The cermet fuel element was achieved by dispersing the UO_(2)particles with or without tungsten(W)coating layer uniformly in the W matrix.It is considered to be a robust and secure fuel for use in nuclear thermal prop...The cermet fuel element was achieved by dispersing the UO_(2)particles with or without tungsten(W)coating layer uniformly in the W matrix.It is considered to be a robust and secure fuel for use in nuclear thermal propulsion in the near future.In this study,the effect of deposition temperature on the densification and grain refinement of the W coating layer was investigated.A high-density(19.24 g·cm^(-3))W layer with a uniform thickness(~10μm)and fine grains(~297 nm)was prepared by spouted-bed chemical vapor deposition.The prepared high-density,fine-grained W layer has the following advantages.It can prevent direct contact between fuel particles,resulting in a more uniform fuel distribution.In addition,it can decrease the reaction probability between the fuel kernel and H2,and prevent the release of fission products from the fuel kernel by extending the diffusion path at grain boundaries more efficiently.Moreover,the high-density,fine-grained W layer showed outstanding thermal and mechanical performance.Its average hardness and Young's modulus were approximately 7 and 200 GPa,respectively.The thermal conductivity of the W film was 101-124 W·m^(-1)·K^(-1)at 298-773 K.This work furthers our understanding of the potential application of the high-density,fine-grained W layer in nuclear thermal propulsion.展开更多
Carbon nanotubes （CNTs） were coated by tungsten layer using metal organic chemical vapor deposition process with tungsten hexacarbonyl as a precursor. The W-coated CNTs （W-CNTs） were dispersed into Cu powders by m...Carbon nanotubes （CNTs） were coated by tungsten layer using metal organic chemical vapor deposition process with tungsten hexacarbonyl as a precursor. The W-coated CNTs （W-CNTs） were dispersed into Cu powders by magnetic stirring process and then the mixed powders were consolidated by spark plasma sintering to fabricate W-CNTs/Cu composites. The CNTs/Cu composites were fabricated using the similafprocesses. The friction coefficient and mass wear loss of W-CNTs/Cu and CNTs/Cu composites were studied. The results showed that the W-CNT content, interfacial bonding situation, and applied load could influence the friction coefficient and wear loss of W-CNTs/Cu com- posites. When the W-CNT content was 1.0 wt.%, the W-CNTs/Cu composites got the minimum friction coefficient and wear loss, which were decreased by 72.1% and 47.6%, respectively, compared with pure Cu specimen. The friction coefficient and wear loss of W-CNTs/Cu composites were lower than those of CNTs/Cu composites, which was due to that the interracial bonding at （W-CNTs）-Cu interface was better than that at CNTs-Cu interface. The friction coefficient of composites did not vary obviously with increasing applied load, while the wear loss of composites increased significantly with the increase of applied load.展开更多
In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The ...In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The abrasive wear resistance of the composites layers were tested and compared with that of high chromium cast iron.The results show that the iron matrix composites with tungsten carbide particle have high hardness.The abrasive wear resistance of composites with tungsten carbide particle is higher than that of high chromium cast iron.The properties of the matrix materials have been improved remarkably.展开更多
基金financially supported by the Thorium Molten Salt Reactor Nuclear Energy System under the Strategic Pioneer Sci.&Tech.Project of the Chinese Academy of Sciences(XDA02030200)the Frontier Science Key Program of the Chinese Academy of Sciences(Grant No.QYZDY-SSW-JSC016)+2 种基金the Natural Science Foundation of Shanghai(Grant No.20ZR1468800 and 21ZR1476300)the Natural Science Foundation of Gansu province(Grant No.20JR5RE639)the Shanghai Pujiang Program(Grant No.19pj1431600)。
文摘The cermet fuel element was achieved by dispersing the UO_(2)particles with or without tungsten(W)coating layer uniformly in the W matrix.It is considered to be a robust and secure fuel for use in nuclear thermal propulsion in the near future.In this study,the effect of deposition temperature on the densification and grain refinement of the W coating layer was investigated.A high-density(19.24 g·cm^(-3))W layer with a uniform thickness(~10μm)and fine grains(~297 nm)was prepared by spouted-bed chemical vapor deposition.The prepared high-density,fine-grained W layer has the following advantages.It can prevent direct contact between fuel particles,resulting in a more uniform fuel distribution.In addition,it can decrease the reaction probability between the fuel kernel and H2,and prevent the release of fission products from the fuel kernel by extending the diffusion path at grain boundaries more efficiently.Moreover,the high-density,fine-grained W layer showed outstanding thermal and mechanical performance.Its average hardness and Young's modulus were approximately 7 and 200 GPa,respectively.The thermal conductivity of the W film was 101-124 W·m^(-1)·K^(-1)at 298-773 K.This work furthers our understanding of the potential application of the high-density,fine-grained W layer in nuclear thermal propulsion.
基金financially supported by the National Natural Science Foundation of China (No.50971020)National HighTech Research and Development Program of China (No.2009AA03Z116)
文摘Carbon nanotubes （CNTs） were coated by tungsten layer using metal organic chemical vapor deposition process with tungsten hexacarbonyl as a precursor. The W-coated CNTs （W-CNTs） were dispersed into Cu powders by magnetic stirring process and then the mixed powders were consolidated by spark plasma sintering to fabricate W-CNTs/Cu composites. The CNTs/Cu composites were fabricated using the similafprocesses. The friction coefficient and mass wear loss of W-CNTs/Cu and CNTs/Cu composites were studied. The results showed that the W-CNT content, interfacial bonding situation, and applied load could influence the friction coefficient and wear loss of W-CNTs/Cu com- posites. When the W-CNT content was 1.0 wt.%, the W-CNTs/Cu composites got the minimum friction coefficient and wear loss, which were decreased by 72.1% and 47.6%, respectively, compared with pure Cu specimen. The friction coefficient and wear loss of W-CNTs/Cu composites were lower than those of CNTs/Cu composites, which was due to that the interracial bonding at （W-CNTs）-Cu interface was better than that at CNTs-Cu interface. The friction coefficient of composites did not vary obviously with increasing applied load, while the wear loss of composites increased significantly with the increase of applied load.
文摘In this paper the Expendable Pattern Casting with dry sand Vacuum(EPC-V) process is used to manufacture iron matrix composites with tungsten carbide particle.Microstructures of the composites layers were analyzed.The abrasive wear resistance of the composites layers were tested and compared with that of high chromium cast iron.The results show that the iron matrix composites with tungsten carbide particle have high hardness.The abrasive wear resistance of composites with tungsten carbide particle is higher than that of high chromium cast iron.The properties of the matrix materials have been improved remarkably.
