the fractal theory, the relationship between the electric and thermal conductance and the chemical composition of the composites has been studied. The results show that with the increase of the nickel content, the electric and thermal conductance of the composites varies. It is proposed that in the submicron structured composites, electrons and phonons have different transport mechanisms. The electric transport in the submicron-structured composites can be attributed to the medium punch-through effect and quantum tunnel punch-through effect of electrons and the low thermal conductance is due to the phonic scattering by the submicron-sized pores, grains and grain boundaries. The reason can also be used to explain why the thermal percolation threshold value lags behind the electric percolation value. The phenomenon has been observed.
