Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanopa...Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanoparticles were dispersed in the electrodeposited nanocrystalline Ni grains （with a size range of 10-30 nm）. The isothermal oxidation behaviours of Ni-CeO2 nanocomposite coatings with two different CeO2 particles contents and the electrodeposited pure Ni coating were comparatively investigated in order to elucidate the effect of CeO2 at different temperatures and also CeO2 contents on the oxidation behaviour of Ni-CeO2 nanocomposite coatings. The results show that the as-codeposited Ni-CeO2 nanocomposite coatings have a superior oxidation resistance compared with the electrodeposited pure Ni coating at 800 °C due to the codeposited CeO2 nanoparticles blocking the outward diffusion of nickel along the grain boundaries. However, the effects of CeO2 particles on the oxidation resistance significantly decrease at 1050 °C and 1150 °C due to the outward-volume diffusion of nickel controlling the oxidation growth mechanism, and the content of CeO2 has little influence on the oxidation.展开更多
By using CeO2 particles instead of part of Al2O3 particles as filler, the CeO2 was successfully entrapped into the outer layer of the chromizing coatings on the as-deposited nanocrystalline （NC） and microcrystalline...By using CeO2 particles instead of part of Al2O3 particles as filler, the CeO2 was successfully entrapped into the outer layer of the chromizing coatings on the as-deposited nanocrystalline （NC） and microcrystalline （MC） Ni films using a conventional pack-cementation method at 800 °C. For comparison, chromizing was also performed under the same condition on MC Ni film using Al2O3 as filler without CeO2 particles. SEM/EDX and TEM results indicate that the refinement of Ni grain and CeO2 entrapped into the chromizing coatings refine the grain of the chromizing coating. Oxidation at 900 °C indicates that compared with the CeO2-free chromizing coating, the CeO2-dispersed chromizing coating exhibits an increased oxidation resistance. For the CeO2-dispersed chromizing coating, the refinement of Ni grain size significantly decreases the transient-oxidation scaling rate of the chromizing coatings. Together with this, the CeO2-dispersed chromizing coating formed on NC Ni exhibits a better oxidation resistance.展开更多
Based on the serial-parallel model of single-layer board and the lamination theory, the forces exerted on different layers of the high-pressure hose and the resulting deformations were analyzed when the hose was radia...Based on the serial-parallel model of single-layer board and the lamination theory, the forces exerted on different layers of the high-pressure hose and the resulting deformations were analyzed when the hose was radially stretched. An equation was proposed to calculate the anisotropic elastic constant of the composite layer with the wound steel wires. Furthermore, the finite element analysis （FEA） model of the high-pressure hose was established, followed by a simulation of the forces that act on different layers, and their deformations. The simulation results show that the stress imposed on the inner reinforced layer and external reinforced layer of the high-pressure hose are approximately 150 MPa and 115 MPa, respectively, in the presence of inner pressure. The stress of the rubber coating and polyethylene coating is lower. The lowest stress occurs on the inner surface of the high-pressure hose and the rubber coating between the two composite layers. The deformation of the rubber layer in the inner surface of the high-pressure hose decreases gradually along the radial direction from the inner surface to the external surface. The deformation of the reinforced composite layer is less than that of the external surface of the rubber coating. The equivalent stress of the reinforced composite layer is higher than that caused by the inner pressure, due to the presence of both inner pressure and axial tension.展开更多
Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapph...Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapphire optical dome coated with yttrium oxide by a radio frequency mag- netron sputtering method. The emissivity of sapphire coated with Y203 films is studied by both numerical and experi- mental methods. The results indicate that the emissivity of sapphire substrate is reduced effectively with increasing the thickness of the Y203 film. In addition, a finite element model is developed to simulate the radiation intensity of the optical dome. The thermal responses indicate that the max- imum temperature is reduced apparently compared with the uncoated sapphire as Y203 film thicknesses increase. The average irradiance distribution at different film thicknesses with time shows that the self-thermal radiation disturbance of sapphire optical dome delays 0.93 s when the thickness of Y203 film is 200μm, which can guarantee the dome works properly and effectively even in a harsh environment.展开更多
基金Project(11531319)supported by Scientific Research Fund of Heilongjiang Provincial Education Department,China
文摘Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanoparticles were dispersed in the electrodeposited nanocrystalline Ni grains （with a size range of 10-30 nm）. The isothermal oxidation behaviours of Ni-CeO2 nanocomposite coatings with two different CeO2 particles contents and the electrodeposited pure Ni coating were comparatively investigated in order to elucidate the effect of CeO2 at different temperatures and also CeO2 contents on the oxidation behaviour of Ni-CeO2 nanocomposite coatings. The results show that the as-codeposited Ni-CeO2 nanocomposite coatings have a superior oxidation resistance compared with the electrodeposited pure Ni coating at 800 °C due to the codeposited CeO2 nanoparticles blocking the outward diffusion of nickel along the grain boundaries. However, the effects of CeO2 particles on the oxidation resistance significantly decrease at 1050 °C and 1150 °C due to the outward-volume diffusion of nickel controlling the oxidation growth mechanism, and the content of CeO2 has little influence on the oxidation.
基金Project(11531319)supported by Scientific Research Fund of Heilongjiang Provincial Education Department,China
文摘By using CeO2 particles instead of part of Al2O3 particles as filler, the CeO2 was successfully entrapped into the outer layer of the chromizing coatings on the as-deposited nanocrystalline （NC） and microcrystalline （MC） Ni films using a conventional pack-cementation method at 800 °C. For comparison, chromizing was also performed under the same condition on MC Ni film using Al2O3 as filler without CeO2 particles. SEM/EDX and TEM results indicate that the refinement of Ni grain and CeO2 entrapped into the chromizing coatings refine the grain of the chromizing coating. Oxidation at 900 °C indicates that compared with the CeO2-free chromizing coating, the CeO2-dispersed chromizing coating exhibits an increased oxidation resistance. For the CeO2-dispersed chromizing coating, the refinement of Ni grain size significantly decreases the transient-oxidation scaling rate of the chromizing coatings. Together with this, the CeO2-dispersed chromizing coating formed on NC Ni exhibits a better oxidation resistance.
文摘Based on the serial-parallel model of single-layer board and the lamination theory, the forces exerted on different layers of the high-pressure hose and the resulting deformations were analyzed when the hose was radially stretched. An equation was proposed to calculate the anisotropic elastic constant of the composite layer with the wound steel wires. Furthermore, the finite element analysis （FEA） model of the high-pressure hose was established, followed by a simulation of the forces that act on different layers, and their deformations. The simulation results show that the stress imposed on the inner reinforced layer and external reinforced layer of the high-pressure hose are approximately 150 MPa and 115 MPa, respectively, in the presence of inner pressure. The stress of the rubber coating and polyethylene coating is lower. The lowest stress occurs on the inner surface of the high-pressure hose and the rubber coating between the two composite layers. The deformation of the rubber layer in the inner surface of the high-pressure hose decreases gradually along the radial direction from the inner surface to the external surface. The deformation of the reinforced composite layer is less than that of the external surface of the rubber coating. The equivalent stress of the reinforced composite layer is higher than that caused by the inner pressure, due to the presence of both inner pressure and axial tension.
文摘Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapphire optical dome coated with yttrium oxide by a radio frequency mag- netron sputtering method. The emissivity of sapphire coated with Y203 films is studied by both numerical and experi- mental methods. The results indicate that the emissivity of sapphire substrate is reduced effectively with increasing the thickness of the Y203 film. In addition, a finite element model is developed to simulate the radiation intensity of the optical dome. The thermal responses indicate that the max- imum temperature is reduced apparently compared with the uncoated sapphire as Y203 film thicknesses increase. The average irradiance distribution at different film thicknesses with time shows that the self-thermal radiation disturbance of sapphire optical dome delays 0.93 s when the thickness of Y203 film is 200μm, which can guarantee the dome works properly and effectively even in a harsh environment.
