Recently,the presentation of the metal-ceramic composite structure design provides an alternative idea for the improvement of components service performance,while conventional methods for joining metals and ceramics h...Recently,the presentation of the metal-ceramic composite structure design provides an alternative idea for the improvement of components service performance,while conventional methods for joining metals and ceramics have to involve a high heat input.However,due to the low melting point of magnesium alloys,the magnesium alloys-ceramics joining system necessitates a low joining temperature.Ultrasonic vibrations can induce numerous defects in the solid matrix,which can effectively promote atomic diffusion and metallurgical bonding between solid-phase interfaces at low temperatures.Thus,ultrasonic-assisted bonding is a highly promising method for achieving rapid and reliable joining between metals and ceramics without the use of interlayers.In this study,the direct bonding of AZ31B alloy with ZrO_(2) ceramic was successfully achieved at 200℃.A polycrystal spinel MgAl_(2)O_(4) with an average thickness of 55 nm was identified at the AZ31B/ZrO_(2) interface.The average shear strength of joints reached 30.47 MPa.Furthermore,the dynamic recrystallization of AZ31B and the oxygendepletion behavior of ZrO_(2) during the bonding process were characterized to illustrate the contribution of ultrasonic vibration to joint bonding.Consequently,the solid interfacial sono-oxidation reaction is proposed to discuss the bonding mechanism of the joint in detail.展开更多
LiBH_(4) containing 18.5 wt.%H_(2) is an attractive high-capacity hydrogen storage material,however,it suffers from high operation temperature and poor reversibility.Herein,a novel and low-cost bifunctional additive,w...LiBH_(4) containing 18.5 wt.%H_(2) is an attractive high-capacity hydrogen storage material,however,it suffers from high operation temperature and poor reversibility.Herein,a novel and low-cost bifunctional additive,waxberry-like Fe_(3)O_(4) secondary nanospheres assembled from ultrafine primary Fe_(3)O_(4) nanoparticles,is synthesized,which exhibits significant destabilization and bidirectional catalyzation towards(de)hydrogenation of LiBH_(4).With an optimized addition of 30 wt.% waxberry-like Fe_(3)O_(4),the system initiated dehydrogenation below 100℃ and released a total of 8.1 wt.%H_(2) to 400℃.After 10 cycles,a capacity retention of 70% was achieved,greatly superior to previously reported oxides-modified systems.The destabilizing and catalyzing mechanisms of waxberry-like Fe_(3)O_(4) on LiBH_(4) were systematically analyzed by phase and microstructural evolutions during dehydrogenation and hydrogenation cycling as well as density functional theory(DFT)calculations.The present work provides new insights in developing advanced nano-additives with unique structural and multifunctional designs towards LiBH4 hydrogen storage.展开更多
基金supported by the Shandong Provincial Natural Science Foundation(ZR2023ME111).
文摘Recently,the presentation of the metal-ceramic composite structure design provides an alternative idea for the improvement of components service performance,while conventional methods for joining metals and ceramics have to involve a high heat input.However,due to the low melting point of magnesium alloys,the magnesium alloys-ceramics joining system necessitates a low joining temperature.Ultrasonic vibrations can induce numerous defects in the solid matrix,which can effectively promote atomic diffusion and metallurgical bonding between solid-phase interfaces at low temperatures.Thus,ultrasonic-assisted bonding is a highly promising method for achieving rapid and reliable joining between metals and ceramics without the use of interlayers.In this study,the direct bonding of AZ31B alloy with ZrO_(2) ceramic was successfully achieved at 200℃.A polycrystal spinel MgAl_(2)O_(4) with an average thickness of 55 nm was identified at the AZ31B/ZrO_(2) interface.The average shear strength of joints reached 30.47 MPa.Furthermore,the dynamic recrystallization of AZ31B and the oxygendepletion behavior of ZrO_(2) during the bonding process were characterized to illustrate the contribution of ultrasonic vibration to joint bonding.Consequently,the solid interfacial sono-oxidation reaction is proposed to discuss the bonding mechanism of the joint in detail.
基金supported by the National Natural Science Foundation of China(No.52071287)the Natural Science Foundation of Zhejiang Province(No.LZ23E010002)the Basic and Applied Basic Research Foundation of Guangdong Province(Nos.2021A1515110676,2022A1515011832).
文摘LiBH_(4) containing 18.5 wt.%H_(2) is an attractive high-capacity hydrogen storage material,however,it suffers from high operation temperature and poor reversibility.Herein,a novel and low-cost bifunctional additive,waxberry-like Fe_(3)O_(4) secondary nanospheres assembled from ultrafine primary Fe_(3)O_(4) nanoparticles,is synthesized,which exhibits significant destabilization and bidirectional catalyzation towards(de)hydrogenation of LiBH_(4).With an optimized addition of 30 wt.% waxberry-like Fe_(3)O_(4),the system initiated dehydrogenation below 100℃ and released a total of 8.1 wt.%H_(2) to 400℃.After 10 cycles,a capacity retention of 70% was achieved,greatly superior to previously reported oxides-modified systems.The destabilizing and catalyzing mechanisms of waxberry-like Fe_(3)O_(4) on LiBH_(4) were systematically analyzed by phase and microstructural evolutions during dehydrogenation and hydrogenation cycling as well as density functional theory(DFT)calculations.The present work provides new insights in developing advanced nano-additives with unique structural and multifunctional designs towards LiBH4 hydrogen storage.
