Superalloys are grouped as hard-to-cut materials with relatively poor machinability.Tool wear is considered one of the main machinability attributes in machining superalloys.Although numerous works have been reported ...Superalloys are grouped as hard-to-cut materials with relatively poor machinability.Tool wear is considered one of the main machinability attributes in machining superalloys.Although numerous works have been reported on factors governing tool life in machining superalloys,no study was found on the effect of nanoparticles stability on nanofluid performance and consequently resulted tool wear morphologies.In the present work,the nanoparticles were reinforced by means of improving the stability of the base fluid.To that accomplished,the surface active agent (surfactant) was added to the base cutting fluid as a reinforcing element.The effects of new lubricant on the tool wear morphology of A286 works parts were assessed.展开更多
A silver nanoparticle(Ag NP) with good monodispersity was produced by a convenient method for reducing of Ag NO3 with N, N-dimethylacetamide in the presence of polyvinyl pyrrolidone(PVP) as the surface modification ag...A silver nanoparticle(Ag NP) with good monodispersity was produced by a convenient method for reducing of Ag NO3 with N, N-dimethylacetamide in the presence of polyvinyl pyrrolidone(PVP) as the surface modification agent. The shape and size of the Ag NP with reaction time were taken as variables. The surface plasmon band transition was monitored with reaction mixture time at different temperatures. The Ag NP crystallinity increases with the reaction time, and the reduction efficiency is very low when Ag NP solution is dealt at room temperature even after two days, while it is greatly improved at 160 °C only for 25 min. Ag NP modified by the as-synthesized PVP has a face-centered cubic crystalline structure, in which Ag NP could develop into a spherical morphology with a very narrow size distribution of 2-11 nm. The preparation provides a new reducing agent to form Ag NP with simpler operation and shorter time.展开更多
A non-destructive, safe and practical strategy to produce high quality graphene in high yield is urgently required, since this would pave the way for a wide range of applications of graphene in the future. Here we pre...A non-destructive, safe and practical strategy to produce high quality graphene in high yield is urgently required, since this would pave the way for a wide range of applications of graphene in the future. Here we present a pH-responsive water-dispersible method for the exfoliation and functionalization of graphene by using lysozyme. The pH-responsive dispersion of graphene may be useful for the reversible assembly of multicomponent/multifunctional nanohybrid materials and nanoscale electronic devices. More importantly, composites can be easily constructed through the interactions between disulphide groups in lysozyme and gold nanoparticles （AuNPs）. The resulting graphene-AuNPs composites show excellent catalytic activity towards reduction of o-nitroaniline by NaBH4. Since lysozyme is low cost and has antibacterial properties, and has been widely used in food preservation, medicine and the pharmaceutical industry, our approach may open a new scalable route for the manufacture of high-quality, nondestructive graphene for practical applications.展开更多
文摘Superalloys are grouped as hard-to-cut materials with relatively poor machinability.Tool wear is considered one of the main machinability attributes in machining superalloys.Although numerous works have been reported on factors governing tool life in machining superalloys,no study was found on the effect of nanoparticles stability on nanofluid performance and consequently resulted tool wear morphologies.In the present work,the nanoparticles were reinforced by means of improving the stability of the base fluid.To that accomplished,the surface active agent (surfactant) was added to the base cutting fluid as a reinforcing element.The effects of new lubricant on the tool wear morphology of A286 works parts were assessed.
基金Project(126223)supported by Postdoctoral Fund of Central South University,ChinaProject(13JJ4102)supported by the Natural Science Foundation of Hunan Province,ChinaProject(14A025)supported by the Research Foundation of Education Bureau of Hunan Province,China
文摘A silver nanoparticle(Ag NP) with good monodispersity was produced by a convenient method for reducing of Ag NO3 with N, N-dimethylacetamide in the presence of polyvinyl pyrrolidone(PVP) as the surface modification agent. The shape and size of the Ag NP with reaction time were taken as variables. The surface plasmon band transition was monitored with reaction mixture time at different temperatures. The Ag NP crystallinity increases with the reaction time, and the reduction efficiency is very low when Ag NP solution is dealt at room temperature even after two days, while it is greatly improved at 160 °C only for 25 min. Ag NP modified by the as-synthesized PVP has a face-centered cubic crystalline structure, in which Ag NP could develop into a spherical morphology with a very narrow size distribution of 2-11 nm. The preparation provides a new reducing agent to form Ag NP with simpler operation and shorter time.
基金Acknowledgements Financial support was provided by the National Basic Research Program （973 Program） of China （Nos. 2011CB936004 and 2012CB720602）, and theNational Natural Science Foundation of China （NSFC）, Nos. （21210002 and 91213302）.
文摘A non-destructive, safe and practical strategy to produce high quality graphene in high yield is urgently required, since this would pave the way for a wide range of applications of graphene in the future. Here we present a pH-responsive water-dispersible method for the exfoliation and functionalization of graphene by using lysozyme. The pH-responsive dispersion of graphene may be useful for the reversible assembly of multicomponent/multifunctional nanohybrid materials and nanoscale electronic devices. More importantly, composites can be easily constructed through the interactions between disulphide groups in lysozyme and gold nanoparticles （AuNPs）. The resulting graphene-AuNPs composites show excellent catalytic activity towards reduction of o-nitroaniline by NaBH4. Since lysozyme is low cost and has antibacterial properties, and has been widely used in food preservation, medicine and the pharmaceutical industry, our approach may open a new scalable route for the manufacture of high-quality, nondestructive graphene for practical applications.
