对合成Al_3Ti/ADC12复合材料微观组织与力学性能的影响（英文）

研究了不同含量的改性剂Sr对原位合成Al_3Ti/ADC12复合材料微观组织及力学性能的影响。通过光学显微镜以及扫描电镜观察复合材料的微观以及断口组织。结果表明:Sr的加入能有效减小α-Al以及Al_3Ti颗粒尺寸以及优化材料组织形态。Sr的最优加入量为0.25%(质量分数)。在该加入量条件下,共晶硅由针状或短棒状变为颗粒状,α-A1粗枝晶得到较好的细化,抗拉强度以及延伸率相对基体材料增加了36.9%和58%。断口形貌表明,在最优加入量条件下所制备的复合材料断口几乎看不到解理面和脆性平坦区,韧窝数量增多,韧窝尺寸变得更小且深,同时分布也较为均匀。断口形貌的特征与材料力学性能变化相一致。     

超声辅助激光沉积原位TiC-TiB2/Al-12Si铝基复合材料微观组织及摩擦磨损行为研究

以Ti、B₄C和Al-12Si粉末为原材料,通过超声辅助激光沉积制备了原位TiC-TiB₂/Al-12Si铝基复合材料。采用XRD、EDS分析了复合材料的物相组成,通过OM、SEM观察了复合材料的微观组织,利用摩擦磨损试验机和三维轮廓仪测试了复合材料的磨损性能。结果表明,随Ti+B₄C含量的增加,ɑ-Al晶粒细化,原位生成的TiB₂呈棒状,且可成为ɑ-Al的异质形核核心;原位生成的TiC为150nm多边形形貌。随Ti+B₄C含量的增加,原位TiC-TiB₂/Al-12Si铝基复合材料的耐磨性提高;未加入Ti+B₄C的Al-12Si合金磨损机制为粘着磨损;当Ti+B₄C的加入量为8wt.%时,磨损机制为磨粒磨损;当Ti+B₄C的加入量为10wt.%时,其磨损机制转变为粘着磨损。     

预热温度对三维五向Cf/Al复合材料微观组织及室温与高温力学性能的影响

以石墨纤维三维五向织物为增强体,铝合金ZL301为基体材料,采用真空辅助压力浸渗法制备了三维五向增强C_f/Al复合材料,研究了不同温度制备的复合材料微观组织特征和界面反应程度,测试了复合材料在室温和高温下的拉伸力学性能并分析了其断口形貌。结果表明：复合材料相对致密度随制备温度提高而增加,纤维局部偏聚现象也明显减少,与此同时,界面反应物Al₄C₃相随制备温度提高而显著增多,530℃到570℃复合材料室温拉伸极限强度随组织缺陷减少而增加,570℃到600℃复合材料室温极限拉伸强度随界面反应程度增大而显著降低;高温拉伸极限强度随制备温度提高而增加,适当提高界面反应程度有利于提高复合材料高温力学性能,高温拉伸中基体合金回复软化和界面结合强度弱化促进了复合材料断裂过程中的纤维拔出与界面滑移。     

原位颗粒对近液相线铸造6063铝合金微观组织和耐磨性的影响机理

以CuO-Al作为反应体系,在6063铝合金中原位反应生成Al₂O₃颗粒,采用近液线相铸造的方法制备6063Al-XAl₂O₃(X=0,2,4,6)复合材料。研究原位反应颗粒Al₂O₃与6063铝合金自带的原位结晶颗粒Mg₂Si的形状、尺寸、数量、分布、界面特征等对合金微观组织和耐磨性的影响机理。结果表明,在6063铝合金中原位反应生成尺寸在亚微米级的近球形θ-Al₂O₃颗粒;其(311)晶面与6063铝合金基体(111)晶面成共格界面;6063铝合金中Mg₂Si尺寸大约为100nm,呈条带状,其(02-2)与Al基体(111)晶面属于共格界面。随着Al₂O₃颗粒含量的增加,6063铝基复合材料的晶粒组织形貌由蔷薇状逐渐向等轴晶转变,晶粒尺寸逐渐减小。当Al₂O₃的质量分数为6%时,复合材料组织由等轴晶和细小的柱状晶组成。载荷为50N时,6063铝合金的磨损量为6.72mg,6063-6Al₂O₃复合材料的磨损量为1.63mg,相对于6063铝合金降低75.7%。原位颗粒(Al₂O₃+Mg₂Si)与铝基体都成共格界面,界面之间无污染,界面结合强度高,在磨损过程中,不易从基体中脱落,承当磨损过程中的大部分载荷。原位生成高硬度的Al₂O₃颗粒与原位结晶颗粒Mg₂Si协同作用共同提高复合材料的耐磨性。外加载荷为40N时,随着增强相质量分数的增加,复合材料的磨损机制由粘着磨损转变为磨粒磨损。6063铝合金磨损机制以严重的粘着磨损为主。6063-2Al₂O₃复合材料磨损机制主要以粘着磨损为主,6063-4 Al₂O₃和6063-6Al₂O₃复合材料主要表现为磨粒磨损。     

载体中ZrO2/Al2O3比对Pt/ZrO2-Al2O3催化剂性能的影响

相比汽油车而言,柴油车具有高效、低油耗的优势已得到广泛应用。本实验以ZrO₂作为改性剂,探究了ZrO₂与Al₂O₃的质量比对催化剂的影响。研究结果表明：随着ZrO₂的加入,Pt粒子先减小后增大;Pt粒子与载体的交互作用先增大后减小。活性实验数据分析表明,ZrO₂的最佳添加量为40 wt%,CO和C₃H₆完全氧化温度分别降低20 _oC 、25 _oC。贵金属在催化剂的分散度以及贵金属与载体的相互作用随着ZrO₂与Al₂O₃质量比的变化而变化。Pt粒子越小,其与载体的交互作用越强,这表明催化剂性能越强。     

La2O3含量对搅拌摩擦加工制备Ni /Al复合材料组织和性能的影响

采用搅拌摩擦加工方法在Al基体中添加不同La₂O₃含量的混合粉末(Ni+La₂O₃),制备 (Ni+La₂O₃)/Al复合材料。采用SEM、EDS、 EPMA及XRD对复合区微观结构及相组成进行分析,采用室温拉伸试验对 (Ni+La₂O₃)/Al复合材料力学性能进行了测试。结果表明,随着La₂O₃含量的增加,(Ni+La₂O₃)/Al复合材料的组织和性能先变好后变差。当La₂O₃添加量达到5%时,复合材料中Al₃Ni增强颗粒分布均匀、颗粒数量最多,块状的Ni粉团聚减少,其抗拉强度达到最大值215MPa,相比Ni/Al复合材料(抗拉强度176MPa),其抗拉强度提高了22%;当La₂O₃的添加量为7%时,复合材料中Al₃Ni增强颗粒含量减少,块状Ni粉团聚重新出现,抗拉强度下降至201MPa。     

高阻尼高强度铸态SiCp/Mg94Zn5Y1 复合材料的综合性能

采用铸造方法制备具有不同SiC_p含量（0.5%~2.0%，质量分数，下同）的SiC_p/Mg₉₄Zn₅Y₁复合材料，并研究了复合材料的力学性能和阻尼性能。通过扫描电子显微镜和X射线衍射仪测试复合材料的微观组织结构和物相组成。在基体中加入SiC_p之后，SiC_p均匀分布在基体中，增强体细化了复合材料的微观组织结构。SiC_p/Mg₉₄Zn₅Y₁复合材料包括α-Mg、I相（准晶相）和SiC_p相。分别使用动态热机械分析仪和AG-X试验机测试了SiC_p/Mg₉₄Zn₅Y₁复合材料的阻尼性能和力学性能。复合材料的力学性能优于Mg₉₄Zn₅Y₁合金，1.0%SiC_p/Mg₉₄Zn₅Y₁复合材料的抗压缩强度高达350 MPa；所有复合材料的阻尼性能都远高于基体合金的阻尼性能，其中0.5%SiC_p/Mg₉₄Zn₅Y₁复合材料具有最佳的阻尼性能。此外，根据功效系数法，SiC_p含量为1.0%的SiC_p/Mg₉₄Zn₅Y₁复合材料具有良好的综合性能。     

高压凝固Al2O3/Al-10Si复合材料组织热稳定性及力学性能研究

本文采用高压凝固的方法分别在3、4、5 GPa的压力下制备了Al₂O₃/Al-10Si复合材料,并分别在160 ℃保温2、4、6 h的条件下研究了高压凝固Al₂O₃/Al-10Si复合材料的组织热稳定性以及力学性能转变规律。研究表明：热处理导致高压凝固Al₂O₃/Al-10Si复合材料α相固溶的Si在热激活的作用下脱溶析出,聚集长大形成细小颗粒弥散分布于α相内,形成沉淀强化；160 ℃热处理后α相固溶的Si析出,过饱和程度下降,材料性能逐渐趋于稳定,在沉淀强化的共同作用下,Al₂O₃/Al-10Si复合材料抗压强度和压缩率较热处理前均有所上升。而160℃保温4 h的条件下,材料的综合力学性能最好。尤其在5 GPa压力下凝固的Al₂O₃/Al-10Si复合材料,抗压强度可达到716 MPa。     

SnO2 增强相对AgCuOIn2O3 电触头材料显微组织与性能的影响

采用反应合成法结合塑性变形工艺制备了不同SnO₂含量的AgCuOIn₂O₃SnO₂电触头材料,利用扫描电镜和金相显微镜表征了材料的微观形貌及显微组织,分析对比了不同SnO₂含量的材料金相组织及其增强相的分布均匀性,并利用X射线衍射分析了材料的物相结构。测量了材料的抗拉伸强度、硬度、电阻等性能。结果表明：添加适量的SnO₂能使组织中的孔隙尺寸缩小、其他缺陷明显减少。氧化物弥散分布在银基体中,极大地改善了AgCuOIn₂O₃电触头材料的显微组织均匀性。在SnO₂含量不变时,材料的电阻率随塑性变形程度增加而有所降低;随着SnO₂含量增多,电阻率呈现先降低后升高的趋势,最后趋于定值,约为2.4 μΩ·cm。添加SnO₂后各试样材料的硬度均显著升高,SnO₂含量为1%（质量分数）的材料具有最优的抗拉伸强度和延伸率。     

Al2O3微粉添加量对镁合金微弧氧化膜特性影响研究

为了研究添加Al₂O₃微粉对AZ31A镁合金微弧氧化膜特性影响,在不同浓度Al₂O₃微粉电解液中对其进行了微弧氧化处理。利用扫描电镜(SEM)观察微弧氧化膜形貌,能谱仪(EDS)分析了膜层表面Ca、Mg、O、Al元素分布,X射线衍射仪(XRD)分析了相组成,测定了膜厚、硬度和氧化液中Al₂O₃表面电荷,讨论了掺杂改性机理。结果表明,加入Al₂O₃微粉后,氧化电压随Al₂O₃添加量增加先增加后降低;氧化膜表面孔洞数量和尺寸减小,膜层表面Ca元素分布逐渐减少,成膜效率降低,膜层致密度和表面疏松层硬度提高,氧化膜主要由MgO和MgO₄等相组成。     

废旧锂离子电池中Li, Fe和V的回收及xLiFePO4-yLi3V2(PO4)3的制备

由于LiFePO_4和Li_3V_2(PO_4)_3材料的特征相近,制备方法类似,提供了一种从废旧LiFePO_4和Li_3V_2(PO_4)_3混合电池中回收Li、Fe和V,再制备xLiFePO_4-yLi_3V_2(PO_4)_3的方法。在空气气氛中600℃热处理1h后,去除粘结剂PVDF使活性物质与集流体分离。调节Li、Fe、V和P摩尔比,球磨、锻烧,配制不同比例的xLiFePO_4-yLi_3V_2(PO_4)_3(x:y=5:1,7:1,9:1)复合电极材料。表征了其形貌、结构和电化学性能,结果表明,回收制备的复合材料将同时具备LiFePO_4和Li_3V_2(PO_4)_3两种材料的电化学性能,能显著改善LiFePO_4的倍率性能。     

Synthesis of lanthanum carbonate nanoparticles via sonochemical method for preparation of lanthanum hydroxide and lanthanum oxide nanoparticles

Lanthanum carbonate nanoparticles were synthesized from the reaction of lanthanum acetate and Na₂CO₃ under sonication via sonochemical method. Lanthanum hydroxide nanoparticles were prepared by facial hydrothermal processing from the resulted product at 110 °C for 24 h. The role of surfactant, calcination temperature and sonication time were investigated on the morphology and particle size of the products. Products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), and Fourier transform infrared (FT-IR) spectra. La₂O₃ nanoparticles were obtained by calcinations of the nanoparticles of lanthanum carbonate at 600 °C.     

LaSrCuO4粉体微结构对Ag/LSCO电接触材料性能的影响

以硝酸镧、硝酸铜、硝酸锶等为原料,分别采用固相法、溶胶-凝胶法和共沉淀法合成了不规则颗粒状(LSCO_g)、介孔状(LSCOm)和片层状(LSCOl)的LaSrCuO_4(LSCO)粉体。采用高能球磨并结合初压-初烧-热压工艺制备出Ag/LSCO电接触材料。利用X射线衍射(XRD)、扫描电镜(SEM)、金属电导率仪、维氏硬度计和电寿命试验机等对粉体形貌及电接触材料的物理和电学性能进行了表征。结果表明:与Ag/LSCO_(m)、Ag/LSCO_l材料相比,Ag/LSCO_(g)电接触材料表现出更加优异的物理性能,其电阻率为2.37μΩ·cm,硬度为800MPa,密度为9.32g/cm~3;但电学性能差异较小,其在AC220V12A开断状态下的燃弧能量为400 mJ、燃弧时间为23 ms,关合状态下的燃弧能量为1500 mJ,燃弧时间为68ms。Ag/LSCO电接触材料的主要失效形式是液滴喷溅,微裂纹和孔洞。     

Effects of Mo and Al Additions on the Sulfidation Behavior of 310 Stainless Steel

The high-temperature sulfidation behavior of 310stainless steel (310SS) with Mo and Al additions (up to10 at.%) was studied over the temperature range700-900°C in pure-sulfur vapor over the range of 10^-3 to 10^-1 atm. Thecorrosion kinetics followed the parabolic rate law inall cases and the sulfidation rates increased withincreasing temperature and sulfur pressure. Thesulfidation rates decreased with increasing Mo and Al contents and it wasfound that the addition of 10 at.% Mo resulted in themost pronounced reduction among the alloys studied. Thescales formed on 310SS with Mo additions were complex, consisting of an outer layer of ironsulfide (with dissolved Cr), (Fe,Ni)₉S₈, andCr₂S₃/Cr₃S₄(with dissolved Fe), and an inner heterophasic layer ofFe_1-xS,Cr₂S₃/Cr₃S₄,NiCr₂S₄,Fe_1.25Mo₆S_7.7, FeMo₂S₄, andMoS₂. The scales formed on 310SS with Mo andAl additions had a similar mixture as above, except thatAl_0.55Mo₂S₄ was alsoobserved in the inner layer. The formation ofMoS₂ andAl_0.55Mo₂S₄ partly blocked the transport of cations throughthe inner scale, resulting in the reduction of thesulfidation rates compared to 310SS.     

Effects of sulfur pressure on the sulfidation behavior of 310 stainless steel

High-temperature sulfidation behavior of 310 stainless steel was studied over the temperature range of 700–900°C above a pure sulfur pool with the sulfurvapor range of 10^–4–10^–1 atm. The corrosion kinetics followed the parabolic rate law in all cases. The corrosion rates increased with increasing temperature and sulfur pressure. The scales formed on 310 stainless steel were complex and multilayered. The outer scale consisted of iron sulfide (with dissolved Cr), (Fe, Ni)₉S₈ and chromium sulfides (Cr₂S₃ and Cr₃S₄ with dissolved Fe), while the inner layer was a heterophasic mixture of Cr₂S₃, Cr₃S₄, NiCr₂S₄, and Fe₁–_xS. Platinum markers were found to be located at the interface between the inner and outer scales, suggesting that the outer scale grew by the outward transport of cations (Fe, Ni, and Cr), and the inner scale grew by the inward transport of sulfur. The formation of Cr₂S₃, Cr₃S₄, and NiCr₂S₄ partly blocked the transport of iron through the inner scale, resulting in a reduction of the corrosion rates as compared with the results in the literature.     

The high-temperature corrosion behavior of Co-Nb alloys in mixed-gas atmospheres

The corrosion of Co-Nb alloys containing up to 30 wt.% Nb in H₂-H₂S-H₂O gas mixtures was studied over the temperature range of 600–800°C. The gas composition falls in the stability region of cobalt sulfide and Nb₂O₅ in the phase diagrams of the Co-O-S and Nb-O-S systems at all temperatures studied. Duplex scales, consisting of an outer layer of cobalt sulfide and a complex, heterophasic inner layer, were formed at all temperatures studied. In addition to cobalt sulfide and CoNb₃S₆, a small amount of NbO₂ was found in the inner layer. The reason for the formation of NbO₂ over that of Nb₂O₅ in the scale is that the outer sulfide scale lowers the oxygen activity within the scale into the NbO₂-stability region. Two-stage kinetics were observed for all alloys, including an initial irregular stage usually followed by a steady-state parabolic stage. The steady-state parabolic rate constants decreased with increasing amounts of Nb, except for Co-20Nb corroded at 700°C. Nearly identical kinetics were observed for Co-20Nb corroded at 600°C and 700°C. The presence of NbO₂ particles leads only to a limited decrease of the available cross-section area for the outward-diffusing metal ions. The activation energies for all alloys are similar and are in agreement with those obtained in a study of the sulfidation of the same alloys. The primary corrosion mechanism involves an outward Co transport.     

Effects of K2O-Li2O doping on surface and catalytic properties of Fe2O3/Cr2O3 system

The effects of K₂O and Li₂O-doping (0.5, 0.75 and 1.5 mol%) of Fe₂O₃/Cr₂O₃ system on its surface and the catalytic properties were investigated. Pure and differently doped solids were calcined in air at 400-600 °C. The formula of the un-doped calcined solid was 0.85Fe₂O₃:0.15Cr₂O₃. The techniques employed were TGA, DTA, XRD, N₂ adsorption at −196 °C and catalytic oxidation of CO oxidation by O₂ at 200-300 °C. The results revealed that DTA curves of pure mixed solids consisted of one endothermic peak and two exothermic peaks. Pure and doped mixed solids calcined at 400 °C are amorphous in nature and turned to α-Fe₂O₃ upon heating at 500 and 600 °C. K₂O and Li₂O doping conducted at 500 or 600 °C modified the degree of crystallinity and crystallite size of all phases present which consisted of a mixture of nanocrystalline α- and γ-Fe₂O₃ together with K₂FeO₄ and LiFe₅O₈ phases. However, the heavily Li₂O-doped sample consisted only of LiFe₅O₈ phase. The specific surface area of the system investigated decreased to an extent proportional to the amount of K₂O and Li₂O added. On the other hand, the catalytic activity was found to increase by increasing the amount of K₂O and Li₂O added. The maximum increase in the catalytic activity, expressed as the reaction rate constant (k) measured at 200 °C, attained 30.8% and 26.5% for K₂O and Li₂O doping, respectively. The doping process did not modify the activation energy of the catalyzed reaction but rather increased the concentration of the active sites without changing their energetic nature.     

Effect of Y2O3 additions on the plasticity of sintered Cr2O3

We have carried our constant strain-rate compression tests on polycrystalline Cr₂O₃ and Cr₂O₃ doped with 0.09 wt. % Y₂O₃ to establish whether there exists an effect of Y₂O₃ on the plasticity of Cr₂O₃. This study is motivated by previous work on the oxidation of alloys containing reactive-element additions. In that work, it has been observed that the addition of oxygen-active elements, such as Y to alloys that form Cr₂O₃ or Al₂O₃ oxide layers upon exposure at high temperature, strongly enhances the adhesion of the oxide layer to the base alloy as compared with alloys without reactive-element additions. We have found that at 1200°C (1) chromia exhibits limited plasticity at high temperatures, and (2) the presence of Y in the oxides does not enhance plasticity compared with addition-free oxides.     

改进型镁扩散法制备高临界电流密度MgB2超导体性能研究

本文采用一种改进型镁扩散法成功制备出密度达到1.95g/cm₃的MgB₂超导块材。论文研究了不同的热处理条件对MgB₂块材的超导转变温度(T_c)和临界电流密度(J_c)性能的影响。采用最佳热处理条件制备的MgB₂超导体T_c和J_c分别达到了38.1K和0.53MA/cm₂(10K,自场)。为了改进镁扩散法MgB₂超导体中弱的高场磁通钉扎性能,本文还研究了nano-Pr₆O₁₁和C掺杂对MgB₂超导体的临界电流密度和不可逆场(H_irr)的影响。结果表明C掺杂的MgB₂超导体临界电流密度在10K,6T下达到了10₄A/cm₂,该结果比未掺杂MgB₂超导体在同样条件下性能提高了两个量级,甚至比固态反应法制备的nano-C掺杂MgB₂超导体性能更好。利用该方法制备的nano-Pr₆O₁₁掺杂的MgB₂超导体在10K,2T下也比未掺杂样品J_c提高达9.4倍。根据大量的实验结果和理论分析我们提出基于改进型镁扩散法和化学掺杂,包括纳米粒子和C掺杂,很有可能是一种制备高性能MgB₂超导体非常有效的途径。     

High-temperature corrosion of Co-15Mo alloys containing ternary additions of Al in mixed-gas environments

The corrosion behavior of Co-15 at.% Mo alloys containing up to 20at.% Al in gaseous H ₂ -H ₂ O-H ₂ S mixtures was studied over the temperature range of 600–900°C. The corrosion kinetics of all alloys followed the parabolic rate law over the temperature range of interest. Corrosion resistance increased with increasing aluminum content. Complex scales formed on the alloys, consisting of an outer layer of cobalt sulfide and a heterophasic inner layer. Al ₂ O ₃ formed only at high temperatures in alloys having aluminum additions of 15at.% or more. The absence of Al ₂ O ₃ in some cases is due to the small volume fraction of the intermetallic phase CoAl in the alloys and the nature of the slow growth rate of Al ₂ O ₃.Improvement in corrosion resistance is attributed to the presence of a ternary sulfide, Al _0.55 Mo ₂ S ₄,and Al ₂ O ₃ in the inner layer.