Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. Wire shaped Nimonic 80A samples are resistively ...Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. Wire shaped Nimonic 80A samples are resistively volume heated as part of a fast capacitor discharge circuit. Time resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe, voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers and the radiance temperature of the sample with a pyrometer. These measurements allow to determine heat of fusion as well as heat capacity and electrical resistivity at initial geometry of Nimonic 80A as a function of temperature in the solid and in the liquid phase up to 2400 K.展开更多
The paper proposes a simulated 3D Finite Element Model(FEM)for drilling of Nickel based super alloy known as Nimonic C-263.The Lagrangian finite element model-based simulations were performed to determine the thrust f...The paper proposes a simulated 3D Finite Element Model(FEM)for drilling of Nickel based super alloy known as Nimonic C-263.The Lagrangian finite element model-based simulations were performed to determine the thrust force,temperature generation,effective stress,and effective strain.The simulations were performed according to the L27 orthogonal array.A perfect plastic work piece was assumed,and the shape is considered to be cylindrical.The spindle speed,feed rate,and point angle were considered as the input parameters.The work piece was modeled by Johnson-Cook(JC)material model and tungsten carbide(WC)was chosen as the drill bit and the body was assumed to be rigid.The demonstrative results of the thrust force and the temperature at drill bit cutting edge were substantiated with the simulated results and a percentage error was observed within 10%.Further,simulated results of effective stress and strain were also observed.展开更多
Microstructural change,stress rupture property,deformation and fracture mechanisms of Nimonic 105 superalloy at 750℃have been studied.Experimental results showed that the stress rupture strength of the alloy at 750℃...Microstructural change,stress rupture property,deformation and fracture mechanisms of Nimonic 105 superalloy at 750℃have been studied.Experimental results showed that the stress rupture strength of the alloy at 750℃ for 10^(5)h is about 200 MPa.γ'precipitates and M_(23)C_(6)carbides grew gradually with prolonging the rupture time,while no significant change was observed in MC carbide morphology.After stress rupture test at 750℃ and 250 MPa for 23,341 h,a transition from spherical to cuboidal morphology of γ'precipitates was found,and nearly continuous chains of M_(23)C_(6)carbides formed on the grain boundary.Orowan looping and strongly coupled dislocation pairs cutting and microtwinning were the dominant deformation mechanisms at 750℃ and 350-450 MPa,while the main deformation mode was Orowan looping at 750℃ and 250 MPa.The failure of the alloy was mainly attributed to the nucleation,growth and interlinkage of voids.展开更多
A heterostructured electrocatalyst of small NiSe_(2) nanoparticles confined NiMoN nanorods(NiSe_(2)-NPs/NiMoN-NRs)is prepared to accelerate both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in...A heterostructured electrocatalyst of small NiSe_(2) nanoparticles confined NiMoN nanorods(NiSe_(2)-NPs/NiMoN-NRs)is prepared to accelerate both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in a same alkaline medium.The synergistic effects caused by the combination of merits derived from NiSe_(2) and NiMoN phases trigger an optimum electronic structure with high density of state at near Fermi level and enhance adsorption free energy,thereby resulting in excellent catalytic activities and strengthened working stability.The catalyst requires a low overpotential of 58 mV for HER and 241 mV for OER to reach 10 mA cm^(−2) in 1.0 M KOH electrolyte.A twoelectrode electrolyzer based on the developed catalyst shows outstanding cell voltage of 1.51 and 1.46 V to reach 10 mA cm^(−2) in 1.0 M and 30 wt%KOH solution at 25℃ for overall water splitting,respectively.In addition,the solardriven water splitting process delivers a high solar-to-H_(2) conversion efficiency of∼18.4%,impressively unveiling that the developed bifunctional catalyst is highly potential for overall water splitting to produce green hydrogen fuel.展开更多
基金This work was financially supported by the Austrian "Forschungsfrderungsgesellschaft mbH", Krntner Strasse 21-23, 1010 Vienna, under contract No. 810999.
文摘Nimonic 80A is a nickel-chromium alloy which is strengthened by additions of titanium and aluminium. The alloy is used for high temperature, high strength applications. Wire shaped Nimonic 80A samples are resistively volume heated as part of a fast capacitor discharge circuit. Time resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe, voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers and the radiance temperature of the sample with a pyrometer. These measurements allow to determine heat of fusion as well as heat capacity and electrical resistivity at initial geometry of Nimonic 80A as a function of temperature in the solid and in the liquid phase up to 2400 K.
文摘The paper proposes a simulated 3D Finite Element Model(FEM)for drilling of Nickel based super alloy known as Nimonic C-263.The Lagrangian finite element model-based simulations were performed to determine the thrust force,temperature generation,effective stress,and effective strain.The simulations were performed according to the L27 orthogonal array.A perfect plastic work piece was assumed,and the shape is considered to be cylindrical.The spindle speed,feed rate,and point angle were considered as the input parameters.The work piece was modeled by Johnson-Cook(JC)material model and tungsten carbide(WC)was chosen as the drill bit and the body was assumed to be rigid.The demonstrative results of the thrust force and the temperature at drill bit cutting edge were substantiated with the simulated results and a percentage error was observed within 10%.Further,simulated results of effective stress and strain were also observed.
基金the National Key Research and Develop plan,China(No.2016YFB0300203).
文摘Microstructural change,stress rupture property,deformation and fracture mechanisms of Nimonic 105 superalloy at 750℃have been studied.Experimental results showed that the stress rupture strength of the alloy at 750℃ for 10^(5)h is about 200 MPa.γ'precipitates and M_(23)C_(6)carbides grew gradually with prolonging the rupture time,while no significant change was observed in MC carbide morphology.After stress rupture test at 750℃ and 250 MPa for 23,341 h,a transition from spherical to cuboidal morphology of γ'precipitates was found,and nearly continuous chains of M_(23)C_(6)carbides formed on the grain boundary.Orowan looping and strongly coupled dislocation pairs cutting and microtwinning were the dominant deformation mechanisms at 750℃ and 350-450 MPa,while the main deformation mode was Orowan looping at 750℃ and 250 MPa.The failure of the alloy was mainly attributed to the nucleation,growth and interlinkage of voids.
基金supported by the Regional Leading Research Center Program(2019R1A5A8080326)BRL Program(2020R1A4A1018259)through the National Research Foundation funded by the Ministry of Science and ICT of the Republic of Korea.
文摘A heterostructured electrocatalyst of small NiSe_(2) nanoparticles confined NiMoN nanorods(NiSe_(2)-NPs/NiMoN-NRs)is prepared to accelerate both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in a same alkaline medium.The synergistic effects caused by the combination of merits derived from NiSe_(2) and NiMoN phases trigger an optimum electronic structure with high density of state at near Fermi level and enhance adsorption free energy,thereby resulting in excellent catalytic activities and strengthened working stability.The catalyst requires a low overpotential of 58 mV for HER and 241 mV for OER to reach 10 mA cm^(−2) in 1.0 M KOH electrolyte.A twoelectrode electrolyzer based on the developed catalyst shows outstanding cell voltage of 1.51 and 1.46 V to reach 10 mA cm^(−2) in 1.0 M and 30 wt%KOH solution at 25℃ for overall water splitting,respectively.In addition,the solardriven water splitting process delivers a high solar-to-H_(2) conversion efficiency of∼18.4%,impressively unveiling that the developed bifunctional catalyst is highly potential for overall water splitting to produce green hydrogen fuel.
