The novel ceramic/metal composite materials were successfully fabricated by combustion synthesis in high gravity field.In this paper,the Ti-B_(4)C was selected as the main combustion reaction system to obtain TiB_(2)-...The novel ceramic/metal composite materials were successfully fabricated by combustion synthesis in high gravity field.In this paper,the Ti-B_(4)C was selected as the main combustion reaction system to obtain TiB_(2)-TiC ceramic substrate,and the 1Cr18Ni9Ti stainless steel was selected as the metal substrate.It was found that the TiB_(2)-TiC/1Cr18Ni9Ti composite materials exhibited continuously graded composition and hybrid microstructure.The TiC1-x carbides and TiB_(2)platelets decreased gradually in size and volume fraction from the ceramic to stainless steel.Due to the rapid action of thermal explosion as well as the dissolution of the molten stainless steel into TiB_(2)-TiC liquid,the diffusion-controlled concentration gradient from the ceramic liquid to the alloy liquid was observed.Finally,as a result of the rapid sequent solidification of the ceramic liquid and the melt alloy surface,the laminated composite materials were achieved in multilevel,scale-span hybrid microstructure.展开更多
To improve the survivability of orbiting spacecraft against space debris impacts,we propose an impact damage assessment method.First,a multi-area damage mining model,which can describe damages in different spatial lay...To improve the survivability of orbiting spacecraft against space debris impacts,we propose an impact damage assessment method.First,a multi-area damage mining model,which can describe damages in different spatial layers,is built based on an infrared thermal image sequence.Subsequently,to identify different impact damage types from infrared image data effectively,the variational Bayesian inference is used to solve for the parameters in the model.Then,an image-processing framework is proposed to eliminate variational Bayesian errors and compare locations of different damage types.It includes an image segmentation algorithm with an energy function and an image fusion method with sparse representation.In the experiment,the proposed method is used to evaluate the complex damages caused by the impact of the secondary debris cloud on the rear wall of the typical Whipple shield configuration.Experimental results show that it can effectively identify and evaluate the complex damage caused by hypervelocity impact,including surface and internal defects.展开更多
Since the first artificial satellite was launched in 1957,increasing human space activities have led to a deteriorating space debris environment.A huge amount of tiny space debris(from millimeter to micron level)appea...Since the first artificial satellite was launched in 1957,increasing human space activities have led to a deteriorating space debris environment.A huge amount of tiny space debris(from millimeter to micron level)appears in the Earth’s orbit,and its hypervelocity impact will cause serious damage to the structure and functional units of the spacecraft,including cabin’s outer surface,thermal barrier materials,thermal con-trol coatings,solar panels,pipes,and cables.To ensure the safe operation of spacecraft and the completion of space missions.展开更多
基金sponsored by the National Natural Science Foundation of China(Grant No.51072229).
文摘The novel ceramic/metal composite materials were successfully fabricated by combustion synthesis in high gravity field.In this paper,the Ti-B_(4)C was selected as the main combustion reaction system to obtain TiB_(2)-TiC ceramic substrate,and the 1Cr18Ni9Ti stainless steel was selected as the metal substrate.It was found that the TiB_(2)-TiC/1Cr18Ni9Ti composite materials exhibited continuously graded composition and hybrid microstructure.The TiC1-x carbides and TiB_(2)platelets decreased gradually in size and volume fraction from the ceramic to stainless steel.Due to the rapid action of thermal explosion as well as the dissolution of the molten stainless steel into TiB_(2)-TiC liquid,the diffusion-controlled concentration gradient from the ceramic liquid to the alloy liquid was observed.Finally,as a result of the rapid sequent solidification of the ceramic liquid and the melt alloy surface,the laminated composite materials were achieved in multilevel,scale-span hybrid microstructure.
基金supported by the National Natural Science Foundation of China(No.61873305)the Applied Basic Research Program of Sichuan Province,China(Nos.2018JY0410and 2019YJ0199)。
文摘To improve the survivability of orbiting spacecraft against space debris impacts,we propose an impact damage assessment method.First,a multi-area damage mining model,which can describe damages in different spatial layers,is built based on an infrared thermal image sequence.Subsequently,to identify different impact damage types from infrared image data effectively,the variational Bayesian inference is used to solve for the parameters in the model.Then,an image-processing framework is proposed to eliminate variational Bayesian errors and compare locations of different damage types.It includes an image segmentation algorithm with an energy function and an image fusion method with sparse representation.In the experiment,the proposed method is used to evaluate the complex damages caused by the impact of the secondary debris cloud on the rear wall of the typical Whipple shield configuration.Experimental results show that it can effectively identify and evaluate the complex damage caused by hypervelocity impact,including surface and internal defects.
文摘Since the first artificial satellite was launched in 1957,increasing human space activities have led to a deteriorating space debris environment.A huge amount of tiny space debris(from millimeter to micron level)appears in the Earth’s orbit,and its hypervelocity impact will cause serious damage to the structure and functional units of the spacecraft,including cabin’s outer surface,thermal barrier materials,thermal con-trol coatings,solar panels,pipes,and cables.To ensure the safe operation of spacecraft and the completion of space missions.
