The aim of this investigation is to reveal the influence of rare earths(RE) addition on mechanical properties of plasma nitrocarburized 17-4PH steel.The nitrocarburized layers were characterized by optical microscope,...The aim of this investigation is to reveal the influence of rare earths(RE) addition on mechanical properties of plasma nitrocarburized 17-4PH steel.The nitrocarburized layers were characterized by optical microscope,scanning electron microscope equipped with energy dispersive X-ray analyzer,X-ray diffractometer,microhardness tester and pin-on-disc tribometer.The results showed that RE atoms could diffuse into the surface layer of 17-4PH steel plasma nitrocarburized at 500 °C for 4 h and did not change the phase structure of the surface layer.The presence of RE in the surface layer increased thickness,toughness,microhardness and wear resistance of the nitrocarburized layer.Additionally,grain boundary and micro-crack parallel to the surface have been depressed by plasma nitrocarburizing with RE addition.The severe plastic deformation,adhesion and abrasive wear produced during wear of the experimental steel could be changed into mild micro-abrasion and slight micro-crack wear by plasma nitrocarburizing without and with RE addition,respectively.展开更多
Cu-30Ni-xRE(x=0-0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were inves...Cu-30Ni-xRE(x=0-0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were investigated using optical microscope,scanning electronic microscope with energy-dispersive spectrometer and electrochemical measurement system.The results showed that the corrosion resistance of Cu-30Ni alloy was greatly improved by adding proper amount of RE,whereas excess addition of RE worsened the corrosion resistance.The optimum RE content was about 0.095 wt.%.In comparison with the alloy without RE,the corrosion potential and corrosion current density of Cu-30Ni alloy containing proper RE decreased by about -40 mV and 0.47 μA/cm2,respectively.The roles of RE purifying the impurities and decreasing Ni element segregation,which resulted in the decrease of galvanic cell and corrosion potential gradient in Cu-30Ni alloy,were responsible for the improvement of corrosion resistance.展开更多
Monometallic catalyst Pt/SAPO-11 was prepared by impregnation method.Bimetallic catalysts LaPt/SAPO-11 or CePt/SAPO-11 was prepared by sequential impregnation method.The catalysts were characterized by X-ray diffracti...Monometallic catalyst Pt/SAPO-11 was prepared by impregnation method.Bimetallic catalysts LaPt/SAPO-11 or CePt/SAPO-11 was prepared by sequential impregnation method.The catalysts were characterized by X-ray diffraction(XRD),nitrogen adsorption,temperature-programmed desorption of ammonia(NH3-TPD),and Fourier transform infrared spectroscopy(FT-IR) techniques.The results showed that with the addition of rare earths the BET surface areas,pore volume,the amount of Bronsted acid and the total acidity of catalysts decreased slightly.However,the additive addition could lead to an increase in the amount of Lewis acid.Meanwhile,the introduction of additive was feasible to promote the dispersity of Pt.In addition,the hydroisomerization of n-heptane over different catalysts was studied.Compared with Pt/SAPO-11,LaPt/SAPO-11 or CePt/SAPO-11 showed higher catalytic activity and yield of i-C7 due to its higher Pt dispersion.展开更多
The effect of adding rare earths and its oxides into Fe based high chromium alloy powder system during mechanical milling on the powder was studied. The results show that the amount of removed active oxygen achieves t...The effect of adding rare earths and its oxides into Fe based high chromium alloy powder system during mechanical milling on the powder was studied. The results show that the amount of removed active oxygen achieves the maximum value when the addition of element cerium amounts to 0 4%～0 6%. Part of the rare earth oxides added are favorable to the deoxidization. Thermodynamic analysis indicates that rare earths can deoxidize the majority amount of oxygen and preserve carbon in the powder system.展开更多
4. Increasing import of rare earth resources products As a big producer and an important export country of rare earth products for years, rare earths import is in an auxiliary position in China. Import volume is rathe...4. Increasing import of rare earth resources products As a big producer and an important export country of rare earth products for years, rare earths import is in an auxiliary position in China. Import volume is rather small. However, since the strengthened macro control measures展开更多
The company covers separation with whole lines of light, medium and heavy rare earths, with annual separation volume of rare earth oxides of 4,500 tons. It also produces rare earth oxides, fluorides and salts. Product...The company covers separation with whole lines of light, medium and heavy rare earths, with annual separation volume of rare earth oxides of 4,500 tons. It also produces rare earth oxides, fluorides and salts. Products with high-purity and super-high-purity are produced according to customer's request. Under the technological guidance of domestic experts and application of modern展开更多
基金supported by the National Natural Science Foundation of China (50871035)the Ph.D. Programs Foundation of Ministry of Education of China (20060213017)
文摘The aim of this investigation is to reveal the influence of rare earths(RE) addition on mechanical properties of plasma nitrocarburized 17-4PH steel.The nitrocarburized layers were characterized by optical microscope,scanning electron microscope equipped with energy dispersive X-ray analyzer,X-ray diffractometer,microhardness tester and pin-on-disc tribometer.The results showed that RE atoms could diffuse into the surface layer of 17-4PH steel plasma nitrocarburized at 500 °C for 4 h and did not change the phase structure of the surface layer.The presence of RE in the surface layer increased thickness,toughness,microhardness and wear resistance of the nitrocarburized layer.Additionally,grain boundary and micro-crack parallel to the surface have been depressed by plasma nitrocarburizing with RE addition.The severe plastic deformation,adhesion and abrasive wear produced during wear of the experimental steel could be changed into mild micro-abrasion and slight micro-crack wear by plasma nitrocarburizing without and with RE addition,respectively.
基金Project Financially supported by Major State Basic Research Development Program of China (2007CB616903)
文摘Cu-30Ni-xRE(x=0-0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were investigated using optical microscope,scanning electronic microscope with energy-dispersive spectrometer and electrochemical measurement system.The results showed that the corrosion resistance of Cu-30Ni alloy was greatly improved by adding proper amount of RE,whereas excess addition of RE worsened the corrosion resistance.The optimum RE content was about 0.095 wt.%.In comparison with the alloy without RE,the corrosion potential and corrosion current density of Cu-30Ni alloy containing proper RE decreased by about -40 mV and 0.47 μA/cm2,respectively.The roles of RE purifying the impurities and decreasing Ni element segregation,which resulted in the decrease of galvanic cell and corrosion potential gradient in Cu-30Ni alloy,were responsible for the improvement of corrosion resistance.
基金supported by the Foundation of Jiangsu Key Laboratory of Precious Metals Chemistry (SYGK0710)Natural Scientific Foundation of Jiangsu Teachers University of Technology (KYY06029)
文摘Monometallic catalyst Pt/SAPO-11 was prepared by impregnation method.Bimetallic catalysts LaPt/SAPO-11 or CePt/SAPO-11 was prepared by sequential impregnation method.The catalysts were characterized by X-ray diffraction(XRD),nitrogen adsorption,temperature-programmed desorption of ammonia(NH3-TPD),and Fourier transform infrared spectroscopy(FT-IR) techniques.The results showed that with the addition of rare earths the BET surface areas,pore volume,the amount of Bronsted acid and the total acidity of catalysts decreased slightly.However,the additive addition could lead to an increase in the amount of Lewis acid.Meanwhile,the introduction of additive was feasible to promote the dispersity of Pt.In addition,the hydroisomerization of n-heptane over different catalysts was studied.Compared with Pt/SAPO-11,LaPt/SAPO-11 or CePt/SAPO-11 showed higher catalytic activity and yield of i-C7 due to its higher Pt dispersion.
文摘The effect of adding rare earths and its oxides into Fe based high chromium alloy powder system during mechanical milling on the powder was studied. The results show that the amount of removed active oxygen achieves the maximum value when the addition of element cerium amounts to 0 4%～0 6%. Part of the rare earth oxides added are favorable to the deoxidization. Thermodynamic analysis indicates that rare earths can deoxidize the majority amount of oxygen and preserve carbon in the powder system.
文摘4. Increasing import of rare earth resources products As a big producer and an important export country of rare earth products for years, rare earths import is in an auxiliary position in China. Import volume is rather small. However, since the strengthened macro control measures
文摘The company covers separation with whole lines of light, medium and heavy rare earths, with annual separation volume of rare earth oxides of 4,500 tons. It also produces rare earth oxides, fluorides and salts. Products with high-purity and super-high-purity are produced according to customer's request. Under the technological guidance of domestic experts and application of modern
