Benefiting from excellent mechanical properties and low density,cellular ceramic structures(CCSs)are competitive candidates as structural components.However,inherent brittleness from strong chemical bonds among atoms ...Benefiting from excellent mechanical properties and low density,cellular ceramic structures(CCSs)are competitive candidates as structural components.However,inherent brittleness from strong chemical bonds among atoms extremely impeded CCSs'application.Natural materials occupied outstanding strength and toughness simultaneously due to the dual-phase interpenetrated structure.Inspired by natural materials,it was proposed to fabricate coating covered and fulfilled polyurea/CCS interpenetrated composites(C/CCSs and B/CCSs)to circumvent the brittleness of 3D-printed Al_(2)O_(3)CCSs.It was demonstrated that polyurea coating had less effect on the compressive strength of C/CCSs but tremendously improved their energy-absorbing ability.The energy-absorbing ability of C/CCSs was improved from26.48-52.57 kJ·m^(-3)of CCSs to 1.04-1.89 MJ·m^(-3)because of the extended plateau stage.Furthermore,compressive strength and energy-absorbing ability of B/CCSs were strengthened to 1.33-1.36 and 2.84-4.61 times of C/CCSs,respectively.Besides,failure mode of C/CCSs changed from localized deformation to fracturing entirely with the increase in relative density of CCSs inside,which was the same as that of CCSs.However,with the help of polyurea coating,C/CCSs were still intact at strains up to60%,which would neve r fail catastrophically as CCSs at low strains.B/CCSs tended to fracture as a whole,which was not influenced by relative density of pristine CCSs.It was believed that this work provided a creative way to circumvent the brittleness of CCSs and improve their mechanical performances.展开更多
Fe-based powder with a composition of Fe_（42.87）Cr_（15.98）Mo_（16.33）C_（15.94）B_（8.88）（at.%）was used to fabricate coatings by high-velocity oxygen fuel spraying.The effects of the spraying parameters on the...Fe-based powder with a composition of Fe_（42.87）Cr_（15.98）Mo_（16.33）C_（15.94）B_（8.88）（at.%）was used to fabricate coatings by high-velocity oxygen fuel spraying.The effects of the spraying parameters on the microstructure and the wear properties of the Fe-based alloy coatings were systematically studied.The results showed that the obtained Fe-based coatings with a thickness of about 400μm consisted of a large-volume amorphous phase and some nanocrystals.With increasing the fuel and oxygen flow rates,the porosity of the obtained coatings decreased.The coating deposited under optimized parameters exhibited the lowest porosity of 2.8%.The excellent wear resistance of this coating was attributed to the properties of the amorphous matrix and the presence of nanocrystals homogeneously distributed within the matrix.The wear mechanism of the coatings was discussed on the basis of observations of the worn surfaces.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52275310)the Open Project of State Key Laboratory of Explosion Science and Technology(No.QNKT22-15)the BIT Research and Innovation Promoting Project(No.2022YCX020)。
文摘Benefiting from excellent mechanical properties and low density,cellular ceramic structures(CCSs)are competitive candidates as structural components.However,inherent brittleness from strong chemical bonds among atoms extremely impeded CCSs'application.Natural materials occupied outstanding strength and toughness simultaneously due to the dual-phase interpenetrated structure.Inspired by natural materials,it was proposed to fabricate coating covered and fulfilled polyurea/CCS interpenetrated composites(C/CCSs and B/CCSs)to circumvent the brittleness of 3D-printed Al_(2)O_(3)CCSs.It was demonstrated that polyurea coating had less effect on the compressive strength of C/CCSs but tremendously improved their energy-absorbing ability.The energy-absorbing ability of C/CCSs was improved from26.48-52.57 kJ·m^(-3)of CCSs to 1.04-1.89 MJ·m^(-3)because of the extended plateau stage.Furthermore,compressive strength and energy-absorbing ability of B/CCSs were strengthened to 1.33-1.36 and 2.84-4.61 times of C/CCSs,respectively.Besides,failure mode of C/CCSs changed from localized deformation to fracturing entirely with the increase in relative density of CCSs inside,which was the same as that of CCSs.However,with the help of polyurea coating,C/CCSs were still intact at strains up to60%,which would neve r fail catastrophically as CCSs at low strains.B/CCSs tended to fracture as a whole,which was not influenced by relative density of pristine CCSs.It was believed that this work provided a creative way to circumvent the brittleness of CCSs and improve their mechanical performances.
基金Item Sponsored by National Natural Science Foundation of China(51205001)Key Project of Natural Science of Education Department of Anhui Province of China(KJ2014A023)Scientific Research Starting Foundation of Anhui Polytechnic University of China(2012YQQ006)
文摘Fe-based powder with a composition of Fe_（42.87）Cr_（15.98）Mo_（16.33）C_（15.94）B_（8.88）（at.%）was used to fabricate coatings by high-velocity oxygen fuel spraying.The effects of the spraying parameters on the microstructure and the wear properties of the Fe-based alloy coatings were systematically studied.The results showed that the obtained Fe-based coatings with a thickness of about 400μm consisted of a large-volume amorphous phase and some nanocrystals.With increasing the fuel and oxygen flow rates,the porosity of the obtained coatings decreased.The coating deposited under optimized parameters exhibited the lowest porosity of 2.8%.The excellent wear resistance of this coating was attributed to the properties of the amorphous matrix and the presence of nanocrystals homogeneously distributed within the matrix.The wear mechanism of the coatings was discussed on the basis of observations of the worn surfaces.
