基于通用力场(Universal Force Field,UFF)方法对二氧化锆纳米管进行结构优化,并计算得到了Zr-O键等效梁单元力学性质。通过等效梁单元模拟Zr-O键,质量单元模拟Zr原子和O原子,建立Zr NTs分子结构有限元模型。研究了手性、直径和长度对...基于通用力场(Universal Force Field,UFF)方法对二氧化锆纳米管进行结构优化,并计算得到了Zr-O键等效梁单元力学性质。通过等效梁单元模拟Zr-O键,质量单元模拟Zr原子和O原子,建立Zr NTs分子结构有限元模型。研究了手性、直径和长度对一端固定和两端固定结构固有频率的影响。结果表明:手性几乎不影响Zr NTs的固有频率;随着直径的增大,两端固定结构固有频率先增大后减小,一端固定结构固有频率增大;随着长度的增大,固有频率减小,二氧化锆纳米管在长径比小于3时,固有频率随长度的增加而急剧减小,长径比大于3时,固有频率的减小幅度随长度的增加明显降低。展开更多
Prestressed SUS316 fibers/ZrO2 composite was fabricated using tape casting. Causes of cracks were analyzed by classical thermo-elastic theory and finite element method in preparation process. An optimization design wa...Prestressed SUS316 fibers/ZrO2 composite was fabricated using tape casting. Causes of cracks were analyzed by classical thermo-elastic theory and finite element method in preparation process. An optimization design was carried out on SUS316 fibers’ arrangement modes by reducing residual thermal stress. Interface topography and element distribution of composite were observed, and bending strengths were tested. Results show that cracks are generated along the direction vertical to SUS316 fibers by axial thermal stress due to different thermal expansion coefficients between SUS316 fibers and zirconia, and the average cracking space is 2 mm. No macroscopic defect is found in composite with SUS316 fibers of sine distribution, and it has better interfacial binding force since interdiffusion between SUS316 and zirconia. Bending strengths of composite with 0°/0°lamination are anisotropic and that are 385.74 MPa and 500.7 MPa respectively, but that with 0°/90°lamination is isotropic and it is 433.92 MPa. Bending strength of composite is increased obviously compared with that of zirconia because the prestress of surface is compressive stress.展开更多
Functionally graded materials (FGMs) based on titanium-zirconia system have been prepared by powder metallurgical method. The graded interlayer number and the compositional distribution have been designed by elastic f...Functionally graded materials (FGMs) based on titanium-zirconia system have been prepared by powder metallurgical method. The graded interlayer number and the compositional distribution have been designed by elastic finite element method. The interfacial microstructure between layers, the combining state of phases between Ti and ZrO2 have been investigated by means of XRD (X-ray diffraction), SEM (scanning electron microscope), EDS (energy dispersive spectrometer) and so on. The co-existing region of Ti and ZrO2 has been determined by thermodynamic calculation to control the sintering atmosphere. The experimental results show that the joint between Ti and ZrO2 phases is physical in this composite and ZrO2 mainly exists as tetragonal phase. The microstructure of Ti-ZrO2 system FGM exhibits a transition from a zirconia particle dispersion in a titanium matrix to an inverse dispersion of titanium in zirconia. The gradient structure of titanium and zirconia can relieve thermal stress.展开更多
In this study, C,N,S-doped ZrO2 and a series of Eu doped C,N,S-ZrO2 photocatalysts were synthesized by a coprecipitation method using thiourea as the source of C, N and S and Eu（NO3）·6H2O as source of Eu. The m...In this study, C,N,S-doped ZrO2 and a series of Eu doped C,N,S-ZrO2 photocatalysts were synthesized by a coprecipitation method using thiourea as the source of C, N and S and Eu（NO3）·6H2O as source of Eu. The materials were characterized by X-ray dif-fraction （XRD）, Raman spectroscopy, Fourier transform infrared spectroscopy （FTIR）, UV-visible diffuse reflectance spectroscopy, scanning electron microscopy （SEM）/energy dispersive X-ray spectroscopy （EDX）, and transmission electron microscopy （TEM）. Indigo carmine （IC） was chosen as a model for organic pollutants and used to evaluate the photocatalytic performance of the photo-catalysts under simulated solar light. Commercial ZrO2 was used as a reference material. XRD and Raman results indicated the for-mation of both tetragonal and monoclinic phase ZrO2 with particle size ranging from 8–30 nm. Multi-element doping had a great in-fluence on the optical responses manifested as red shift in the absorption edge. The highest photocatalytic activity towards IC was observed for the Eu,C,N,S-doped ZrO2 （0.6 mol.%Eu） sample （k=1.09×10–2 min–1）. The commercial ZrO2 showed the lowest photo-degradation activity （k=5.83×10–4 min–1）. The results showed that the control of Eu doping in the C,N,S-ZrO2 was very important in reducing electron-hole recombination. The synergistic effect of Eu, C, N, and S in the ZrO2 matrix led to enhanced utilization of simulated solar energy for the degradation of IC through narrowing of bandgaps.展开更多
The effects of oxidation temperature and thickness of thermally grown oxide (TGO) on thermal stress distribution in thermal barrier coatings (TBCs) system are studied in the present paper.A typical TBC system is used:...The effects of oxidation temperature and thickness of thermally grown oxide (TGO) on thermal stress distribution in thermal barrier coatings (TBCs) system are studied in the present paper.A typical TBC system is used:air plasma sprayed (APS) Scandia,yttria-stabilized zirconia (ScYSZ) top coat (TC) and NiCrAlY bond coat (BC) deposited on the nickel super-alloy substrate.The behavior of BC oxidation was examined.Both the Numerical model and Finite Element (FE) method were used to analyze the stress distribution.The objective of this study is to provide important information for understanding the failure mechanism of TBCs at least in a qualitative way.展开更多
文摘基于通用力场(Universal Force Field,UFF)方法对二氧化锆纳米管进行结构优化,并计算得到了Zr-O键等效梁单元力学性质。通过等效梁单元模拟Zr-O键,质量单元模拟Zr原子和O原子,建立Zr NTs分子结构有限元模型。研究了手性、直径和长度对一端固定和两端固定结构固有频率的影响。结果表明:手性几乎不影响Zr NTs的固有频率;随着直径的增大,两端固定结构固有频率先增大后减小,一端固定结构固有频率增大;随着长度的增大,固有频率减小,二氧化锆纳米管在长径比小于3时,固有频率随长度的增加而急剧减小,长径比大于3时,固有频率的减小幅度随长度的增加明显降低。
基金Funded by the Science and Technique Research and Development Program of Shaanxi Province (No. 2007K06-13)the Science and Technique Program of Xi’an City (No. YF07061)
文摘Prestressed SUS316 fibers/ZrO2 composite was fabricated using tape casting. Causes of cracks were analyzed by classical thermo-elastic theory and finite element method in preparation process. An optimization design was carried out on SUS316 fibers’ arrangement modes by reducing residual thermal stress. Interface topography and element distribution of composite were observed, and bending strengths were tested. Results show that cracks are generated along the direction vertical to SUS316 fibers by axial thermal stress due to different thermal expansion coefficients between SUS316 fibers and zirconia, and the average cracking space is 2 mm. No macroscopic defect is found in composite with SUS316 fibers of sine distribution, and it has better interfacial binding force since interdiffusion between SUS316 and zirconia. Bending strengths of composite with 0°/0°lamination are anisotropic and that are 385.74 MPa and 500.7 MPa respectively, but that with 0°/90°lamination is isotropic and it is 433.92 MPa. Bending strength of composite is increased obviously compared with that of zirconia because the prestress of surface is compressive stress.
基金the National NatUralScience FoUndstion of China co.59872002).
文摘Functionally graded materials (FGMs) based on titanium-zirconia system have been prepared by powder metallurgical method. The graded interlayer number and the compositional distribution have been designed by elastic finite element method. The interfacial microstructure between layers, the combining state of phases between Ti and ZrO2 have been investigated by means of XRD (X-ray diffraction), SEM (scanning electron microscope), EDS (energy dispersive spectrometer) and so on. The co-existing region of Ti and ZrO2 has been determined by thermodynamic calculation to control the sintering atmosphere. The experimental results show that the joint between Ti and ZrO2 phases is physical in this composite and ZrO2 mainly exists as tetragonal phase. The microstructure of Ti-ZrO2 system FGM exhibits a transition from a zirconia particle dispersion in a titanium matrix to an inverse dispersion of titanium in zirconia. The gradient structure of titanium and zirconia can relieve thermal stress.
基金Project supported by the National Research Fund of South Africa
文摘In this study, C,N,S-doped ZrO2 and a series of Eu doped C,N,S-ZrO2 photocatalysts were synthesized by a coprecipitation method using thiourea as the source of C, N and S and Eu（NO3）·6H2O as source of Eu. The materials were characterized by X-ray dif-fraction （XRD）, Raman spectroscopy, Fourier transform infrared spectroscopy （FTIR）, UV-visible diffuse reflectance spectroscopy, scanning electron microscopy （SEM）/energy dispersive X-ray spectroscopy （EDX）, and transmission electron microscopy （TEM）. Indigo carmine （IC） was chosen as a model for organic pollutants and used to evaluate the photocatalytic performance of the photo-catalysts under simulated solar light. Commercial ZrO2 was used as a reference material. XRD and Raman results indicated the for-mation of both tetragonal and monoclinic phase ZrO2 with particle size ranging from 8–30 nm. Multi-element doping had a great in-fluence on the optical responses manifested as red shift in the absorption edge. The highest photocatalytic activity towards IC was observed for the Eu,C,N,S-doped ZrO2 （0.6 mol.%Eu） sample （k=1.09×10–2 min–1）. The commercial ZrO2 showed the lowest photo-degradation activity （k=5.83×10–4 min–1）. The results showed that the control of Eu doping in the C,N,S-ZrO2 was very important in reducing electron-hole recombination. The synergistic effect of Eu, C, N, and S in the ZrO2 matrix led to enhanced utilization of simulated solar energy for the degradation of IC through narrowing of bandgaps.
基金Foundation item:Program for New Century Excellent Talents in University(NCET-2006)Hunan Provincial Natural Science Foundation(10JJ2037)
文摘The effects of oxidation temperature and thickness of thermally grown oxide (TGO) on thermal stress distribution in thermal barrier coatings (TBCs) system are studied in the present paper.A typical TBC system is used:air plasma sprayed (APS) Scandia,yttria-stabilized zirconia (ScYSZ) top coat (TC) and NiCrAlY bond coat (BC) deposited on the nickel super-alloy substrate.The behavior of BC oxidation was examined.Both the Numerical model and Finite Element (FE) method were used to analyze the stress distribution.The objective of this study is to provide important information for understanding the failure mechanism of TBCs at least in a qualitative way.
