AlTiN,AlTiN–Cu and AlTiN/AlTiN–Cu coatings were prepared on WC–6%Co substrates by cathode arc evaporation deposition technology.Two kinds of nitrogen pressures were used to deposit both AlTiN–Cu and AlTiN/AlTiN–C...AlTiN,AlTiN–Cu and AlTiN/AlTiN–Cu coatings were prepared on WC–6%Co substrates by cathode arc evaporation deposition technology.Two kinds of nitrogen pressures were used to deposit both AlTiN–Cu and AlTiN/AlTiN–Cu coatings.Surface and cross-sectional morphologies of films were observed by scanning electron microscopy(SEM).Crystal structure of films was analyzed by X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).Hardness and adhesion of films were measured by nano-indentation and nano-scratch tester.Cutting tests were performed under milling conditions during wet machining of TC4 alloy.The results show that with addition of Cu,more droplets occur on AlTiN coating surface,but the grain size of it is refined,and the hardness decreases but the toughness is improved.Under higher N2 pressure,the defects on the surface of AlTiN–Cu and AlTiN/AlTiN–Cu coatings diminish,and the hardness of them is enhanced,while the adhesion is reduced.Compared to AlTiN coated cemented carbide tool,the lifetimes of AlTiN–Cu and AlTiN/AlTiN–Cu coated tools under the same N2 pressure are improved by 11%and 24%,respectively.展开更多
Generation of third-order harmonics at 800 nm of femtosecond laser pulses is studied in neutral atmospheric air and in plasma of optical breakdown in air.Its efficiency is measured at different fundamental laser inten...Generation of third-order harmonics at 800 nm of femtosecond laser pulses is studied in neutral atmospheric air and in plasma of optical breakdown in air.Its efficiency is measured at different fundamental laser intensities.A maximum efficiency is observed at the intensity when optical breakdown in atmospheric air starts.The factors that exhibit the main effects on the harmonic generation,including self-focusing in a neutral air and self-focusing in plasma,are discussed.展开更多
Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti:sapphire laser was studied at various pulse durations and energies.The generated supercontinuum was greatly blue-broadened...Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti:sapphire laser was studied at various pulse durations and energies.The generated supercontinuum was greatly blue-broadened due to self-phase modulation in the plasma produced.The measured blue-broadening△ωis proportional to pulse intensity for fixed pulse duration,and values up to 0.7ω(ωbeing the originaI laser frequency)was obtained with a pulse energy of 9.5 mJ and minimum duration of 100 fs.展开更多
We have studied the plasma generation through collecting the charged particles produced in laser-induced break-down in atmospheric air.This breakdovn is produced by ultrashort laser pulses with various durations rangi...We have studied the plasma generation through collecting the charged particles produced in laser-induced break-down in atmospheric air.This breakdovn is produced by ultrashort laser pulses with various durations ranging from 200fs to 2ps at a fixed pulse energy of 8mJ.We found that the plasma yield increases first with the increment of pulse duration and then reaches a plateau at a duration longer than 500fs.The generated plasma temperature is estimated to be higher than 5x 10^(5)K.展开更多
基金Project(2014ZX04012011)supported by Major National Science and Technology Projects,ChinaProject(51327902)supported by the National Natural Science Foundation of China
文摘AlTiN,AlTiN–Cu and AlTiN/AlTiN–Cu coatings were prepared on WC–6%Co substrates by cathode arc evaporation deposition technology.Two kinds of nitrogen pressures were used to deposit both AlTiN–Cu and AlTiN/AlTiN–Cu coatings.Surface and cross-sectional morphologies of films were observed by scanning electron microscopy(SEM).Crystal structure of films was analyzed by X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).Hardness and adhesion of films were measured by nano-indentation and nano-scratch tester.Cutting tests were performed under milling conditions during wet machining of TC4 alloy.The results show that with addition of Cu,more droplets occur on AlTiN coating surface,but the grain size of it is refined,and the hardness decreases but the toughness is improved.Under higher N2 pressure,the defects on the surface of AlTiN–Cu and AlTiN/AlTiN–Cu coatings diminish,and the hardness of them is enhanced,while the adhesion is reduced.Compared to AlTiN coated cemented carbide tool,the lifetimes of AlTiN–Cu and AlTiN/AlTiN–Cu coated tools under the same N2 pressure are improved by 11%and 24%,respectively.
基金Supported by National Key Basic Research Special Foundation under Grant No.G1999075207the National Natural Science Foundation of China under Grant Nos.19884001 and 19525412.
文摘Generation of third-order harmonics at 800 nm of femtosecond laser pulses is studied in neutral atmospheric air and in plasma of optical breakdown in air.Its efficiency is measured at different fundamental laser intensities.A maximum efficiency is observed at the intensity when optical breakdown in atmospheric air starts.The factors that exhibit the main effects on the harmonic generation,including self-focusing in a neutral air and self-focusing in plasma,are discussed.
基金Supported by the National Climbing Project of China,and the National Natural Science Foundation of China under Grant Nos 19884001 and 19525412.
文摘Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti:sapphire laser was studied at various pulse durations and energies.The generated supercontinuum was greatly blue-broadened due to self-phase modulation in the plasma produced.The measured blue-broadening△ωis proportional to pulse intensity for fixed pulse duration,and values up to 0.7ω(ωbeing the originaI laser frequency)was obtained with a pulse energy of 9.5 mJ and minimum duration of 100 fs.
基金the National Climbing Project of China,and the National Natural Science Foundation of China under Grant Nos.19884001 and 19525412.
文摘We have studied the plasma generation through collecting the charged particles produced in laser-induced break-down in atmospheric air.This breakdovn is produced by ultrashort laser pulses with various durations ranging from 200fs to 2ps at a fixed pulse energy of 8mJ.We found that the plasma yield increases first with the increment of pulse duration and then reaches a plateau at a duration longer than 500fs.The generated plasma temperature is estimated to be higher than 5x 10^(5)K.
