The ilmenite welding electrode has advantages of low cost and excellent welding technological properties.However, the welding quality is affected adversely by its poor crack resistance.To solve this problem, 12 kinds ...The ilmenite welding electrode has advantages of low cost and excellent welding technological properties.However, the welding quality is affected adversely by its poor crack resistance.To solve this problem, 12 kinds of rare earths coating formulas were optimized by means of orthogonal test design and curve fitting.Then the powders containing La/Ce O2 were extruded into ilmenite welding electrode through screw-type pressing–scribbling machine.After that, a series of mechanical properties tests were conducted according to national standards.Next, the mechanical properties data were analyzed comprehensively by analyzing variance, boxplot as well as Minitab 3D surface chart.The results show that compared with the formula without rare earth, the deposited metal’s impact toughness,the lower yield strength, the tensile strength, and the hardness are increased by 54.44 %, 9.25 %, 6.37 %, and4.27 %, respectively.In other words, Electrode 6 with the La/Ce O2 amount of 0.5 %/0.1 % in coating has better mechanical properties.展开更多
Ammonia （NH3） has an important use in the chemical industry and is widely found in industrial wastewater. For this investigation of copper-based rare earth composite metal materials, aqueous solutions containing 400...Ammonia （NH3） has an important use in the chemical industry and is widely found in industrial wastewater. For this investigation of copper-based rare earth composite metal materials, aqueous solutions containing 400 mg/L of ammonia were oxidized in a batch-bed reac-tor with a catalyst prepared by the co-precipitation of copper nitrate, lanthanum nitrate and cerium nitrate. Barely any of the dissolved ammo-nia was removed by wet oxidation without a catalyst, but about 88% of the ammonia was reduced during wet oxidation over the catalysts at 423 K with an oxygen partial pressure of 4.0 MPa. The catalytic redox behavior was determined by cyclic voltammetry （CV）. Furthermore, the catalysts were characterized using thermogravimetric analyzer （TGA） and scanning electron microscope-energy dispersive X-ray spectroscopy （SEM-EDX）, which showed that the catalytic behavior was related to the metal oxide properties of the catalyst. In addition, the copper-lanthanum-cerium composite-induced cytotoxicity in the human lung MRC-5 cell line was tested, and the percentage cell survival was determined by 3-（4,5-dimethylthiazol-2-yl）-5-（3-carboxymethoxyphenyl）-2-（4-sulfophenyl）-2H-tetra-zolium （MTS） analysis in vitro. No ap-parent cytotoxicity was observed when the human lung cells were exposed to the copper-lanthanum-cerium composite.展开更多
Oleic acid coated LaF3:Ce nanoparticles were synthesized and embedded in polyacrylamide through a two-step procedure. In the first step nanoparticles were synthesized by adopting co-precipitation technique and in the ...Oleic acid coated LaF3:Ce nanoparticles were synthesized and embedded in polyacrylamide through a two-step procedure. In the first step nanoparticles were synthesized by adopting co-precipitation technique and in the second step, nanoparticles were embedded in polyacrylamide (PAM) hydro-gel through the solution route. Nanoparticels were characterized for their crystal structure, particle size, organic coating and photoluminescence behavior using X-ray diffracttion, SEM, TEM, FTIR and photoluminescence spectroscopy. Size of nanoparticles was estimated using the Scherer formula. Polymer nano composite (PNC) material was synthesized with two different weight percent of the nano powder viz 1.634% (termed as NG1) and 0.1664% (termed as NG2). The nanoparticle-polymer composite exhibits emissions at 308 and 370 nm. A comparison of the emission spectrum of LaF3:Ce nano-powder pellet with that of the composite suggests a suppression of emission from the PAM host in the composite.展开更多
To have an insight into the occurrence of inverse Hall-Petch relationship in ultrafine-grained(UFG) aluminum alloys produced by severe plastic deformation(SPD),ultra-SPD(i.e.inducing several ten thousand shear strains...To have an insight into the occurrence of inverse Hall-Petch relationship in ultrafine-grained(UFG) aluminum alloys produced by severe plastic deformation(SPD),ultra-SPD(i.e.inducing several ten thousand shear strains via high-pressure torsion,HPT) followed by aging is applied to an Al-La-Ce alloy.Average nanograin sizes of 40 and 80 nm are successfully achieved together with strain-induced Lomer-Cottrell dislocation lock formation and aging-induced semi-coherent Al_(11)(La,Ce)_3 precipitation.Analysis of hardening mechanisms in this alloy compared to SPD-processed pure aluminum with micrometer grain sizes,SPD-processed Al-based alloys with submicrometer grain sizes and ultra-SPD-processed Al-Ca alloy with nanograin sizes reveals the presence of two breaks in the Hall-Petch relationship.First,a positive upbreak appears when the grain sizes decrease from micrometer to submicrometer which is due to extra hardening by solute-dislocation interactions.Second,a negative down-break and softening occur by decreasing the grain sizes from submicrometer to nanometer which is caused by weakening the dislocation hardening mechanism with minor contribution of the inverse Hall-Petch mechanism.Detailed analyses confirm that nanograin formation is not necessarily a solution for extra hardening of Al-based alloys and other accompanying strategies such as grain-boundary segregation and precipitation are required to overcome such a down-break and softening.展开更多
基金financially supported by the National Natural Science Foundation of China (No.51305178)Xuzhou City Science and Technology Plan Project (No.XC12A013)
文摘The ilmenite welding electrode has advantages of low cost and excellent welding technological properties.However, the welding quality is affected adversely by its poor crack resistance.To solve this problem, 12 kinds of rare earths coating formulas were optimized by means of orthogonal test design and curve fitting.Then the powders containing La/Ce O2 were extruded into ilmenite welding electrode through screw-type pressing–scribbling machine.After that, a series of mechanical properties tests were conducted according to national standards.Next, the mechanical properties data were analyzed comprehensively by analyzing variance, boxplot as well as Minitab 3D surface chart.The results show that compared with the formula without rare earth, the deposited metal’s impact toughness,the lower yield strength, the tensile strength, and the hardness are increased by 54.44 %, 9.25 %, 6.37 %, and4.27 %, respectively.In other words, Electrode 6 with the La/Ce O2 amount of 0.5 %/0.1 % in coating has better mechanical properties.
基金National Natural Science Foundation of China(21276036)Liaoning Provincial Nature Science Foundation of China(2014025018)the Fundamental Research Funds for the Central Universities(3132014323)
基金supported by the National Science Council of Taiwan (NSC 98-2221-E-132-003-MY3)
文摘Ammonia （NH3） has an important use in the chemical industry and is widely found in industrial wastewater. For this investigation of copper-based rare earth composite metal materials, aqueous solutions containing 400 mg/L of ammonia were oxidized in a batch-bed reac-tor with a catalyst prepared by the co-precipitation of copper nitrate, lanthanum nitrate and cerium nitrate. Barely any of the dissolved ammo-nia was removed by wet oxidation without a catalyst, but about 88% of the ammonia was reduced during wet oxidation over the catalysts at 423 K with an oxygen partial pressure of 4.0 MPa. The catalytic redox behavior was determined by cyclic voltammetry （CV）. Furthermore, the catalysts were characterized using thermogravimetric analyzer （TGA） and scanning electron microscope-energy dispersive X-ray spectroscopy （SEM-EDX）, which showed that the catalytic behavior was related to the metal oxide properties of the catalyst. In addition, the copper-lanthanum-cerium composite-induced cytotoxicity in the human lung MRC-5 cell line was tested, and the percentage cell survival was determined by 3-（4,5-dimethylthiazol-2-yl）-5-（3-carboxymethoxyphenyl）-2-（4-sulfophenyl）-2H-tetra-zolium （MTS） analysis in vitro. No ap-parent cytotoxicity was observed when the human lung cells were exposed to the copper-lanthanum-cerium composite.
文摘Oleic acid coated LaF3:Ce nanoparticles were synthesized and embedded in polyacrylamide through a two-step procedure. In the first step nanoparticles were synthesized by adopting co-precipitation technique and in the second step, nanoparticles were embedded in polyacrylamide (PAM) hydro-gel through the solution route. Nanoparticels were characterized for their crystal structure, particle size, organic coating and photoluminescence behavior using X-ray diffracttion, SEM, TEM, FTIR and photoluminescence spectroscopy. Size of nanoparticles was estimated using the Scherer formula. Polymer nano composite (PNC) material was synthesized with two different weight percent of the nano powder viz 1.634% (termed as NG1) and 0.1664% (termed as NG2). The nanoparticle-polymer composite exhibits emissions at 308 and 370 nm. A comparison of the emission spectrum of LaF3:Ce nano-powder pellet with that of the composite suggests a suppression of emission from the PAM host in the composite.
基金financially supported by the Light Metals Educational Foundation of Japan,the Ministry of Education,Culture,Sports,Science and Technology (MEXT) of Japan (No. 19H05176,21H00150)the Russian Science Foundation (No. 17-19-01311)。
文摘To have an insight into the occurrence of inverse Hall-Petch relationship in ultrafine-grained(UFG) aluminum alloys produced by severe plastic deformation(SPD),ultra-SPD(i.e.inducing several ten thousand shear strains via high-pressure torsion,HPT) followed by aging is applied to an Al-La-Ce alloy.Average nanograin sizes of 40 and 80 nm are successfully achieved together with strain-induced Lomer-Cottrell dislocation lock formation and aging-induced semi-coherent Al_(11)(La,Ce)_3 precipitation.Analysis of hardening mechanisms in this alloy compared to SPD-processed pure aluminum with micrometer grain sizes,SPD-processed Al-based alloys with submicrometer grain sizes and ultra-SPD-processed Al-Ca alloy with nanograin sizes reveals the presence of two breaks in the Hall-Petch relationship.First,a positive upbreak appears when the grain sizes decrease from micrometer to submicrometer which is due to extra hardening by solute-dislocation interactions.Second,a negative down-break and softening occur by decreasing the grain sizes from submicrometer to nanometer which is caused by weakening the dislocation hardening mechanism with minor contribution of the inverse Hall-Petch mechanism.Detailed analyses confirm that nanograin formation is not necessarily a solution for extra hardening of Al-based alloys and other accompanying strategies such as grain-boundary segregation and precipitation are required to overcome such a down-break and softening.
