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  • Volume 35,Issue 5,2006 Table of Contents
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    • Recent Development of Processing Map Theory

      2006, 35(5):673-677.

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      Abstract:Processing map is an effective tool for the optimization of materials workability, product property control and defect avoidance. Processing map is constructed by the superimposition of power dissipation efficiency and the instability maps, and can be divided into a safe domain and an unsafe domain. The developments of the Raj map and the processing map based on Dynamic Material Model (DMM) were reviewed in this paper. The DMM theory was introduced first, and then a comparison of different instability criteria were made to help to achieve a better control of microstructure during processing. Different deformation mechanisms, including dynamic recrystalli- zation, superplastic deformation, wedge cracking, formation of adiabatic shear bands and globulazation of lamella alpha were explained by the processing map based on DMM.

    • Recent Advances on Precision Casting of Large Thin Wall Complex Castings of Titanium Alloys

      2006, 35(5):678-681.

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      Abstract:In this paper the development and study status of precision casting for the large-thin wall-complex titanium alloys casts are introduced in the aspects of melting, precision casting and defect detecting. The correlated casting technologies and numerical simulation processing are presented. Development trend of the large-thin wall complex titanium alloy castings by precision casting is described.

    • Phase Structure and Hydrogen Storage Properties of Ti_(17)Cr_(23)V_(55-)xZr_5Fe_x (x=11~16) Alloys

      2006, 35(5):682-685.

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      Abstract:系統(tǒng)研究了Ti17Cr23V55-xZr5Fex(x=11~16)合金的相結構以及儲氫特性。XRD及SEM分析表明,所有合金的主相均為體心立方(bcc)結構的釩基固溶體,并含有σ-FeCr和Cr2Zr等第二相;隨著Fe含量的增加,合金中的bcc主相含量和晶胞體積逐漸降低,σ-FeCr相含量逐漸增多,而Cr2Zr相含量幾乎恒定。儲氫性能測試表明,該系列合金的活化性能和動力學性能都很好,在20℃和4MPa初始氫壓條件下首次吸氫即可活化,并且無需氫化孕育期就能快速吸氫。當Fe含量從x=11增加至x=16時,合金的室溫最大吸氫量從268ml/g逐漸降低至25lml/g,80℃有效放氫量從153ml/g逐漸降低至137ml/g。研究表明,為了改善合金的有效儲氫能力,必須消除合金中不吸氫的σ-FeCr相或者抑制σ-FeCr相的生成。

    • Hydrogen Storage Properties of V-Ti-Cr-Fe Alloys

      2006, 35(5):686-689.

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      Abstract:The hydrogen storage properties of V-Ti-Cr-Fe alloys with compositions of V(30 at%)-Ti(15 at%~55 at%)-Cr(7 at%~43 at%)- Fe(2 at%~18 at%) were studied in this paper. It is found that the hydrogen absorption capacities and the effective hydrogen capacities of the alloys are largely dependent on the Ti/(Cr+Fe) ratio. The alloy shows the largest effective hydrogen capacity at a Ti/(Cr+Fe) ratio of 1.0. With the increase of Ti/(Cr+Fe) ratio (0.9~1.05), the lattice parameters of the alloys and the enthalpy of hydrides grow, and the hydrogen desorbing plateau pressure declines. The alloy of V30Ti35Cr25Fe10 with 10at% Fe exhibits a hydrogen capacity of 3.6wt% and an effective hydrogen capacity of 2.0wt% at 298 K.

    • Oxidizing Characteristics and Oxide Formation of V-4Cr-4Ti Alloy

      2006, 35(5):695-697.

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      Abstract:研究了V-4Cr-4Ti合金的氧化動力學,采用XRD分析了在不同溫度下,合金表層氧化物的形成過程。結果表明;V-4Cr-4Ti合金在300℃~400℃范圍內,氧化速率很慢,氧化增重隨時間的增加基本保持不變,在500℃~600℃化速率顯著加快,其中600℃時的氧化增重是500℃時的10倍。表層氧化產物在400℃后逐漸形成,主要產物是V2O5。

    • Comparison of the Oxidation Behaviors of Zircaloy-4 Implanted with Cerium and Niobium Ions

      2006, 35(5):698-702.

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      Abstract:利用MEVVA源對Zr-4合金分別進行1×1016 ions/cm2至1×1017ions/cm2劑量的鈰離子與鈮離子注入,比較了Ce/Nb離子注入對Zr-4合金氧化行為的影響.結果表明,鈰離子注入可以較大程度地提高Zr-4合金的抗氧化性能,而鈮離子注入則在一定程度上使Zr-4合金的氧化性能下降.GAXRD分析顯示,鈰離子注入促進了氧化鋯由單斜相向六方相的轉變,但鈮離子注入卻對氧化鋯相的轉變沒有影響.并探討了Ce/Nb離子注入影響Zr-4合金氧化行為的機理.

    • Low Cycle Fatigue Behavior of Ti-1023 Titanium Alloy at Room Temperature

      2006, 35(5):703-706.

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      Abstract:Low cyclic fatigue behavior of Ti-1023 titanium alloy has been investigated under a fully reversed total strain-controlled mode. The strain-life and cyclic stress-strain data were analyzed to determine the individual strain fatigue parameters. It is found that the Ti-1023 alloy exhibited an initial slight cyclic hardening, followed by stable cycle at a total strain amplitude of 0.6%-0.8%, then cyclic softening at a total strain amplitude of above 0.8% to 3.0%. It is considered that the cyclic stress response behavior of Ti-1023 alloy depends on the total strain amplitude.

    • Influence of Solution Conditions on Aging Response of a New Metastable Beta Titanium Alloy

      2006, 35(5):707-710.

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      Abstract:根據近臨界鉬當量和多元強化原則設計了一種新型亞穩(wěn)β鈦合金(Ti-B20),以室溫拉伸性能和顯微組織為主要考察內容研究了固溶處理對這種新合金時效響應的影響。結果表明:在同樣的時效條件下,該合金的抗拉伸強度隨著固溶溫度的升高而升高,而固溶后水淬比空冷能產生更高的硬化效應,分析結果揭示了該合金獨特的時效響應來自于其亞穩(wěn)β相較低的穩(wěn)定性和過??瘴粚ξ龀龅墓餐饔?。

    • Effects of Heat Treatment on the Microstructures and Stress Rupture Properties in a Ni-Base Single Crystal Superalloy

      2006, 35(5):711-714.

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      Abstract:研究了不同熱處理工藝對一種鎳基單晶高溫合金的組織和持久性能的影響。結果表明:固溶處理時間越長,合金中的γ′相尺寸越均勻,有利于合金持久性能的提高。1080℃,4h和1150℃,4h時效后空冷獲得的γ′相具有尺寸適合、立方度高的特點。2種時效處理對合金中溫高應力的持久性能影響不明顯,在高溫低應力下,經1080℃時效處理的持久壽命略長。

    • Oxidation Behavior of NiAl-30.9Cr-3Mo-0.1Dy Alloy at High Temperature

      2006, 35(5):719-723.

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      Abstract:研究了NiAl-30.9Cr-3Mo-0.1Dy合金在1300K~1500K空氣中的恒溫氧化行為。結果表明:NiAl-30-9Cr-3Mo-0.1Dy合金的抗氧化性遠優(yōu)于NiAl-31Cr-3Mo合金:1500K的氧化動力學曲線基本遵循拋物線關系,在1350K~1450K的氧化動力學曲線符合立方拋物線關系,1300K的氧化動力學曲線則符合5次方關系。氧化過程中,合金的表面生成了連續(xù)致密的Al2O3氧化膜;稀土元素的活性作用以及Al2O3與基體合金之間的富Cr層的形成,提高了Al2O3的粘附能力。Dy的添加也減少了NiAl相上Al2O3的生成量,延緩了θ-Al2O3向α-Al2O3相的轉變時間。

    • Effects of Hydrogen on the Crystallization Process of Zr41.2Ti13.8Cu12.5Ni10Be22.5 Bulk Amorphous Alloys

      2006, 35(5):724-727.

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      Abstract:Zr41.2Ti13.8Ni10Cu12.5Be22.5 bulk amorphous alloy was prepared by arc-melting and rapid casting into a copper mould. Hydrogen charging was performed electrochemically in glycerine-phosphoric acid electrolyte. The effects of hydrogen on the crystallization process of Zr-Ti-Cu-Ni-Be bulk amorphous alloy were studied by differential scanning calorimetry (DSC), Kissinger equation and high-resolution transmission electron microscope (HRTEM). It is shown that hydrogen increases the activation energy of the glass transition and crystallization, and retards the nucleation and crystal growth. Moreover, hydrogen charging contributes to the formation of isolated crystals, resulting in the precipitation of fine and uniformly distributed nanocrystallines.

    • Nanocrystalline Formation in Zr52.5Cu27Ni5.5Al12Nb3 Amorphous Alloy and the Effect on Compress Mechanical Properties

      2006, 35(5):728-731.

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      Abstract:采用射流鑄造法在水冷銅模中制備出成分為Zr52.5Cu30-xNi5.5Al12Nbx(x=0,3)的塊體非晶合金。x=0時,樣品為完全非晶結構;x=3時,試樣的組織為非晶基體上均勻分布著尺度為20nm的富含Zr和Nb的成分偏聚區(qū),同時富集區(qū)內鑲嵌著尺寸為5nm左右bcc結構的Zr-Nb固溶體納米顆粒。Zr52.5Cu27Ni55Al12Nb3合金的強度較具有完全非晶結構的Zr52.5Cu3027Ni55Al12合金有明顯的提高:斷裂強度由1600MPa增加到1964MPa。非晶基體上析出的納米顆粒和成分偏聚增加了剪切變形的阻力。同時,基體變形由單滑移(x=0)轉變?yōu)槎嗷疲▁=3),并且滑移相互交錯,避免了由于不均勻形奪誥成的據前脆斷。提高了基體的強度。

    • Microstructural Evolution of the Deeply Undercooled Ag-Ge Alloys with Cu Atoms Cluster Triggered Nucleation

      2006, 35(5):732-735.

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      Abstract:The Ag-Ge alloy melts with deeply undercooled hypoeutectic, eutectic and hypereutectic were obtained via glass fluxing technique. The nucleation of the deeply undercooled alloy melts were triggered by atoms cluster sputtering on the surface of the melts. The atoms clusters were generated by an ion beam bombarding on the Cu foil fixed above the alloy melts. The resultant microstructure reveals that the induced atom clusters exert great influence on the microstructural evolution of the highly undercooled eutectic and hypereutectic Ag-Ge alloys, but no obvious influence on the highly undercooled hypoeutectic alloy. The microstructural evolution and formation mechanism were analyzed and discussed.

    • Physical Chemistry Questions on the Purification of Rare Earth Yttrium by Electrochemical Deoxidation

      2006, 35(5):736-739.

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      Abstract:在電化學脫氧提純金屬釔的過程中,利用熔融的CaCl2使其副產品CaO的活度降低,脫去的氧以CO或CO2氣體的形式從石墨陽極放出,只要電解條件合適,可使脫氧極限無限降低,同時金屬鈣是由CaCl2電解所得,較Ca—CaCl2熔鹽脫氧提純金屬釔的方法,它降低了由于金屬Ca的不純而引入的雜質污染。對于形狀規(guī)則的金屬釔脫氧時間為t=(d^2/π^2D)ln[(4c0/nc)sinπx/d]。脫氧后的產品有少量的碳污染,但對實驗進行一定的改進后,也可得到氧含量和碳含量都低于100μg/g的金屬釔。

    • Effect of Zr Element on the Structure of Sm2Fe17 Alloys

      2006, 35(5):746-748.

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      Abstract:通過XRD,SEM,EDX等手段研究了Zr對Sm2Fe17母合金及均勻化熱處理后合金的相及微觀結構的影響。結果表明:少量Zr元素的加入,能有效抑制鑄錠中α-Fe相的生成:改變富Sm相的分布形態(tài),使其在合金中沿基體Sm2Fe17相晶界呈網狀分布,同時能部分取代基體Sm2Fe17相中Fe;短時的熱處理能進一步降低合金中α-Fe含量在消除富Sm相,并使Zr在合金中的分布趨于均勻,而長時間熱處理對加Zr合金不是一個必要的環(huán)節(jié)。因此,Zr元素的加入有效的降低了成本,有利于制備成分均一的高質量的Sm2Fe17相母合金。

    • Research on Magnetocaloric Effect of GdAl Alloy

      2006, 35(5):749-751.

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      Abstract:對成本較低、抗氧化性好的GdAl磁制冷工質材料制作工藝和性能進行了研究。比較了鑄錠法和熔體快淬法對磁制冷工質材料組織結構和性能的影響。用直接測量法測其在外加磁場為1.2T,溫度變化范圍在-10℃~30℃下的磁熱效應。結果表明:熔體快淬法制備的磁工質材料晶粒尺寸小于鑄錠法,但其磁熱效應和居里溫度均低于鑄錠樣,原因是熔體快淬法制備的磁制冷工質材料中相結構發(fā)生變化,磁熱效應優(yōu)良的Gd3Al2相減少,性能較差的GdAl3相增加。同時,與鑄錠組織相比,細晶組織內部出現(xiàn)大量的晶界,晶界處原子排列的無序度增加,材料的比熱升高,導致磁熱效應降低。再者,細晶晶界處的原子密度和配位數(shù)遠遠偏離了完整晶體的晶體結構,從而使配位數(shù)Z降低而導致居里溫度降低。

    • DTA and TMA Analyses of AZ91D Magnesium Alloys

      2006, 35(5):752-756.

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      Abstract:采用差熱分析(DTA)和熱機械分析(TMA)技術以及光學顯微鏡和X射線衍射(XRD)研究了常規(guī)凝固和快速凝固條件下的AZ91D鎂合金及其熱擠壓型材的相轉變溫度和線膨脹規(guī)律,探討了其組織特征與熱物性的關系。結果表明:常規(guī)凝固的AZ91D鎂合金擠壓前后在450℃左右均有明顯的DTA峰,由于快速凝固薄帶為單相過飽和α-Mg固溶體,熱擠壓過程中Al的脫溶而析出彌散分布的β-Mg17Al12相含量極少,因此快速凝固薄帶及其熱擠壓的型材均無明顯的DTA峰。AZ91D鎂合金的線膨脹系數(shù)并非線性變化,在225℃前熱擠壓AZ91D鎂合金型材的線膨脹系數(shù)波動幅度最低。熱擠壓后型材的熱膨脹系數(shù)遠小于鑄態(tài)的熱膨脹系數(shù)。

    • Effects of Impurities on the Damage and Property for HfO2 Coating Material

      2006, 35(5):757-760.

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      Abstract:By analysis of impurity elements in HfO2 coating material, the influence of main impurity elements on the characteristic of coatings were studied. The results indicate that the metal elements and absorptive dielectric elements damage the HfO2 coatings. The more the Zr element content is, source center and form an the more the absorption is for the coatings in ultraviolet wave. The negative ion element will become the gas ejection in the process of evaporation of coating material, so decrease the damage threshold of the coatings.

    • Sensitivity Analysis on Reliability for the Crack Growth Life of Powder Metallurgy Turbine Disk

      2006, 35(5):761-765.

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      Abstract:Based on residual strength interference model and life interference model, a sensitivity analysis method on reliability was proposed for the fatigue crack growth life of powder metallurgy materials. The characteristics were considered on the multiple inclusions in the powder metallurgy materials, especially on the sensitivity analysis method. The relationship of sensitivity for the system failure probability was firstly constructed between multiple failure modes and single failure mode. The advanced method of first order and second moment was employed to calculate the partial derivatives of the system failure probability for the distribution parameters of the process variables and some basic variables. Then by use of regression analysis and numerical property of process variables, the sensitivities of parameters were derived for the process variables and basic variables. Finally, the sensitivities of system failure probability to the distribution parameters of the total basic variables were obtained. Then the proposed reliability sensitivity model was applied to a powder metallurgy turbine disk. The reliability sensitivity results show that the system failure probability of the turbine disk is significantly influenced by the crack growth coefficient c1 of Paris law at a given condition, and the essential relationship is clarified between the model and the distribution parameters. It is proved that the model might supply guidance to the design of powder metallurgy turbine disks. The calculated results were consistent each other with the residual strength interference model and the life interference model, and showed the feasibility of the proposed analysis method from the good agreement between the quantity calculation and the quality analysis.

    • Long Afterglow Property and Mechanism on Gd2O2S:Ti

      2006, 35(5):766-769.

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      Abstract:利用高溫固相法合成了一種長余輝發(fā)光材料Gd2O2S:Ti,利用XRD測試了其結構并測試了其在紫外光激發(fā)下的發(fā)光特性;停止照射,有橙色的余輝,時間接近2h。分析該磷光體的發(fā)光和余輝產生細節(jié),認為空穴和電子的復合導致Ti^3+的^2E→^2T2的躍遷是產生發(fā)光和余輝的原因;并根據缺陷和空位對Gd2O2S:Ti的余輝機理進行探討,提出了余輝機理模型。

    • Tensile Failure Behavior of Metal Foams under Uniaxial and Biaxial Loads

      2006, 35(5):770-773.

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      Abstract:In the present work, the low-load uniaxial and biaxial tensile testers were employed to carry out the uniaxial and biaxial tensions systemically for porous metal bodies at different uniaxial and biaxial tensile rates. The uniaxial tensile failure mechanism is analyzed, and the results show that the macroscopical failure behavior of the foam metals with open cells differ from either the transverse rupture by maximum tensile stress criterion, or the plastic flow failure by maximum shearing stress criterion, but behaves a complicated failure mode between these two criterions. In addition, the percentage elongation after fracture results mainly from the plastic deflexion of metallic struts within the three-dimensional reticulated structure, hardly from the plastic deformation of the metallic body under uniaxial tension. From the fracture morphologies under biaxial tension, it is found that the distribution of the stress field in the cruciform specimens of the foamed metal under biaxial equal-speed tension is similar to that under biaxial unequal-speed tension, and the maximum stress line of the stress field presents the four-fold symmetric curved-side tetragon.

    • Theoretical Models of the Thermal Stress Evolution Mechanism during Quenching of No Phase Transformation Alloy--(2) The Surface and Center Model for Thermal Stress during Quenching and the Dynamic Film Effect during Quenching

      2006, 35(5):774-778.

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      Abstract:In this paper, 3 types of surface modes and 2 types of center modes and their practical applications were proposed and analyzed for the thermal stress analysis during quenching for no phase transformation alloy. And the 2D and 3D boundary and comer models without corner effect and their practical applications during quenching were also established and analyzed. The dynamic film effect, the phenomenon of dynamic wave of fathom line vs temperature, temperature gradient, thermal stresses and shape of plastic deformation zone were proposed. Also the thermal stress distribution, important to the technology, was analyzed with/without consideration of dynamic film effect. The relationship between the dynamic film effect and the comer effect during quenching was also analyzed.

    • Effect of Hydrogen-Charged Treatment on the Biaxial Cyclic Deformation Behavior of Cold-Worked Ziraloy-4

      2006, 35(5):783-786.

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      Abstract:研究了不同程度滲氫處理Zr-4合金的雙軸循環(huán)變形行為。結果表明:當氫含量為CH=400μg/g時,在相同等效應變幅和相同相位角下,滲氫Zr-4合金的疲勞壽命高于原始冷變形狀態(tài)Zr-4合金。當氫含量增加到CH=580μg/g時,滲氫處理Zr-4合金的雙軸疲勞壽命卻低于原始冷變形狀態(tài)的Zr-4合金。透射電鏡和金相顯微鏡觀察表明,冷變形Zr-4合金滲氫后析出的氫化物具有良好的塑性變形能力,滲氫過程中中溫條件下長時間保持導致基體產生去應力退火效應是Zr-4合金疲勞壽命提高的主要原因。

    • Synthesized in situ Ti-Al Intermetallic Composite Reinforced with Autogenous Alumina Fibers

      2006, 35(5):791-794.

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      Abstract:Ti-Al intermetallic composile with Al2O3 fiber interpenetration was fabricated in situ in slight-oxidizing atmosphere by the heat-treatment of the prefabricated pieces consisted of Ti, Al and other trace metallic elements. The final phases composition and mierostrueture were analyzed by XRD and SEM. The principle of the synthesis process and the influertce of the processing parameters on the mierostructure development were investigated in order to study whether the Al2O3 fiber would exist and what kind of matrix phases would be formed easily according to the molar ratio of components and the processing parameters.

    • Microstructure and Mechanical Properties of Al-40Si Alloy Prepared by a Mixed Solid-Liquid Casting

      2006, 35(5):795-797.

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      Abstract:采用固液混合鑄造的Al-40Si合金組織細小,合金力學性能明顯優(yōu)于傳統(tǒng)鑄造和半固態(tài)加工合金,并且解決了傳統(tǒng)鑄造Al-40Si合金鑄件難以熱加工的問題。在本工藝條件下,當添加平均粒度為120μm的粉末且粉末添加量與合金熔體質量比為1時,Al-40Si合金中的初晶硅平均粒度可控制在30μm以下;材料的室溫力學性能為:σb=119.6MPa,σ0.2=105MPa,δ=1.43%。

    • Effect of Lanthanum Metals Doping on the Magnesium Nickel Hydrogen Storage Alloys Synthesized by Hydriding Combustion

      2006, 35(5):798-801.

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      Abstract:借助于XRD,TG-DSC等技術研究了摻雜鑭系金屬對氫化燃燒合成鎂鎳儲氫合金合成條件及合金性能的影響。結果表明:摻雜鑭系金屬的試樣在氫氣壓力為2.0MPa,600℃下保溫2h可大量形成Mg2NiH4;氫氣壓力越大,形成Mg2NiH4越多;過高的合成溫度和過長的保溫時間極不利于Mg2NiH4的形成;鑭系金屬的摻入使Mg2NiH4晶胞發(fā)生了一定的畸變;摻雜鑭系金屬的Mg2NiH4放氫溫度為271.7℃左右,比未摻雜的降低了110℃左右;摻雜鑭系金屬試樣的總放氫量可達3.21%(質量分數(shù),下同);摻雜鑭系金屬的試樣在300℃,0.1MPa下的放氫時間為7min~8min;活化可適當提高吸放氫量。

    • Dehydriding Kinetic Mechanism of MgH2 Prepared by Catalytic Synthesis under Atmospheric Pressure

      2006, 35(5):802-805.

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      Abstract:The dehydriding kinetics for MgH2 material synthesized by catalytic method under atmospheric pressure has been studied experimentally. A new kinetic model has been used to describe the curve tendency of the reacted fraction vs. time, to calculate the apparent activation energy of dehydriding reaction and to explain why this catalytic synthesis method can get a good kinetic result.

    • Study on the Tribological Behavior of Micro-arc Oxidized Ceramic Coatings on Magnesium Alloy Surfaces

      2006, 35(5):806-809.

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      Abstract:利用微弧氧化技術在AZ31鎂合金表面原位生長陶瓷層,用球-盤磨損實驗機對試樣的摩擦學性能進行了研究。結果表明:AZ31鎂合金表面微弧氧化后可以形成均勻的表面陶瓷改性層,改性層由疏松層、致密層和截面層組成,厚約20μm。微弧氧化處理后的試樣在干摩擦小滑動距離下表現(xiàn)出良好的耐磨性。并用SEM,XRD分析了微弧氧化陶瓷層的顯微組織、表面形貌和相結構。

    • Synthesis of NiO-SDC Composite Powders for Anode by Glycine-Nitrate Process

      2006, 35(5):810-813.

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      Abstract:采用甘氨酸-硝酸鹽燃燒法合成了中溫固體氧化物燃料電池NiO-SDC復合陽極粉末。通過XRD和掃描電子顯微鏡對不同甘氨酸/金屬離子摩爾比合成的復合粉末的結構和形貌進行了研究。XRD結果表明,直接燃燒合成的復合粉末除了NiO和CeO2的衍射峰外,還有Ni2O3衍射峰存在,粉末經900℃煅燒2h后Ni2O3峰消失,表明形成了NiO-SDC復合陽極粉末。氫氣條件下的熱重分析表明,復合粉末中NiO和SDC兩相比例與溶液組分配比基本一致。制備的不同NiO含量薄膜陽極的電解質支撐單電池性能測試結果表明,陽極為60%NiO-SDC的單電池具有最高的開路電壓。

    • Fabrication Research of Silver Copper Oxide Composite Reactive Synthesis

      2006, 35(5):814-816.

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      Abstract:Silver copper oxide composites were prepared by reactive synthesis and powder metallurgy methods, Microstructures and properties of silver copper oxide composites by the two methods were studied in the present paper. The results show that silver copper oxide fabricated by reactive synthesis possess unique ringed microstructure that brings its good mechanical and alternating current contact properties. It means that reactive synthesis method can obtain better mechanic properties than powder metallurgy method in fabrication silver copper oxide composites. The service life of Ag/CuO material with reactive synthesis was twice as long as it with powder metallurgy under AC (220 V) and DC (24 V).

    • Coating Structure and Antioxygenation of Micron Ni-Ag Bimetallic Powder

      2006, 35(5):817-819.

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      Abstract:采用化學鍍法在鎳粉表面包覆一層金屬銀,然后將這種包覆粉進行真空熱處理,即可制得具有抗氧化作用的微米級鎳-銀雙金屬粉末。用SEM、XRD、粒度分析和熱重分析表征不同包覆厚度的雙金屬粉和原始鎳粉的表面形貌、包覆結構及其抗氧化性。結果表明:鎳粉表面包覆的銀越多,雙金屬粉形狀越規(guī)則,表面包覆層越致密,雙金屬粉的抗氧化溫度也就越高,顆粒表面銀含量為76%(質量分數(shù),下同)時,其抗氧化溫度可以達到850℃。

    • Preparation of IrO2 Thin Films by Pulsed Laser Deposition

      2006, 35(5):820-823.

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      Abstract:利用脈沖激光沉積(PLD)技術,在Si(100)襯底上制得了導電氧化銥(IrO2)薄膜.討論了沉積參數(shù)(O2分壓、襯底溫度)對IrO2薄膜的結構、表面形貌和導電性的影響.結果表明20 Pa為最佳O2分壓、400℃~500℃為適宜的沉積溫度,此條件下制得的IrO2薄膜結晶完整,組織均勻、形狀一致,排列致密,其最低電阻率約為42μΩ·cm.

    • New Super Hard Ti-Si-C-N Nanocomposite Coatings Deposited by Pulsed DC Plasma CVD

      2006, 35(5):824-827.

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      Abstract:用工業(yè)型脈沖直流等離子體化學氣相沉積(PCVD)設備,在高速鋼(W18Cr4V)基材表面沉積新型四元Ti-Si-C-N復合超硬薄膜。結果表明:Ti-Si-C-N薄膜是由面心立方結構的TiN和TiC納米晶、Ti(C,N)固溶體及存在于晶界的非晶Si3N4和α-C組成,形成TiN/TiC/Ti(C,N)/α-C/α-Si3N,復相結構,這種復相結構存在著[111],[220]和[200]混合擇優(yōu)取向。SiCl4和CH4流量變化是影響薄膜相組成和硬度變化的主要工藝參數(shù)。隨Si含量的增加,薄膜的顯微硬度先升后降,表面形貌由致密的細顆粒狀變?yōu)榇执蟮闹l狀;C元素的加入能抑制柱狀晶的形成,對硬度影響較小。

    • A Study of Photocatalysis Activity and Microstructure of Titanium Dioxide Thin Films Precoated with CuO

      2006, 35(5):828-831.

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      Abstract:TiO2 thin films pre-coated with CuO can induce the formation of their rutile type structure. The pre-coating process was completed through the deposit of TiO2 sol-gel onto a glass substrate smeared with a layer of Cu(CH3COO)2 solution. The photocatalysis activity of the TiO2 thin films obtained was improved significantly. When a Cu(CH3COO)2 solution of 1(wt)% was used in the so-called pre-coated process, the activity of formed thin films reached their maximum, 53% higher than the untreated TiO2 thin films. Experimental results reveal that the greater the deformation of TiO2 lattice and the more the rutile type structure in the thin films, the higher the photocatalysis activity the thin films possess. SEM shows that the particle size of TiO2 films pre-coated with CuO is finer than that of the original films. XPS analysis demonstrates the Ti3+ content in the TiO2 thin films increases also when pre-coated with CuO.

    • Preparation and Characterization of Highly Preferred Orientation TiB2 Coatings

      2006, 35(5):832-835.

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      Abstract:Highly preferred orientation TiB2 coatings were obtained by electrochemical techniques of continuous current plating (CCP) and pulse current plating (PCP) in fluoride-chloride electrolytes (KF-KCl) containing K2TiF6 and KBF4 as the electrochemically-active components. The effects of cathode current density on the crystal size, preferred orientation, micro stresses and lattice constants were studied by X-ray diffraction (XRD). The results indicate that the crystal size gets smaller with the increase of the cathode current density due to the increase of the nucleation rate at the over-potential. Compared with the CCP, the crystal size of TiB2 coatings prepared by PIC is finer because PIC can weaken the concentration polarization and increase the nucleation rate by increasing the ion concentration of diffusion layer. The preferred orientation of TiB2 coatings prepared above is (001) plane at the experimental conditions, which can be well explained by the two-dimension crystal nuclei theory. The lattice constant of TiB2 coatings deviates from the theoretical value due to the stress in coatings. Besides, it is confirmed that the binding between TiB2 coatings and graphite substrates is the physical binding from the results of thermodynamic predictions, XRD and EDS (Energy Dispersive X-ray Spectrum). The existence of some cracks at the interface may be attributed to the difference between the thermal expansion coefficients of TiB2 and graphite.

    • Research on Structure and Properties of LiCoO2 Prepared from Spent Lithium Ion Batteries

      2006, 35(5):836-840.

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      Abstract:以從廢舊鋰離子電池中回收的鈷鋰為原料,Na2CO3為沉淀劑,聚乙二醇為分散劑,用共沉淀法制備了LiCoO2粉體.用DSC-TG對前軀體進行了差熱分析.結果表明在煅燒過程中有3次明顯的失重,650℃以后失重曲線趨于平直.用XRD對LiCoO2進行了晶相分析,在750℃制備的LiCoO2晶格常數(shù)為a=2.810 13×10-10m,c=14.034 6×10-10m,c/a=4.994 29,接近于標準LiCoO2的晶格常數(shù).用BET分析了LiCoO2的粉體比表面積,其值為18.55 m2/g,并通過SEM觀察到平均顆粒半徑為70 nm左右,屬于納米級粉體.首次充電容量達146 mA/hg,放電容量達142 mAh/g,10次循環(huán)后仍保持96%的放電比容量.

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