A non-sputtering discharge is utilized to verify the effect of replacement of gas ions by metallic ions and consequent decrease in the secondary electron emission coefficient in the discharge current curves in high-po...A non-sputtering discharge is utilized to verify the effect of replacement of gas ions by metallic ions and consequent decrease in the secondary electron emission coefficient in the discharge current curves in high-power impulse magnetron sputtering （HiPIMS）. In the non-sputtering discharge involving hydrogen, replacement of ions is avoided while the rarefaction still contributes. The initial peak and ensuing decay disappear and all the discharge current curves show a similar feature as the HiPIMS discharge of materials with low sputtering yields such as carbon. The results demonstrate the key effect of ion replacement during sputtering.展开更多
An initiation study is presented in which we examine the effect of the normal and the tangential velocity components of a fragment that impacts a covered and a bare Comp-B explosive. The study is based on calibrated n...An initiation study is presented in which we examine the effect of the normal and the tangential velocity components of a fragment that impacts a covered and a bare Comp-B explosive. The study is based on calibrated numerical Lagrangian simulations using the LS-Dyna hydrocode. A special procedure was developed to present the estimated initiation point and the shock wave transition into detonation for various impact angles. The influence of the fragment strength and the steel cover thickness on the detonation threshold were also examined. The velocity threshold results are presented and used to modify the Jacobs-Roslund initiation model.展开更多
The crack initiation mechanism of a Z3CN20.09M duplex stainless steel （DSS） during corrosion fatigue （CF） in water and air at 290 ℃ was investigated by using a CF cracking machine and a scanning electron microsco...The crack initiation mechanism of a Z3CN20.09M duplex stainless steel （DSS） during corrosion fatigue （CF） in water and air at 290 ℃ was investigated by using a CF cracking machine and a scanning electron microscopy （SEM）. The cracks were initiated successively at the persistent stip bands （PSBs）, phase boundaries （PBs） and pitting corrosion points （PCPs） of the specimens when they were tested in water at 290 ℃, while in airat 290 ℃ the cracks were only initiated at the PSBs and PBs. And the cracks were found mainly to initiate at the PSBs and PBs when the specimens were tested in water and air at 290 ℃, respectively. The results also reveal that the cracks were likely to be initiated at the first 20% of fatigue life of the specimens tested in water at 290 ℃. However, the cracks were not found until 50% of fatigue life when tested in air at 290 ℃. Moreover, the crack numbers of the specimens tested in water at 290 ℃ were much more than those tested in air at 290 ℃.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 51301004 and U1330110the Guangdong Innovative and Entrepreneurial Research Team Program under Grant No 2013N080+1 种基金the Shenzhen Science and Technology Research Grant under Grant Nos JCYJ20140903102215536 and JCYJ20150828093127698the City University of Hong Kong Applied Research Grant under Grant No 9667104
文摘A non-sputtering discharge is utilized to verify the effect of replacement of gas ions by metallic ions and consequent decrease in the secondary electron emission coefficient in the discharge current curves in high-power impulse magnetron sputtering （HiPIMS）. In the non-sputtering discharge involving hydrogen, replacement of ions is avoided while the rarefaction still contributes. The initial peak and ensuing decay disappear and all the discharge current curves show a similar feature as the HiPIMS discharge of materials with low sputtering yields such as carbon. The results demonstrate the key effect of ion replacement during sputtering.
文摘An initiation study is presented in which we examine the effect of the normal and the tangential velocity components of a fragment that impacts a covered and a bare Comp-B explosive. The study is based on calibrated numerical Lagrangian simulations using the LS-Dyna hydrocode. A special procedure was developed to present the estimated initiation point and the shock wave transition into detonation for various impact angles. The influence of the fragment strength and the steel cover thickness on the detonation threshold were also examined. The velocity threshold results are presented and used to modify the Jacobs-Roslund initiation model.
基金financial support from the"863"Program of China under Nos.2008AA031702 and 2012AA03A507
文摘The crack initiation mechanism of a Z3CN20.09M duplex stainless steel （DSS） during corrosion fatigue （CF） in water and air at 290 ℃ was investigated by using a CF cracking machine and a scanning electron microscopy （SEM）. The cracks were initiated successively at the persistent stip bands （PSBs）, phase boundaries （PBs） and pitting corrosion points （PCPs） of the specimens when they were tested in water at 290 ℃, while in airat 290 ℃ the cracks were only initiated at the PSBs and PBs. And the cracks were found mainly to initiate at the PSBs and PBs when the specimens were tested in water and air at 290 ℃, respectively. The results also reveal that the cracks were likely to be initiated at the first 20% of fatigue life of the specimens tested in water at 290 ℃. However, the cracks were not found until 50% of fatigue life when tested in air at 290 ℃. Moreover, the crack numbers of the specimens tested in water at 290 ℃ were much more than those tested in air at 290 ℃.
