The large-scale thick plates of Al2O3/ZrO2 (Y2O3) eutectics were prepared from the melts through combustion synthesis under high gravity. The plates contained randomly-orientated rod-shaped colonies with faceted str...The large-scale thick plates of Al2O3/ZrO2 (Y2O3) eutectics were prepared from the melts through combustion synthesis under high gravity. The plates contained randomly-orientated rod-shaped colonies with faceted structures and a triangular dispersion of orderly nano-submicron t-ZrO2 fibers, which were surrounded by the inter-colony regions with the coarse irregular-shaped t-ZrO2 phases. The increase in flexural strength was attributed to the small-size critical defect and high fracture toughness dependent on residual stress toughening, transformation toughening and microcrack toughening mechanisms.展开更多
针对光固化Al2O3陶瓷在脱脂烧结后易形成孔洞、力学性能差的问题,系统研究了石墨烯添加对陶瓷浆料流变性、沉降性、固化行为及烧结体力学性能的影响。采用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)对Al2O3粉体进行表面改性,并加入不同含...针对光固化Al2O3陶瓷在脱脂烧结后易形成孔洞、力学性能差的问题,系统研究了石墨烯添加对陶瓷浆料流变性、沉降性、固化行为及烧结体力学性能的影响。采用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)对Al2O3粉体进行表面改性,并加入不同含量的石墨烯,制备高固相、低粘度的光固化浆料。通过傅里叶红外光谱、旋转流变仪、沉降试验及Beer-Lambert模型分析,优化了浆料配方与光固化工艺参数。结果表明:当KH560含量为2.5wt%、石墨烯含量为0.01wt%时,浆料粘度最低、沉降分层最少;在曝光时间4 s条件下,添加0.01wt%石墨烯的浆料透射深度为382μm,临界曝光能量为44.3 m J/cm2。经1750℃烧结后,陶瓷零件致密度达99.7%,弯曲强度为27.61 MPa,维氏硬度为13.45GPa。石墨烯通过位阻效应及裂纹偏转机制有效促进了烧结致密化并改善了力学性能。本研究为光固化增材制造高致密、高性能氧化铝陶瓷提供了试验依据。展开更多
Y2O3-MgO nanocomposite ceramic,as a novel infrared window material,exhibits superior properties compared to traditional infrared window materials.To realize its engineering application in high-speed aircraft suc...Y2O3-MgO nanocomposite ceramic,as a novel infrared window material,exhibits superior properties compared to traditional infrared window materials.To realize its engineering application in high-speed aircraft such as unmanned aerial vehicles,the reliable joining between Y2O3-MgO nanocomposite ceramic and TC4 alloy is a key challenge.In this study,the surface of Y2O3-MgO nanocomposite ceramic was first clad in air using an Ag-CuO-Al2O3 filler,which achieved uniform spreading on the ceramic.Subsequently,vacuum brazing was successfully performed between the clad Y2O3-MgO nanocomposite ceramic and TC4 alloy using AgCu filler.The microstructure and mechanical properties of the brazed joints were studied in detail.The air-reactive cladding technique significantly improved wettability,reducing the wetting angle of the filler metal on Y2O3-MgO nanocomposite ceramic from 104°to 27°.The brazed joint interface treated with the Ag-CuO-Al2O3 cladding exhibited sound metallurgical bonding without defects.The main phases identified in the Y2O3-MgO ceramic-side reaction layer were Cu2Y2O5,Mg0.78Cu0.22O,and Y4Al2O9.Analysis and calculations reveal that Cu2Y2O5 and Mg0.78Cu0.22O are respectively formed by the reaction of CuO with Y2O3and MgO,while Y4Al2O9 results from the reaction between Al2O3 and Y2O3.The typical interfacial microstructure was:Y2O3-MgO/Cu2Y2O5+Mg0.78Cu0.22O+Y4Al2O9/CuxTi6-xO+Ag(s,s.)/Ti(s,s.)+Ti2Cu/TC4.The joint achieved a maximum shear strength of 66 MPa under optimal parameters of 24 mol%CuO in the cladding layer and a brazing parameters of 860°C for 20 min.展开更多
Industrial fly ash-derived SiO2aerogel with abundant mesopores has an excellent ability to support active ingredients for constructing efficient and stable catalyst in electrochemical CO2reduction reaction(CO_(2...Industrial fly ash-derived SiO2aerogel with abundant mesopores has an excellent ability to support active ingredients for constructing efficient and stable catalyst in electrochemical CO2reduction reaction(CO2RR).However,how to select and arrange active sites on its surface poses significant challenges due to its non-conductive nature.Here,we subtly designed and synthesized multi-component architectures to achieve the high efficiency of CO2RR to CO.The embedding of active and amorphous nitrogen-doped carbon(NC)nanosheets on the surface and inside of SiO2aerogel ensures the charge transport on the catalyst surface,and Er2O3improves dissociation of H2O,enabling the supply of protons for CO2RR.Simultaneously,Er2O3-induced defects/vacancies,nanoclusters coordinated with N on amorphous NC and single Ni in NC play crucial role in enhancing adsorption and activation of CO2.Consequently,the Ni-Er2O3/NC-SiO2catalyst exhibits the maintenance of FECOhigher than 95%over a wide potential window(-0.22 to-1.12 V vs.RHE)in a flow cell with gas-liquid-solid electrode.This work not only provides an atomistic understanding of nature of active sites in CO2RR but also contributes to the secondary utilization of industrial fly ash for a carbon-neutral future.展开更多
基金Acknowledgements: This work was supported by Natural Science Foundation of China (No. 50672131).
摘要The large-scale thick plates of Al2O3/ZrO2 (Y2O3) eutectics were prepared from the melts through combustion synthesis under high gravity. The plates contained randomly-orientated rod-shaped colonies with faceted structures and a triangular dispersion of orderly nano-submicron t-ZrO2 fibers, which were surrounded by the inter-colony regions with the coarse irregular-shaped t-ZrO2 phases. The increase in flexural strength was attributed to the small-size critical defect and high fracture toughness dependent on residual stress toughening, transformation toughening and microcrack toughening mechanisms.
摘要针对光固化Al2O3陶瓷在脱脂烧结后易形成孔洞、力学性能差的问题,系统研究了石墨烯添加对陶瓷浆料流变性、沉降性、固化行为及烧结体力学性能的影响。采用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)对Al2O3粉体进行表面改性,并加入不同含量的石墨烯,制备高固相、低粘度的光固化浆料。通过傅里叶红外光谱、旋转流变仪、沉降试验及Beer-Lambert模型分析,优化了浆料配方与光固化工艺参数。结果表明:当KH560含量为2.5wt%、石墨烯含量为0.01wt%时,浆料粘度最低、沉降分层最少;在曝光时间4 s条件下,添加0.01wt%石墨烯的浆料透射深度为382μm,临界曝光能量为44.3 m J/cm2。经1750℃烧结后,陶瓷零件致密度达99.7%,弯曲强度为27.61 MPa,维氏硬度为13.45GPa。石墨烯通过位阻效应及裂纹偏转机制有效促进了烧结致密化并改善了力学性能。本研究为光固化增材制造高致密、高性能氧化铝陶瓷提供了试验依据。
基金financial support from the National Natural Science Foundation of China(Grant Nos.U2167216,52504408,and 52475335)the China Postdoctoral Science Foundation Funded Project(Grant No.2024M754181)。
摘要Y2O3-MgO nanocomposite ceramic,as a novel infrared window material,exhibits superior properties compared to traditional infrared window materials.To realize its engineering application in high-speed aircraft such as unmanned aerial vehicles,the reliable joining between Y2O3-MgO nanocomposite ceramic and TC4 alloy is a key challenge.In this study,the surface of Y2O3-MgO nanocomposite ceramic was first clad in air using an Ag-CuO-Al2O3 filler,which achieved uniform spreading on the ceramic.Subsequently,vacuum brazing was successfully performed between the clad Y2O3-MgO nanocomposite ceramic and TC4 alloy using AgCu filler.The microstructure and mechanical properties of the brazed joints were studied in detail.The air-reactive cladding technique significantly improved wettability,reducing the wetting angle of the filler metal on Y2O3-MgO nanocomposite ceramic from 104°to 27°.The brazed joint interface treated with the Ag-CuO-Al2O3 cladding exhibited sound metallurgical bonding without defects.The main phases identified in the Y2O3-MgO ceramic-side reaction layer were Cu2Y2O5,Mg0.78Cu0.22O,and Y4Al2O9.Analysis and calculations reveal that Cu2Y2O5 and Mg0.78Cu0.22O are respectively formed by the reaction of CuO with Y2O3and MgO,while Y4Al2O9 results from the reaction between Al2O3 and Y2O3.The typical interfacial microstructure was:Y2O3-MgO/Cu2Y2O5+Mg0.78Cu0.22O+Y4Al2O9/CuxTi6-xO+Ag(s,s.)/Ti(s,s.)+Ti2Cu/TC4.The joint achieved a maximum shear strength of 66 MPa under optimal parameters of 24 mol%CuO in the cladding layer and a brazing parameters of 860°C for 20 min.
基金National Natural Science Foundation of China(22468034,22162019,22261040)Key Research and Development Project of Ordos(YF20240062)Science and Technology Projects of Inner Mongolia Autonomous Region(2021GG0195)。
摘要Industrial fly ash-derived SiO2aerogel with abundant mesopores has an excellent ability to support active ingredients for constructing efficient and stable catalyst in electrochemical CO2reduction reaction(CO2RR).However,how to select and arrange active sites on its surface poses significant challenges due to its non-conductive nature.Here,we subtly designed and synthesized multi-component architectures to achieve the high efficiency of CO2RR to CO.The embedding of active and amorphous nitrogen-doped carbon(NC)nanosheets on the surface and inside of SiO2aerogel ensures the charge transport on the catalyst surface,and Er2O3improves dissociation of H2O,enabling the supply of protons for CO2RR.Simultaneously,Er2O3-induced defects/vacancies,nanoclusters coordinated with N on amorphous NC and single Ni in NC play crucial role in enhancing adsorption and activation of CO2.Consequently,the Ni-Er2O3/NC-SiO2catalyst exhibits the maintenance of FECOhigher than 95%over a wide potential window(-0.22 to-1.12 V vs.RHE)in a flow cell with gas-liquid-solid electrode.This work not only provides an atomistic understanding of nature of active sites in CO2RR but also contributes to the secondary utilization of industrial fly ash for a carbon-neutral future.