A characteristic CaO-Al2O3-SiO2 based foam ceramic was prepared by melt-foaming with solid wastes as main raw materials.The similarity to sandwich hole wall microstructure of this novel thermal insulating material was...A characteristic CaO-Al2O3-SiO2 based foam ceramic was prepared by melt-foaming with solid wastes as main raw materials.The similarity to sandwich hole wall microstructure of this novel thermal insulating material was presented and the relationships between this unique microstructure and porosity,density,thermal conductivity and strength were discussed.Comparing the measured and theoretical values with that of the traditional foam ceramic,it can be found that,for the matching of fine skeleton with hole wall,this original sandwich structure can reduce thermal conductivity and increase flexural strength effectively.展开更多
In the present study,WB 2（N） films are fabricated on silicon and YG8 substrates at different N 2 pressures by reactive magnetron sputtering.The influence of N 2 partial pressure（P （N2）） on the film microstructur...In the present study,WB 2（N） films are fabricated on silicon and YG8 substrates at different N 2 pressures by reactive magnetron sputtering.The influence of N 2 partial pressure（P （N2）） on the film microstructure and characteristics is studied systematically,including the chemical composition,crystalline structure,residual stress,surface roughness as well as the surface and the cross-section morphology.Meanwhile,nano-indentation and ball-on-disk tribometer are performed to analyze the mechanical and tribological properties of the films.The results show that the addition of nitrogen apparently leads to the change of the structure from（1 0 1） to（0 0 1） orientation then to the amorphous structure with the formation of BN phase.And the addition of nitrogen can greatly refine the grain size and microstructure of the films.Furthermore,the residual stress of the film is also found to change from tensile to compressive stress as a function of P （N2）,and the compressive stress increases with P （N2）,The WB 2（N） films with small nitrogen content,which are deposited at P （N2） of 0.004 and 0.006 Pa,exhibit better mechanical,tribological and corrosion properties than those of other films.Further increase of nitrogen content accelerates the formation of BN phase and fast decreases the film hardness.In addition,the large N 2 partial pressure gives rise to the target poisoning accompanied by the increase of the target voltage and the decrease of the deposition rate.展开更多
The influence of the bilayer number on the microstructure,mechanical properties,adhesion strength and tribological behaviors of the WB_(2)/Cr multilayer films was systematically investigated in the present study.Five ...The influence of the bilayer number on the microstructure,mechanical properties,adhesion strength and tribological behaviors of the WB_(2)/Cr multilayer films was systematically investigated in the present study.Five groups of WB_(2)/Cr films with the same modulation ratio were synthesized by magnetron sputtering technique.The crystalline structure of the films was determined by X-ray diffraction.The morphologies and the microstructure of the films were observed by scanning electron microscopy,atomic force microscopy and transmission electron microscopy.Furthermore,Nano indenter,scratch tester and ball-on-disc tribometer were used to evaluate the mechanical and tribological properties.As bilayer numbers varied from 5 to 40,the hardness increased first and then decreased with the maximum hardness of 33.9 GPa when the bilayer number is 30.The H/E^(*)and H^(3)/E^(*2)values calculated to evaluate the fracture toughness showed the similar changing trend with hardness.The adhesion strength reached the maximum of 67 N when the bilayer number is 30.The surface roughness and friction coefficient decreased with increasing bilayer number.The wear mechanism was also investigated,and the results suggested that the multilayer film with bilayer number of 30 exhibited the best wear resistance(1.78×10^(–7)mm^(3)/Nm),benefiting from the contribution of high hardness,fracture toughness and adhesion strength.展开更多
For deep geological disposal of high-level radioactive waste(HLW)in granite,the temperature on the HLW canisters is commonly designed to be lower than100fiC.This criterion dictates the dimension of the repository.Base...For deep geological disposal of high-level radioactive waste(HLW)in granite,the temperature on the HLW canisters is commonly designed to be lower than100fiC.This criterion dictates the dimension of the repository.Based on the concept of HLW disposal in vertical boreholes,thermal process in the nearfield(host rock and buffer)surrounding HLW canisters has been simulated by using different methods.The results are drawn as follows:(a)the initial heat power of HLW canisters is the most important and sensitive parameter for evolution of temperaturefield;(b)the thermal properties and variations of the host rock,the engineered buffer,and possible gaps between canister and buffer and host rock are the additional key factors governing the heat transformation;(c)the gaps width and thefilling by water or air determine the temperature offsets between them.展开更多
基金financial support of the project from the National Natural Science Foundation of China(51172016)。
文摘A characteristic CaO-Al2O3-SiO2 based foam ceramic was prepared by melt-foaming with solid wastes as main raw materials.The similarity to sandwich hole wall microstructure of this novel thermal insulating material was presented and the relationships between this unique microstructure and porosity,density,thermal conductivity and strength were discussed.Comparing the measured and theoretical values with that of the traditional foam ceramic,it can be found that,for the matching of fine skeleton with hole wall,this original sandwich structure can reduce thermal conductivity and increase flexural strength effectively.
基金supported by the National Key Basic Research Program of China (973 Program,No.2012CB625100)the Natural Science Foundation of Liaoning Province of China (No.2013020093)
文摘In the present study,WB 2（N） films are fabricated on silicon and YG8 substrates at different N 2 pressures by reactive magnetron sputtering.The influence of N 2 partial pressure（P （N2）） on the film microstructure and characteristics is studied systematically,including the chemical composition,crystalline structure,residual stress,surface roughness as well as the surface and the cross-section morphology.Meanwhile,nano-indentation and ball-on-disk tribometer are performed to analyze the mechanical and tribological properties of the films.The results show that the addition of nitrogen apparently leads to the change of the structure from（1 0 1） to（0 0 1） orientation then to the amorphous structure with the formation of BN phase.And the addition of nitrogen can greatly refine the grain size and microstructure of the films.Furthermore,the residual stress of the film is also found to change from tensile to compressive stress as a function of P （N2）,and the compressive stress increases with P （N2）,The WB 2（N） films with small nitrogen content,which are deposited at P （N2） of 0.004 and 0.006 Pa,exhibit better mechanical,tribological and corrosion properties than those of other films.Further increase of nitrogen content accelerates the formation of BN phase and fast decreases the film hardness.In addition,the large N 2 partial pressure gives rise to the target poisoning accompanied by the increase of the target voltage and the decrease of the deposition rate.
基金supported by the National Natural Science Foundation of China(No.51701157)。
文摘The influence of the bilayer number on the microstructure,mechanical properties,adhesion strength and tribological behaviors of the WB_(2)/Cr multilayer films was systematically investigated in the present study.Five groups of WB_(2)/Cr films with the same modulation ratio were synthesized by magnetron sputtering technique.The crystalline structure of the films was determined by X-ray diffraction.The morphologies and the microstructure of the films were observed by scanning electron microscopy,atomic force microscopy and transmission electron microscopy.Furthermore,Nano indenter,scratch tester and ball-on-disc tribometer were used to evaluate the mechanical and tribological properties.As bilayer numbers varied from 5 to 40,the hardness increased first and then decreased with the maximum hardness of 33.9 GPa when the bilayer number is 30.The H/E^(*)and H^(3)/E^(*2)values calculated to evaluate the fracture toughness showed the similar changing trend with hardness.The adhesion strength reached the maximum of 67 N when the bilayer number is 30.The surface roughness and friction coefficient decreased with increasing bilayer number.The wear mechanism was also investigated,and the results suggested that the multilayer film with bilayer number of 30 exhibited the best wear resistance(1.78×10^(–7)mm^(3)/Nm),benefiting from the contribution of high hardness,fracture toughness and adhesion strength.
文摘For deep geological disposal of high-level radioactive waste(HLW)in granite,the temperature on the HLW canisters is commonly designed to be lower than100fiC.This criterion dictates the dimension of the repository.Based on the concept of HLW disposal in vertical boreholes,thermal process in the nearfield(host rock and buffer)surrounding HLW canisters has been simulated by using different methods.The results are drawn as follows:(a)the initial heat power of HLW canisters is the most important and sensitive parameter for evolution of temperaturefield;(b)the thermal properties and variations of the host rock,the engineered buffer,and possible gaps between canister and buffer and host rock are the additional key factors governing the heat transformation;(c)the gaps width and thefilling by water or air determine the temperature offsets between them.
