Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment(UPT).Surface enhancement layer leads to the complete change of crack initiation sites.However,crack initiation ...Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment(UPT).Surface enhancement layer leads to the complete change of crack initiation sites.However,crack initiation mechanism keeps the same and results in a single-faceted morphology at crack initiation site.Microcracks initiate as Mode Ⅱ crack within the original grain,but deflect to Mode I crack outside of the original cracked grain.A threshold SIF value is proposed to evaluate the retarding effect of grain boundary on microcrack propagation.Outside of the original cracked grain,Mode I crack propagation below the threshold ΔK_(σ-th) is responsible for the formation of fine granular area(FGA,a nano-grain layer).Based on the Numerous Cyclic Pressing(NCP) model,it is proposed that crack type should be another necessary condition for the formation of FGA.展开更多
The composite photoanodes composed by cobalt phosphate catalyst(Co-Pi) modified semiconductor have been widely used for solar water splitting,but the improvement mechanism has not been experimentally confirmed.Here we...The composite photoanodes composed by cobalt phosphate catalyst(Co-Pi) modified semiconductor have been widely used for solar water splitting,but the improvement mechanism has not been experimentally confirmed.Here we use transient photoelectrochemical measurements and impedance spectroscopy to investigate the effect of Co-Pi catalyst on hematite nanowire photoanode.It is found that under illumination the Co-Pi catalyst can efficiently promote the transfer of photo-generated holes to the Co-Pi layer by increasing the electrical conductivity of the composite structure under a low potential.The Co-Pi catalyst can recombine with photo-generated electrons to reduce the surface recombination efficiency of photo-generated holes and electrons under a high potential.These results provide important new understanding of the performance improvement mechanism for the Co-Pi-modified semiconductor nanowire composite photoanodes.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 12102280, 12172238, 11832007, 12022208, 12072212, and 52003181)the Science & Technology Support Program of Sichuan Province (Nos. 2020YJ0230, and 2021YJ0555)the Fundamental Research Funds for the Central Universities of China (No.2021SCU12129)
文摘Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment(UPT).Surface enhancement layer leads to the complete change of crack initiation sites.However,crack initiation mechanism keeps the same and results in a single-faceted morphology at crack initiation site.Microcracks initiate as Mode Ⅱ crack within the original grain,but deflect to Mode I crack outside of the original cracked grain.A threshold SIF value is proposed to evaluate the retarding effect of grain boundary on microcrack propagation.Outside of the original cracked grain,Mode I crack propagation below the threshold ΔK_(σ-th) is responsible for the formation of fine granular area(FGA,a nano-grain layer).Based on the Numerous Cyclic Pressing(NCP) model,it is proposed that crack type should be another necessary condition for the formation of FGA.
基金financially supported by the National Natural Science Foundation of China (No.21503109)the Research-Starting Funds for Introduced Talents of Nanjing Tech University。
文摘The composite photoanodes composed by cobalt phosphate catalyst(Co-Pi) modified semiconductor have been widely used for solar water splitting,but the improvement mechanism has not been experimentally confirmed.Here we use transient photoelectrochemical measurements and impedance spectroscopy to investigate the effect of Co-Pi catalyst on hematite nanowire photoanode.It is found that under illumination the Co-Pi catalyst can efficiently promote the transfer of photo-generated holes to the Co-Pi layer by increasing the electrical conductivity of the composite structure under a low potential.The Co-Pi catalyst can recombine with photo-generated electrons to reduce the surface recombination efficiency of photo-generated holes and electrons under a high potential.These results provide important new understanding of the performance improvement mechanism for the Co-Pi-modified semiconductor nanowire composite photoanodes.