Monocrystalline Cu exhibits excellent electrical and signal-transmission properties due to its absence of grain boundaries,making it a critical material for the production of micro-machinery and micro-components;howev...Monocrystalline Cu exhibits excellent electrical and signal-transmission properties due to its absence of grain boundaries,making it a critical material for the production of micro-machinery and micro-components;however,achieving ultrahigh precision and ultralow damage machining of functional devices using traditional techniques such as grinding and polishing is extremely challenging.Consequently,nanocutting has emerged as an efficient means to fabricate monocrystalline materials with complex surface characteristics and high surface integrity.Nevertheless,the macroscopic cutting theory of metal materials cannot be applied to nanocutting.Accordingly,in this paper,both simulations and experiments were conducted to examine the chip deformation mechanisms of monocrystalline Cu.First,large-scale molecular dynamics(MD)simulations were conducted to gain a comprehensive understanding of the deformation behavior during nanocutting.This included examining the influencing factors and the variation patterns of the chip deformation coefficient,cutting force,and minimum cutting thickness.Subsequently,nanocutting experiments were performed using a specially designed nanocutting platform with high-resolution online observation by scanning electron microscopy.The experimental results served to verify the accuracy and reliability of theMDmodeling,as they exhibited excellent consistency with the simulated results.Although this work considered monocrystalline Cu,it is believed that the elucidated chip deformation mechanisms could also be applied to other face-centered-cubic metals.These results are of great value for advancing the understanding of the mechanisms of ultraprecision cutting.展开更多
The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions f...The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions for preparing well-dispersed nanoparticles were found as follows: 0.4 mol/L NaBH4 was added into solution containing 0.2 mol/L Cu2+, 1.0% gelatin dispersant in mass fraction, and 1.2 mol/L NH3?H2O at pH 12 and 313 K. In addition, a series of experiments were performed to discover the reaction process. NH3?H2O was found to be able to modulate the reaction process. At pH=10, Cu2+ was transformed to Cu(NH3)42+ as precursor after the addition of NH3?H2O, and then Cu(NH3)42+ was reduced by NaBH4 solution. At pH=12, Cu2+ was transformed to Cu(OH)2 as precursor after the addition of NH3?H2O, and Cu(OH)2 was then reduced by NaBH4 solution.展开更多
基金support of the National Natural Science Foundation of China(Grant No.51805371)the Innovation and Entrepreneurship Training Program of Tianjin University of Commerce(Grant No.202310069067).
文摘Monocrystalline Cu exhibits excellent electrical and signal-transmission properties due to its absence of grain boundaries,making it a critical material for the production of micro-machinery and micro-components;however,achieving ultrahigh precision and ultralow damage machining of functional devices using traditional techniques such as grinding and polishing is extremely challenging.Consequently,nanocutting has emerged as an efficient means to fabricate monocrystalline materials with complex surface characteristics and high surface integrity.Nevertheless,the macroscopic cutting theory of metal materials cannot be applied to nanocutting.Accordingly,in this paper,both simulations and experiments were conducted to examine the chip deformation mechanisms of monocrystalline Cu.First,large-scale molecular dynamics(MD)simulations were conducted to gain a comprehensive understanding of the deformation behavior during nanocutting.This included examining the influencing factors and the variation patterns of the chip deformation coefficient,cutting force,and minimum cutting thickness.Subsequently,nanocutting experiments were performed using a specially designed nanocutting platform with high-resolution online observation by scanning electron microscopy.The experimental results served to verify the accuracy and reliability of theMDmodeling,as they exhibited excellent consistency with the simulated results.Although this work considered monocrystalline Cu,it is believed that the elucidated chip deformation mechanisms could also be applied to other face-centered-cubic metals.These results are of great value for advancing the understanding of the mechanisms of ultraprecision cutting.
文摘The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions for preparing well-dispersed nanoparticles were found as follows: 0.4 mol/L NaBH4 was added into solution containing 0.2 mol/L Cu2+, 1.0% gelatin dispersant in mass fraction, and 1.2 mol/L NH3?H2O at pH 12 and 313 K. In addition, a series of experiments were performed to discover the reaction process. NH3?H2O was found to be able to modulate the reaction process. At pH=10, Cu2+ was transformed to Cu(NH3)42+ as precursor after the addition of NH3?H2O, and then Cu(NH3)42+ was reduced by NaBH4 solution. At pH=12, Cu2+ was transformed to Cu(OH)2 as precursor after the addition of NH3?H2O, and Cu(OH)2 was then reduced by NaBH4 solution.
