Effect of metallic content on mechanical property of Ni/（10NiO-NiFe2O4 ） cermets

1 INTRODUCTIONThe use of inert or non-consumable anodes forreplacement of consumable carbon anodes in Hall-H啨roult electrolysis cells for the production of alu-minum has been a technical and commercial goalfor many decades .In the present process ,consumable carbon an-odes are used,andthe anode product is CO2. Withaninert anode ,the cell reaction will be :Al2O3=2Al +23O2(1)The basic requirements for aninert anode are :1) to exhibit a lowcorrosion rate in the high tem-perature melts an…     

Influence of KOH activation techniques on pore structure and electrochemical property of carbon electrode materials

1 INTRODUCTIONSupercapacitor is a kind of newenergy storagedevice , which can fill the gap between the conven-tional capacitor and the battery[1 ,2]. Supercapa-ciors are nowutilizedin many fields ,such as spaceindustry ,national defense ,warindustry ,electricalvehicle , wireless communication, and consume e-lectronics .It is well known that the electrode ma-terial is the key factor to determine the perform-ance of supercapacitor . At present ,the activatedcarbonis the main marketed availa…     

Preparation of uitrafine α-Al2O3 powders by catalytic sintering of ammonium aluminum carbonate hydroxide at low temperature

The precursor of ammonium aluminum carbonate hydroxide was synthesized by using aluminum sulfate （Al2 （SO4）3 ） and ammonium carbonate（（NH4 ）2CO3 ）. The effects of α-Al2 O3 seeds and mixture composed of α- Al2O3 and ammonium nitrate, as well as multiplex catalysts （AT） on phase transformation of alumina in sintering process were investigated respectively. The results show that the α-Al2 O3 seeds and the mixture of α-Al2 O3 and ammonium nitrate can lower the phase transformation temperature of α-Al2O3 to different extents while the particles obtained agglomerate heavily. AT has great potential synergistic effects on the phase transformation of alumina and reduces the phase transformation temperature of α-Al2O3 and the trends of necking-formation between particles. Therefore the dispersion of powder particles is improved significantly.     

Effect of sintering atmosphere on composition and properties of NiFe2O4 ceramic

Ni Fe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound Ni Fe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10-5, 2×10-4 and 2×10-3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of Ni Fe2O4 and Ni O. With increasing oxygen content, Ni Fe2O4 content in the ceramic increases, while Ni O content appears a contrary trend. In vacuum, Ni Fe2O4 ceramic has average grain size of 3.94 μm, and bending strength of85.12 MPa. The changes of the phase composition and mechanical properties of Ni Fe2O4 based cermets are mainly caused by the alteration of their properties of Ni Fe2O4 ceramic.     

Densification and sintering dynamics of 10NiO-NiFe2O4 composites doped with CaO

The effects of CaO content in the range from 0 to 4.0%, and sintering temperature on the phase composition, relative density and electrical conductivity of 10NiO-NiFe2O4 composites doped with CaO were studied. The results show that there is no change of structure for NiO or NiFe2O4; there is apparent oxygen absorbing and releasing behavior during the heating process in air for 10NiO-NiFe2O4 composites. Introduction of CaO can accelerate the densification of 10NiO-NiFe2O4 composites. The maximum value of relative density is 98.75% for composite doped with 2.0% CaO and sintered at 1 200 ℃, which is beyond about 20% for the undoped composites. The sintering activated energy of sample containing 2% CaO decreases by 15.87 kJ/mol, compared with that of the undoped sample.     

Electrochemical behavior of wound supercapacitors with propylene carbonate and acetonitrile based nonaqueous electrolytes

The activated carbon wound supercapacitors with TEABF₄/propylene carbonate (PC) and TEABF₄/acetonitrile (AN) electrolytes were prepared. The effects of the electrolyte and temperature on the capacitance behavior were investigated by cyclic voltammetry (CV) and constant current charge-discharge. Compared with the PC-based supercapacitor, the AN-based supercapacitor has higher capacitance and lower equivalent serial resistance (R _ES) at discharge currents ranging from 5 to 1 000 mA and 25 °C. Moreover, temperature effects are more prominent for PC-based supercapacitor than for AN-based supercapacitor. When the measurement temperature ranges from 60 °C to −40 °C the capacitance changes from 5.1 to 2.5 F and R _ES changes from 135 to 876 mΩ for the PC-based supercapacior, while the AN-based supercapacitor shows less change in capacitance and R _ES. Thus AN-based supercapacitor exhibits excellent power characteristics and temperature property. Foundation item: Project(20803095) supported by the National Natural Science Foundation of China; Project(2008AA03Z207) supported by the National High Technology Research and Development Program of China     

Digital characterization and mathematic model of sodium penetration into cathode material for aluminum electrolysis

The sodium expansion curves of semi-graphitic cathode and TiB₂/C composite cathode with different TiB₂ contents were measured with the improved Rapoport-Samoilenko apparatus. The mathematic model of the sodium expansion was deduced on the basis of the experimental results. The sodium expansion parameter (a) and penetration rate factor (Q), were introduced into the model. The model was validated with the experimental sodium expansion curves self-measured and reported. The results show that the variation tendency of the sodium expansion parameter (a) and penetration rate factor (Q) is consistent with that of the experimental curves. The model is capable of not only conveniently judging the cathode quality, but also favorably establishing a unified standard of the resistance to sodium penetration of cathode. Foundation item: Project(2005CB623703) supported by the Major State Basic Research and Development Program of China; Project(2008AA030502) supported by the National High-Tech Research and Development Program of China; Project(GUIKEJI0639032) supported by the Science Fund Project of Guangxi Province, China     

HLA-DDS分布式通信卫星仿真系统

通信卫星仿真系统用于模拟通信卫星工作状态,在验证整星方案、测控对接试验、飞行控制演练、卫星操作培训、故障排查等活动中都具有非常重要的作用。随着仿真技术的发展和应用,卫星各分系统研制了相应的专业仿真系统。但是如何有效地整合各专业仿真系统,形成一个整星级仿真系统,一直是一个亟待解决的难题。本文通过研究分布式仿真系统,设计了HLA-DDS混合的分布式通信卫星仿真系统架构,可以有效整合各专业仿真系统,形成一个整星级高精度仿真系统。     

CaO对17Ni/(10NiO-NiFe2O4)金属陶瓷的致密化及力学性能的影响

采用冷压-烧结技术制备了CaO掺杂的17Ni/(10NiO-NiFe₂O₄)金属陶瓷惰性阳极。研究了CaO的添加量和烧结温度对17Ni/(10NiO-NiFe₂O₄)金属陶瓷的物相组成、 致密度和力学性能的影响。结果表明, CaO含量在小于5.0wt%范围内, 烧结样品由Ni、 NiO和NiFe₂O₄组成。CaO掺杂对17Ni/(10NiO-NiFe₂O₄)金属陶瓷具有明显的助烧作用。当烧结温度为1250℃时, CaO掺杂量为1.0wt%的样品致密度达到最大值97.87%, 继续增加CaO掺杂量将导致材料致密度的下降。当烧结温度从1250℃提高到1350℃时, 当CaO掺杂量小于0.5wt%时, 样品的致密度随烧结温度的提高而增加; 当CaO掺杂量大于或等于0.5wt%时, 样品的致密度随烧结温度的提高而降低。提高烧结温度和添加CaO均能促进陶瓷相晶粒长大。样品在1250℃烧结时, 其抗弯强度在CaO掺杂量为1.0wt%时达到极大值为150.66MPa。