Aluminium matrix composite reinforced by Al2O3 particles was produced by adding NH4AlO（OH）HCO3 into molten aluminum.The mechanical properties and wear behavior of the as-fabricated composites were studied.The result...Aluminium matrix composite reinforced by Al2O3 particles was produced by adding NH4AlO（OH）HCO3 into molten aluminum.The mechanical properties and wear behavior of the as-fabricated composites were studied.The results show that during stirring γ-Al2O3 particles were formed via decomposition reaction of NH4AlO（OH）HCO3,and the distribution of Al2O3 particles is more uniform in the matrix aluminum than directly added Al2O3 into molten aluminum.The density and the hardness values of the as-fabricated composites increase with increasing the particle volume fraction,while the tensile strength of the composites decreases with increasing the volume fraction of the Al2O3 particles.The wear rate of the composites decreases with increasing the volume fraction of the particle and loading.The in situ formed Al2O3/Al composite by adding NH4AlO（OH）HCO3 shows more superior mechanical and wear behaviors than that prepared by directly adding Al2O3 particles.展开更多
The new electrorheologicai （ER） material, a particle material composed of Y4O（OH）9（NO3） and NH4NO3, was obtained. They display better ER performance. The shear stress of the suspension of Y4O （OH）9 （NO3） （ ...The new electrorheologicai （ER） material, a particle material composed of Y4O（OH）9（NO3） and NH4NO3, was obtained. They display better ER performance. The shear stress of the suspension of Y4O （OH）9 （NO3） （ NH4NO3 ）2.8 material in dimethyl silicone oil reaches 1469 Pa at an electric field strength （E） of 4.2 kV·mm^-1 and the shear rate （7） of 150 s^-1 The relative shear stress, τ E/τ0（ τE and τ0 are the shear stresses at E = 4.2 and 0 kV·mm^-1 respectively）, is up to 29, which is 19 times that of pure Y2O3 material. The dielectric and conductive property of the materials play important roles in the modification of the ER effect of the particle materials. The researches on these new ER materials are very useful for obtaining a better understanding on the mechanism of the ER effect and finding an ideal ER material.展开更多
在高一化学教材必修（2）第二章第一节＂化学能与热能＂里有一个这样的演示实验：将约20 g Ba（OH）2·8H2O晶体研细后与约10 g NH4Cl晶体一起放入烧杯中,并将烧杯放入滴有几滴水的玻璃片或小木块上,用玻璃棒快速搅拌闻气味,用手触...在高一化学教材必修（2）第二章第一节＂化学能与热能＂里有一个这样的演示实验：将约20 g Ba（OH）2·8H2O晶体研细后与约10 g NH4Cl晶体一起放入烧杯中,并将烧杯放入滴有几滴水的玻璃片或小木块上,用玻璃棒快速搅拌闻气味,用手触摸杯壁下部,试着用手拿起烧杯,观察现象。一、实验存在的问题1.实验成功的关键是小烧杯与下面的玻璃片要粘结在一起,否则会被认为不成功。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
Ir catalyst possesses a good electrocatalytic activity and selectivity for the oxidation of NH3 and/or NH4OH at Ir anode in the potential fixed electrochemical sensor with the neutral solution. Owing to the same elect...Ir catalyst possesses a good electrocatalytic activity and selectivity for the oxidation of NH3 and/or NH4OH at Ir anode in the potential fixed electrochemical sensor with the neutral solution. Owing to the same electrochemical behavior of NH3 and NH4OH in a NaClO4 solution, NH4OH can be used instead of NH3 for the experimental convenience. It was found that the potential of the oxidation peak of NH4OH at the Ir/GC electrode in NaClO4 solutions is at about 0.85 V, and the current density of the oxidation peak of NH4OH is linearly proportional to the concentration of NHaOH. The electrocatalytic oxidation of NH4OH is diffusion-controlled. Especially, Ir has no electrocatalytic activity for the CO oxidation, illustrating that CO does not interfere in the measurement of NH4OH and the potential fixed electrochemical NH3 sensor with the neutral solution, and the anodic Ir catalyst possesses a good selectivity. Therefore, Ir may have practical application in the potential fixed electrochemical NH3 sensor with the neutral solution.展开更多
A simple one-pot approach to synthesizing 5-ethyl-2-methylpyridine（EMP） was established using NHaHCO3 and C2H5OH as starting materials and commercial Cu2O as catalyst and oxidant under hydrothermal con- dition. Diff...A simple one-pot approach to synthesizing 5-ethyl-2-methylpyridine（EMP） was established using NHaHCO3 and C2H5OH as starting materials and commercial Cu2O as catalyst and oxidant under hydrothermal con- dition. Different reaction conditions were researched and the optimal ones were achieved by studying the parameters, that could affect the yield of product and by considering the energy and resource saving. The present study provided an eco-friendlv way to obtaining EMP with lower volatility using fewer toxic starting materials.展开更多
基金Project(2009BAE80B01)supported by the Ministry of Science and Technology,China
文摘Aluminium matrix composite reinforced by Al2O3 particles was produced by adding NH4AlO（OH）HCO3 into molten aluminum.The mechanical properties and wear behavior of the as-fabricated composites were studied.The results show that during stirring γ-Al2O3 particles were formed via decomposition reaction of NH4AlO（OH）HCO3,and the distribution of Al2O3 particles is more uniform in the matrix aluminum than directly added Al2O3 into molten aluminum.The density and the hardness values of the as-fabricated composites increase with increasing the particle volume fraction,while the tensile strength of the composites decreases with increasing the volume fraction of the Al2O3 particles.The wear rate of the composites decreases with increasing the volume fraction of the particle and loading.The in situ formed Al2O3/Al composite by adding NH4AlO（OH）HCO3 shows more superior mechanical and wear behaviors than that prepared by directly adding Al2O3 particles.
文摘The new electrorheologicai （ER） material, a particle material composed of Y4O（OH）9（NO3） and NH4NO3, was obtained. They display better ER performance. The shear stress of the suspension of Y4O （OH）9 （NO3） （ NH4NO3 ）2.8 material in dimethyl silicone oil reaches 1469 Pa at an electric field strength （E） of 4.2 kV·mm^-1 and the shear rate （7） of 150 s^-1 The relative shear stress, τ E/τ0（ τE and τ0 are the shear stresses at E = 4.2 and 0 kV·mm^-1 respectively）, is up to 29, which is 19 times that of pure Y2O3 material. The dielectric and conductive property of the materials play important roles in the modification of the ER effect of the particle materials. The researches on these new ER materials are very useful for obtaining a better understanding on the mechanism of the ER effect and finding an ideal ER material.
文摘在高一化学教材必修（2）第二章第一节＂化学能与热能＂里有一个这样的演示实验：将约20 g Ba（OH）2·8H2O晶体研细后与约10 g NH4Cl晶体一起放入烧杯中,并将烧杯放入滴有几滴水的玻璃片或小木块上,用玻璃棒快速搅拌闻气味,用手触摸杯壁下部,试着用手拿起烧杯,观察现象。一、实验存在的问题1.实验成功的关键是小烧杯与下面的玻璃片要粘结在一起,否则会被认为不成功。
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.
基金Supported by RAE Engineering Center, RAE Systems Inc. Fund, China
文摘Ir catalyst possesses a good electrocatalytic activity and selectivity for the oxidation of NH3 and/or NH4OH at Ir anode in the potential fixed electrochemical sensor with the neutral solution. Owing to the same electrochemical behavior of NH3 and NH4OH in a NaClO4 solution, NH4OH can be used instead of NH3 for the experimental convenience. It was found that the potential of the oxidation peak of NH4OH at the Ir/GC electrode in NaClO4 solutions is at about 0.85 V, and the current density of the oxidation peak of NH4OH is linearly proportional to the concentration of NHaOH. The electrocatalytic oxidation of NH4OH is diffusion-controlled. Especially, Ir has no electrocatalytic activity for the CO oxidation, illustrating that CO does not interfere in the measurement of NH4OH and the potential fixed electrochemical NH3 sensor with the neutral solution, and the anodic Ir catalyst possesses a good selectivity. Therefore, Ir may have practical application in the potential fixed electrochemical NH3 sensor with the neutral solution.
基金Supported by the Natural Science Foundation of Jilin Province, China（No.201215028）, the S＆T Development Program of Jilin Province, China（Nos.20130522128JH, 20140520078JH, 20150204030GX） and the National Natural Science Foundation of China（Nos.21201073, 21401070）.
文摘A simple one-pot approach to synthesizing 5-ethyl-2-methylpyridine（EMP） was established using NHaHCO3 and C2H5OH as starting materials and commercial Cu2O as catalyst and oxidant under hydrothermal con- dition. Different reaction conditions were researched and the optimal ones were achieved by studying the parameters, that could affect the yield of product and by considering the energy and resource saving. The present study provided an eco-friendlv way to obtaining EMP with lower volatility using fewer toxic starting materials.
