摘要 :
Plasma transferred arc (PTA) process are used in remelting of spheroidal graphite cast iron surface. Cementite structure can be obtained on surface layer and shows a significantly high hardness owing to rapid solidification. The c...
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Plasma transferred arc (PTA) process are used in remelting of spheroidal graphite cast iron surface. Cementite structure can be obtained on surface layer and shows a significantly high hardness owing to rapid solidification. The composition of 3.54 wt pct carbon and 2.48 wt pct silicon was fixed as the PTA surface remelting experiment. The specimen with ferrite substrate was selected to study the characteristics of rapid solidification and erosion wear. The results show rapidly solidified microstructure with large amount of eutectic cementite. To increase the remelting current (120A～200A) will increase the eutectic graphite and decrease the volume fraction of eutectic cementite, thus will decrease the hardness. When impact angle is fixed at 30°, the erosion wear resistance increases as increasing the hardness of remelted surface layer. But the erosion wear resistance decreases under the higher impact angle (over 60°).
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摘要 :
A search for exotic dark matter (DM) in the sub-GeV mass range has been conducted using 205 kg day data taken from a p-type point contact germanium detector of the CDEX-10 experiment at China's Jinping underground laboratory. New ...
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A search for exotic dark matter (DM) in the sub-GeV mass range has been conducted using 205 kg day data taken from a p-type point contact germanium detector of the CDEX-10 experiment at China's Jinping underground laboratory. New low-mass dark matter searching channels, neutral current fermionic DM absorption (x + A → v + A) and DM-nucleus 3 → 2 scattering (x + x + A → Φ + A), have been analyzed with an energy threshold of 160 eVee. No significant signal was found; thus new limits on the DM-nucleon interaction cross section are set for both models at the sub-GeV DM mass region. A cross section limit for the fermionic DM absorption is set to be 2.5 × 10~(-46) cm~2 (90% C.L.) at DM mass of 10 MeV/c~2. For the DM-nucleus 3 → 2 scattering scenario, limits are extended to DM mass of 5 and 14 MeV/c~2 for the massless dark photon and bound DM final state, respectively.
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