内氧化Al2O3／Cu—Cr复合材料工艺与性能的研究

通过对Al2 O3 Cu Cr复合材料内氧化粉末冶金工艺的优选 ,探讨了添加合金元素Cr对复合材料性能的影响。研究表明 ,弥散分布的Al2 O3 硬颗粒对基体具有明显的强化作用 ;加入适量的Cr所产生的沉淀强化作用进一步提高了材料的力学性能。实验表明 :Al2 O3 Cu Cr复合材料经过 10 0 0℃× 1h固溶处理 ,30 0℃× 2h时效 ,硬度达到 144HV ,比电导率为 6 6 7%IACS。根据实验结果 ,分析了弥散强化和沉淀强化共同作用下材料性能变化的趋势     

Al2O3/Cu复合材料的高温拉伸性能研究

Al2O3弥散强化铜基复合材料(Al2O3/Cu复合材料)因其具有优良的高强度高导电性能以及抗高温软化性能而成为备受瞩目的一种工程材料.本文研究了Al2O3/Cu复合材料的室温和高温拉伸性能及微观组织.研究表明该材料相比Cu-Cr合金(Cr0.7%wt)具有优越的高温强度.微观组织观察表明该材料高温下优越的强度主要是因为弥散而细小的Al2O3颗粒的存在阻碍了位错运动,抑制了晶粒长大和Cu基体的再结晶.动态回复和局部再结晶是主要的软化机制.断裂特征表现为局部韧性断裂.)     

时效处理对Al2O3/CuCrZr复合材料干摩擦磨损性能的影响

通过粉末冶金结合热挤压工艺制备出Al2O3颗粒增强Cu-Cr-Zr基复合材料,研究了时效处理工艺对该复合材料干摩擦磨损行为的影响.结果表明,经过480℃×1h时效处理后,在复合材料的基体中形成细小弥散的共格沉淀相,使其硬度提高并得到良好的导电性能.加入Al2O3颗粒显著提高了复合材料的耐磨性和摩擦的平稳性.磨损机理分析表明,恰当的时效处理工艺使复合材料基体的力学性能提高,摩擦过程中亚表层变形程度显著降低,避免了严重粘着转移的发生,改善了复合材料的耐磨性能.     

Al2O3/Cu复合材料的高温拉伸性能研究

Al2O3弥散强化铜复合材料(ADSCC)因其具有优良的高强度高导电性能以及抗高温软化性能而成为备受瞩目的一种工程材料.研究了ADSCC的微观组织和拉伸性能.研究表明该材料相比Cu-Cr合金(Cr0.7%)在高温下具有很高的强度保持比.材料的强度随温度的升高而下降.对ADSCC的微观组织研究表明该材料的强度高主要是因为Al2O3颗粒的弥散分布限制了位错运动,阻碍了晶粒长大和Cu基体的再结晶.动态回复和局部再结晶是主要的软化机制.断裂特征表现为局部韧性断裂.     

真空热压烧结Al2O3/Cu-Cr复合材料的组织与性能

采用简化内氧化真空热压烧结工艺制备了不同Cu2O加入量(4%、5%、6%)的Al2O3/Cu-Cr复合材料.分析研究了其微观组织与性能,并研究了冷变形对材料性能的影响.结果表明,在铜基体上弥散分布着细小粒状Al2O3颗粒,其粒径为5~20 nm,颗粒间距为20～150 nm;Al2O3/Cu-Cr复合材料经80%变形后,其硬度和抗拉强度明显提高,而电导率则随变形量的增大先升高后降低;随着Cu2O加入量的增加,材料的抗软化性能逐渐提高;当Cu2O加入量为5%时,真空热压烧结(950 ℃,2 h,22 MPa)后全部完成内氧化,且变形后综合性能最优,此时Cu2O含量为最佳的添加量.     

氧化剂含量对Cu-Al2O3/Cr复合材料组织与性能的影响

采用简化内氧化真空热压烧结工艺制备了不同氧源(Cu2O)含量(4%、5%、6%)的Cu-Al2O3/Cr复合材料(以Al2O3弥散强化铜为基体的Cu-Cr复合材料).用SEM、TEM等分析手段对所制备复合材料烧结态的微观组织及性能进行了研究.结果表明,在铜基体上弥散分布着大量细小的γ-Al2O3颗粒,其粒径为5～20nm,颗粒间距为20～150hm,当氧源含量为5%时,经真空热压烧结(950℃,2h,22MPa)后全部完成内氧化,此氧化剂含量为最佳的内氧化氧化剂添加量.     

反应热压法制备Al2O3/NiCrAl复合材料及功能梯度材料

采用NiO、Al和Cr粉末反应热压制备了Al2O3/NiCrAl复合材料,NiCrAl合金由NiO还原出来的Ni与添加的Cr和Al反应形成.制备了不同Al2O3含量的Al2O3/NiCrAl复合材料,并以Al2O3体积分数分别为25%、52.2%和75%的Al2O3/NiCrAl复合材料为过渡层制备了Y稳定氧化锆(YSZ)到NiCrAl合金的功能梯度材料.X射线衍射分析、金相观察、硬度测量和热循环冲击实验结果表明:用该方法制备的复合材料由Al2O3陶瓷相和(Ni,Cr,Al)固溶体组成,而Al2O3颗粒由NiO与Al原位反应形成,尺寸细小,呈弥散分布.该功能梯度材料经从室温到1 000℃空气中10次热循环后未发现有裂纹,表明该方法制备的材料陶瓷相与合金相有良好的相容性、较高的结合强度、良好的耐高温抗氧化及热循环冲击性能.     

Cr3C2/Ni3Al复合材料的高温稳定性

通过对Cr3C2/Ni3Al复合材料在1000℃进行长期时效和氧化实验,分别考察了该材料的高温相稳定性和化学稳定性.结果表明,经1000℃长期时效后,Cr3C2/Ni3Al复合材料中的Cr3C2强化相保持稳定,而基体中则析出一定量的γ相,该相的析出强化了Ni3Al基体,从而使得复合材料的硬度得到进一步提高.Cr3C2/Ni3Al复合材料具有优良的高温抗氧化性能,其表面形成以α-Al2O3为主的致密氧化膜,在空气中的氧化速率仅为Ni3Al合金的1/2.分析认为,Cr3C2在堆焊过程中发生溶解,导致部分Cr固溶于Ni3Al合金基体中,促进了α-Al2O3的形成,从而改善了复合材料的抗氧化性.Cr3C2具有良好的高温化学稳定性并与Ni3Al基体有较好的氧化协同性,从而可得到基体有力支撑以发挥抵抗磨损的作用.优良的高温稳定性使得Cr3C2/Ni3Al复合材料适于在1000℃的高温环境下长期服役.     

Al2O3弥散强化铜/铬复合材料的强化机理

采用简化内氧化-真空热压烧结新工艺制备了不同氧化剂Cu2O含量的Al2O3弥散强化Cu-Al2O3/Cr复合材料,考察了塑性变形和氧化剂含量对抗拉强度和显微硬度的影响,并通过扫描电子显微镜和透射电子显微镜分析了其微观组织,在此基础上综合分析了该复合材料的强化机理,并定量计算了各种强化因素的增强效果.结果表明:简化内氧化-真空热压烧结新工艺成功制备了基体晶粒细小的Cu-Al2O3/Cr复合材料;氧化剂Cu2O含量为5％时Cu-Al2O3/Cr复合材料的抗拉强度和硬度较高,且均随着变形量的增加而增加;细小的Al2O3颗粒的弥散强化和Cr颗粒相的聚集强化是该复合材料强化的主要原因,形变强化对其强化有一定贡献.     

内氧化制备Cu/Al2O3弥散强化铜的组织性能研究

实验用Cu2O粉作氧化剂,采用简化的内氧化法工艺,在900℃下使Cu-Al合金薄平板内氧化,获得Cu/Al2O3复合材料。研究不同氧化时间(3、6、10 h)下的Cu/Al2O3复合材料的组织特征及性能。研究表明:复合层中Al2O3颗粒呈弥散状分布;复合层表面和内部的晶粒大小明显不同,由于表面Al2O3析出较早,阻止晶粒的充分长大;表面晶粒较小,表面硬度随时间延长而升高。     

X-ray diffraction study of Ba0.985Na0.015Ti0.985Nb0.015O3, Ba0.6Na0.4Ti0.6Nb0.4O3 and Ba0.3Na0.7Ti0.3Nb0.7O3 compositions

The Ba_0.985Na_0.015Ti_0.985Nb_0.015O₃, Ba_0.6Na_0.4Ti_0.6Nb_0.4O₃ and Ba_0.3Na_0.7Ti_0.3Nb_0.7O₃ compositions of the (1 − x) BaTiO₃–xNaNbO₃ (BTNNx) system have been studied by X-ray diffraction and by measurements of dielectric properties. The specimens with composition BTNN (x = 0.015, 0.40 and 0.70) have been refined by the JANA program from X-ray powder diffraction data. Ceramic samples with composition (1 − x) BaTiO₃ + xNaNbO₃ (where x = 0.015, 0.40 and 0.70) were prepared by calcinations from appropriate mixture of BaCO₃, TiO₂, Na₂CO₃ and Nb₂O₅. The calcined powder was sintered at temperature range 1200–1400 °C. As the composition x increased from 0.015 (and 0.70), the ferroelectric ceramics (x = 0.015, FE) with tetragonal phase changed to the ferroelectric relaxors (RFE, x = 0.40). RFE ceramics showed a peculiar diffuse phase transition and dielectric relaxation at the low temperature (down to 180 K) due to a frustration between RFE and FE state. These ceramics present the classical ferroelectric character when 0 ≤ x < 0.075 and 0.55 < x ≤ 1 and relaxor character when 0.075 ≤ x ≤ 0.55.     

Magnetic, electrical and plastic properties of Fe76Nb2Si13B9, Fe75Ag1Nb2Si13B9 and Fe75Cu1Nb2Si13B9 amorphous alloys

Influence of 1 h annealing in vacuum on magnetic, electrical and plastic properties of Fe₇₆Nb₂Si₁₃B₉, Fe₇₅Ag₁Nb₂Si₁₃B₉ and Fe₇₅Cu₁Nb₂Si₁₃B₉ melt spun ribbons were carefully investigated. It was shown that in all cases soft magnetic properties can be significantly enhanced by applying 1-h annealing at characteristic temperatures T_op. This optimization annealing causes that permeability increases more than 15-times and magnetic losses (tangent of loss angle) achieves a minimum in relation to the as quenched state. Using structural examinations (X-ray and HRTEM) it was shown that for the Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy the optimized microstructure corresponds to a nanocrystalline αFe(Si) phase whereas in other alloys to a relaxed amorphous phase free of iron nanograins. As a consequence of this fact the Fe₇₆Nb₂Si₁₃B₉ and Fe₇₅Ag₁Nb₂Si₁₃B₉ alloys show higher plasticity in comparison to the nanocrystalline Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy. Temperatures of the first stage of crystallization, and related diffusion parameters were determined using measurements of resistivity versus temperature with different heating rates.     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

New Zr6CoAs2-type compounds: Y6CoBi2, Ho6CoBi2 and Tm6CoBi2

Results of a powder X-ray diffraction investigation of new ternary compounds are reported. The compounds Y₆CoBi₂ [a=0.8312(1) nm, c=0.4144(1) nm], Ho₆CoBi₂ [a=0.8246(2) nm, c=0.4095(1) nm], and Tm₆CoBi₂ [a=0.8155(2) nm, c=0.4066(1) nm] crystallize in the hexagonal Zr₆CoAs₂-type structure (space group P6b2m No. 189). The Zr₆CoAs₂-type structure is a superstructure of the Fe₂P-type structure.     

Zur Kenntnis von RbBa3Ca4Cu3V7O28

Single crystals of RbBa₃Ca₄Cu₃V₇O₂₈ were prepared above the melting point of the reaction mixture. It crystallizes with hexagonal symmetry, space group C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ is the second member of a new structure type of the copper-oxovanadates. Ba²⁺ shows an unusual 12-fold coordination. The two calcium positions are coordinated by trigonal prisms and octahedra respectively. The copper coordination is characterized by a stretched square pyramid. The Cu²⁺ ions are outside the centre nearly in plane of the pyramids.

Zusammenfassung

Einkristalle von RbBa₃Ca₄Cu₃V₇O₂₈ wurden oberhalb des Schmelzpunktes der Reaktionsmischung erhalten. Die Verbindung kristallisiert hexagonal, Raumgruppe C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ ist das zweite Beispiel für einen neuen Strukturtyp der Kupfer-Oxovanadate, mit 12-fach koordinierten Ba²⁺ -Ionen. Die zwei Calciumpositionen sind trigonal prismatisch bzw. oktaedrisch koordiniert. Die Koordination der Cu²⁺-Ionen ist durch eine gestreckte Pyramide charakterisiert. Cu²⁺ ist auβerhalb des Polyederzentrums nahezu in der quadratischen Fläche der Pyramide angeordnet.     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。     

电弧喷涂制备Fe65Cr20Mo7B3.5SiMn1.5W3涂层

在Q235低碳钢板上利用电弧喷涂工艺进行喷涂,以制得Fe65Cr20Mo7B3.5SiMn1.5W3涂层。喷涂材料为自行配制的丝材,按照35%的填充率将配好的粉填充到U型不锈钢外皮中,经过多道拉拔、挤压工艺制成Φ2mm的粉芯丝材。采用X射线衍射仪、扫描电镜、能谱分析仪、透射电镜对涂层的物相和组织形貌及成分进行了表征;采用差示扫描量热仪、显微硬度仪等设备对涂层的热稳定性及显微硬度进行了检测和分析。试验结果表明:涂层组织形貌呈典型的层状组织结构,由变形良好的带状粒子相互搭接堆积而成。涂层含有50.63%的非晶相,同时含有纳米级的晶相。涂层组织均匀、结构致密、孔隙率低,并且涂层硬度高达1040.5HV0.3,属硬质涂层,具有良好的热稳定性。     

Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

Spinel compound LiNi_0.4Mn_1.5Cr_0.1O₄ (LNMCO) and Li₄Ti₅O₁₂ (LTO) were synthesized by the sol-gel method and the solid-state method, respectively. The particle sizes of the products LiNi_0.4Mn_1.5Cr_0.1O₄ and Li₄Ti₅O₁₂ were 0.5 to 2 um and 0.5 to 0.8 um, respectively. All samples exhibited excellent electrochemical properties. A LiNi_0.4Mn_1.5Cr_0.1O₄/Li₄Ti₅O₁₂ (LNMCO/LTO) cell was fabricated and was demonstrated to exhibit good electrochemical properties at the high current rate of 1 C. When the specific capacity was determined based on the mass of the LNMCO cathode, the LNMCO/LTO cell delivered 125 mAh g⁻¹ at 1 C and 77 mAh g⁻¹ at 5 C. The capacity retentions after 30 cycles were 94.4 % and 83.1 %, respectively.