锂离子电池高温化成工艺研究

为缩短锂电池生产工艺时间、节约成本,高温压力化成受到工艺人员的关注,本文以钴酸锂-石墨体系的软包装锂离子电池为研究对象,研究了高温压力化成工艺中温度对化成效果的影响。在某一压力作用下,采用不同化成温度,分析了不同化成温度对应的实际化成时间、化成电压、电压降以及电池倍率放电与高温处理的性能,结果显示化成温度越高,化成时间越长;在不同的温度下化成,对电池的循环性能及倍率性能影响不同。

Microstructure and evolution of(TiB_2+Al_2O_3)/NiAl composites prepared by self-propagation high-temperature synthesis

（TiB2＋Al2O3）/NiAl composites were synthesized by self-propagation high-temperature synthesis, and their phase compositions, microstructures and evolution modes were studied. The microstructures and shapes vary with the TiB2＋Al2O3 content in the NiAl matrix. TiB2 particles take a great variety of elementary shapes such as white bars, plates, herringbones, regular cubes and cuboids. These results outline a strategy of self-assembly processes in real time to build diversified microstructures. Some TiB2 grains in sizes of 2-5μm are embeded in Al2O3 clusters, while a small number of TiB2 particles disperse in the NiAl matrix. It is believed that the higher the TiB2＋Al2O3 content is, the more the regular shapes and homogeneous distributions of TiB2 and Al2O3 will be present in the NiAl matrix.

Effect of extrusion process on microstructure and mechanical properties of Ni_3Al-B-Cr alloy during self-propagation high-temperature synthesis

The well-densified Ni3Al-0.5B-5Cr alloy was fabricated by self-propagation high-temperature synthesis and extrusion technique. Microstructure examination shows that the synthesized alloy has fine microstructure and contains Ni3Al, Al2O3, Ni3B and Cr3Ni2 phases. Moreover, the self-propagation high-temperature synthesis and extrusion lead to great deformation and recrystallization in the alloy, which helps to refine the microstructure and weaken the misorientation. In addition, the subsequent extrusion procedure redistributes the Al2O3 particles and eliminates the γ-Ni phase. Compared with the alloy synthesized without extrusion, the Ni3Al-0.5B-5Cr alloy fabricated by self-propagation high-temperature synthesis and extrusion has better room temperature mechanical properties, which should be ascribed to the microstructure evolution.

SAPO-34 synthesized with n-butylamine as a template and its catalytic application in the methanol amination reaction

SAPO-34 was synthesized with n-butylamine（BA） as a template for the first time.Crystallization temperature and initial Si amount were important factors leading to successful syntheses.Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures,though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature.Higher temperature（240℃） can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation.The crystallization processes at 200 and 240℃ were investigated and compared.We used the aminothermal method to synthesize SAPO-34-BA at 240℃ and also found n-propylamine is a suitable template for the synthesis of SAPO-34.The SAPO-34-BA products were characterized by many techniques.SAPO-34-BA has good thermal stability,crystallinity and porosity.BA remained intact in the crystals with ~1.8 BA molecule per chabazite cage.The catalytic performance of SAPO-34 was tested in the methanol amination reaction,which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated,suggesting that this material is a good candidate for the synthesis of methylamines.

Preparation of low-oxygen Ti powder from TiO_(2) through combining self-propagating high temperature synthesis and electrodeoxidation

An effective method was reported to prepare low-oxygen Ti powder,which included two experimental steps:the fast conversion of TiO_(2) to TiO_(x<1) powder by self-propagating high-temperature synthesis(SHS)process and the generation of low-oxygen Ti powder by electrodeoxidizing TiO_(x<1) powder at the cathode in molten CaCl_(2).The key intermediate steps were analyzed by XRD,SEM and electrochemical testing techniques.The results demonstrated that TiO_(x<1) powder(TiO_(0.325) and TiO_(0.97))was generated after acid leaching MgO in SHS products with TiO_(2)/Mg molar ratio of 1:2,and the TiO_(x<1) powder with 16.3 wt.%oxygen could be transformed into pure titanium powder with 0.121 wt.%oxygen by electrodeoxidation at a constant potential of−3.3 V for 10 h.The electrodeoxidation of TiO_(x<1) powder in CaCl_(2) molten salt follows the step-by-step deoxidation mode,and the lattice of TiO_(x<1) powder after electrodeoxidation shrinks.

Fluidized-bed pyrolysis of waste bamboo

Bamboo was a popular material substituting for wood, especially for one-off commodity in China. In order to recover energy and materials from waste bamboo, the basic characteristics of bamboo pyrolysis were studied by a thermogravimetric analyzer. It implied that the reaction began at 190-210℃, and the percentage of solid product deceased from about 25% to 17% when temperature ranged from 400℃ to 700℃. A lab-scale fluidized-bed furnace was setup to research the detailed properties of gaseous, liquid and solid products respectively. When temperature increased from 400℃ to 700℃, the mass percent of solid product decreased from 27% to 17% approximately, while that of syngas rose up from 19% to 35%. When temperature was about 500℃, the percentage of tar reached the top, about 31%. The mass balance of these experiments was about 93%-95%. It indicated that three reactions involved in the process： pyrolysis of exterior bamboo, pyrolysis of interior bamboo and secondary pyrolysis of heavy tar.

Preparation of Mo(Si,Al)_2 feedstock used for air plasma spraying

In order to prepare high quality Mo（Si,Al）2 feedstock characterized with C40 phase, higher Al doping amount andexcellent flowability, Mo（Si1-x,Alx）2 with different Al contents （x=0, 0.1, 0.2, 0.3, 0.4, 0.5） were synthesized by self-propagatinghigh-temperature synthesis first and Mo（Si0.6,Al0.4）2 was confirmed as the suitable material through X-ray diffraction analysis. Aseries of tests with different parameters of induction plasma spheroidization were applied to improving the flowability of feedstock.Mo（Si,Al）2 feedstock with excellent flowability （26.2 s/50 g） was prepared through adding hydrogen into sheath gas and decreasingthe powder feeding rate. The composition segregation occurred in the spheroidized powder after Al consumption and oxidation. Theinhomogeneous structure of the same particle was caused by the asymmetric heating and cooling when particle passed through theplasma jet.

Combustion synthesis of FeAl−Al2O3 composites with TiB2 and TiC additions via metallothermic reduction of Fe2O3 and TiO2

Combustion synthesis involving metallothermic reduction of Fe2O3 and TiO2 was conducted in the mode of self-propagating high-temperature synthesis(SHS)to fabricate FeAl-based composites with dual ceramic phases,TiB2/Al2O3 and TiC/Al2O3.The reactant mixture included thermite reagents of 0.6Fe2O3+0.6TiO2+2Al,and elemental Fe,Al,boron,and carbon powders.The formation of xFeAl−0.6TiB2−Al2O3 composites with x=2.0−3.6 and yFeAl−0.6TiC−Al2O3 composites with y=1.8−2.75 was studied.The increase of FeAl causes a decrease in the reaction exothermicity,thus resulting in the existence of flammability limits of x=3.6 and y=2.75 for the SHS reactions.Based on combustion wave kinetics,the activation energies of Ea=97.1 and 101.1 kJ/mol are deduced for the metallothermic SHS reactions.XRD analyses confirm in situ formation of FeAl/TiB2/Al2O3 and FeAl/TiC/Al2O3 composites.SEM micrographs exhibit that FeAl is formed with a dense polycrystalline structure,and the ceramic phases,TiB2,TiC,and Al2O3,are micro-sized discrete particles.The synthesized FeAl−TiB2−Al2O3 and FeAl−TiC−Al2O3 composites exhibit the hardness ranging from 12.8 to 16.6 GPa and fracture toughness from 7.93 to 9.84 MPa·m1/2.

Characteristics of MSWI fly ash during vitrification

The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350 ℃ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260 ℃. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260 ℃, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260 ℃. Heavy metals of Pb and Cd are almost vaporized above 1000 ℃. Cr is not volatile and its binding efficiency can reach 100% below 1000 ℃. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.

High Temperature Seedless Synthesis of Au NRs Using BDAC/CTAB Co-surfactant

Au nanorods have been successfully synthesized at 90 ℃ by using hexadecyltrimethylammonium bromide （CTAB） and benzyldimethylammoniumchloride hydrate （BDAC） co-surfactant. At 90 ℃, the reaction time was less than 10 s, and the longitudinal surface plasmon absorption band could vary between 680 and 770 nm by adjusting the molar ratio of BDAC to CTAB from 2 to 0.5. At 90 ℃, nanorods with a longitudinal surface plasmon absorption peak of 770 nm can be obtained when the molar ratio of BDAC to CTAB was 3：2.