The Ni-based Udemit720Li superalloy tends to form largeγ/γ'eutectic on grain boundaries(GBs)during solidification due to the addition of excessive Al and Ti elements,which provides convenience to study the effec...The Ni-based Udemit720Li superalloy tends to form largeγ/γ'eutectic on grain boundaries(GBs)during solidification due to the addition of excessive Al and Ti elements,which provides convenience to study the effect of carbide andγ/γ'eutectic on crack initiation and propagation during tensile process.In this paper,Udemit720Li superalloy samples were prepared by induction melting casting method,arc melting and suction casting method.The microstructure,tensile properties and mechanism of crack initiation and propagation in Ni-based superalloy fabricated by two methods are investigated.The results exhibitγ/γ'eutectic accelerates the stress concentration at GB and thus leads to premature fracture failure.The samples with grain-boundary eutectic have higher strain hardening rate,but their cumulative and local misorientations are lower.For samples without eutectic at GB,the primary crack initiates at grain-boundary carbide along GB and extends along GB or into grain matrix,and exhibits better deformation performance and dislocation storage capacity within grains.展开更多
In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallin...In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallinity, higher reducibility and surface acidity can be found on CeO2-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO2 catalyst with H2 can facilitate the adsorption of NH3 and NOx species, while the adsorbed NOx is basically inactive in the NH3-SCR reaction. Moreover, the reaction mechanism of the NH3-SCR reaction over CeO2 catalyst is not changed by H2 pretreatment,which is mainly under the control of Eley-Rideal（E-R） mechanism, The enhanced SCR performance of CeO2-H catalyst is mainly due to the promoted NH3 adsorption and the subsequent facilitation of SCR reaction through E-R pathway.展开更多
基金This work was supported by the USTB University of Science and Technology Beijing。
文摘The Ni-based Udemit720Li superalloy tends to form largeγ/γ'eutectic on grain boundaries(GBs)during solidification due to the addition of excessive Al and Ti elements,which provides convenience to study the effect of carbide andγ/γ'eutectic on crack initiation and propagation during tensile process.In this paper,Udemit720Li superalloy samples were prepared by induction melting casting method,arc melting and suction casting method.The microstructure,tensile properties and mechanism of crack initiation and propagation in Ni-based superalloy fabricated by two methods are investigated.The results exhibitγ/γ'eutectic accelerates the stress concentration at GB and thus leads to premature fracture failure.The samples with grain-boundary eutectic have higher strain hardening rate,but their cumulative and local misorientations are lower.For samples without eutectic at GB,the primary crack initiates at grain-boundary carbide along GB and extends along GB or into grain matrix,and exhibits better deformation performance and dislocation storage capacity within grains.
基金supported by National Natural Science Foundation of China(21546014)the National Natural Science Foundation of Shanghai,China(14ZR1417800)
文摘In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallinity, higher reducibility and surface acidity can be found on CeO2-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO2 catalyst with H2 can facilitate the adsorption of NH3 and NOx species, while the adsorbed NOx is basically inactive in the NH3-SCR reaction. Moreover, the reaction mechanism of the NH3-SCR reaction over CeO2 catalyst is not changed by H2 pretreatment,which is mainly under the control of Eley-Rideal（E-R） mechanism, The enhanced SCR performance of CeO2-H catalyst is mainly due to the promoted NH3 adsorption and the subsequent facilitation of SCR reaction through E-R pathway.
