一种具有宽频吸波性能的环氧树脂基夹层复合板设计与制备

本文设计和制备了一种在C波段上具有宽频吸波性能的夹层复合材料,并用同轴电缆法和矢量网络分析仪分析了复合材料板的电磁参数和反射率。复合材料板厚度5mm,板表层与底层为玻璃纤维/环氧树脂复合材料,以“Fe50Ni50粉体/丁基橡胶纳米复合材料”为中间夹层。采用液相还原法制备了粒径约为100nm的球形Fe50Ni50粉末,采用二步共混法制备了Fe50Ni50 /IIR复合材料。研究表明, Fe50Ni50粉体/IIR纳米复合材料在2~18GHz频带上以磁损耗为主。表层与夹层的匹配是获得宽频吸波特性的关键,可以通过调整表层与夹层的厚度获得良好的吸波性能。当复合材料板厚度为5mm、夹层厚度为2mm时,板的R≤-10dB的吸波频带为5.6GHz~7.6GHz和16.8GHz~18GHz,吸波带宽达到3.2GHz,该材料在C波段吸波带宽达到2GHz,取得了突破。     

溶剂热法Fe3O4纳米颗粒的制备及表征

以乙醇及水的混和溶剂、单质Fe为原料在高温高压反应釜中制备了Fe3O4纳米颗粒。XRD及红外分析表明所获得产物为Fe3O4。高分辨透射电镜观察表明,Fe3O4具有长棒状形貌,长度为200～500nm,直径为20～30nm。所获得Fe3O4纳米颗粒具有良好的铁磁性能,其饱和磁化强度达到64.75emu/g。讨论了Fe3O4纳米颗粒的形成机制。     

LiZn铁氧体空心微珠的自反应淬熄法制备及其低频吸波性能研究

以Fe+Fe2O3+Li2CO3+Zn O为主反应体系、聚乙二醇为表面活性剂,Bi2O3为助熔剂,KCl O4为营养剂,运用将火焰喷射技术与自蔓延高温合成技术及快速冷却凝固技术相结合的自反应淬熄法,制备了Li Zn铁氧体空心复相微珠。通过粒度分析、SEM、EDS、XRD和矢量网络分析仪等手段,分别分析了该空心微珠的粒径、结构、形貌、相组成和吸波性能。研究表明,该Li Zn铁氧体空心微珠粒径分布均匀,集中在60μm左右,包含实心、单孔和多孔型多种结构,以及部分不规则颗粒。空心微珠外表面出现了晶化程度不高的多边形片状晶,内表面为微纳米晶粒,相组成为Fe3O4、Fe2O3、Li0.435Zn0.195Fe2.37O4和Li0.5Fe2.5O4;该空心微珠吸波材料最佳匹配厚度为4 mm,在此厚度下低频吸波性能良好:最低反射率为-14.5 d B,对应的吸收频率为5.8 GHz,低于-10 d B的吸收频带为4.8~6.8 GHz,带宽达2 GHz。     

碳纳米管/四氧化三铁复合材料的磁性能和电催化性能

采用水热法制备碳纳米管(MWCNT)/四氧化三铁(Fe3O4)复合材料,运用透射电子显微镜(TEM)、X射线衍射(XRD)、傅立叶红外吸收光谱(FTIR)、振动样品磁强计(VSM)以及循环伏安法等对复合材料的微观结构、磁性能以及电化学行为进行研究和分析。结果表明:在MWCNT/Fe3O4复合材料中,磁性Fe3O4纳米颗粒能够对MWCNTs表面较好的包覆,实现了Fe3O4对MWCNTs的表面修饰;Fe3O4含量(质量分数)为62.5%的复合材料容易被磁化,常温下其饱和磁化强度(Ms)为35.89 A·m2/kg,矫顽力(Hc)为0.19 A/m,表现出良好的顺磁性;MWCNTs/Fe3O4修饰玻碳(GC)电极对H2O2的电化学响应具有良好的促进作用,使其氧化还原过电位升高,氧化峰值电流显著增强。     

Zn-Ti钡铁氧体空心陶瓷微珠吸波材料的研究

利用自反应淬熄法制备了Zn-Ti钡铁氧体空心陶瓷微珠吸波材料,这种材料具有核/壳结构,比一般的铁氧体密度小,是一种新型的吸波材料;通过SEM、EDS和XRD分析表明,该材料具有中空结构,成球规则,粒径分布均匀,经过热处理之后,由非晶相物质转变为了晶相物质,主要物相为Ba Zn Ti Fe10O19和Ba Fe12O19;通过吸波性能测试,该材料具有一定的吸波性能,经过热处理之后吸波性能提高了,其吸波最低反射率为–21.98 d B,反射率小于–10 d B的带宽大于2 GH Z。     

超顺磁性还原氧化石墨烯/Fe3O4空心球纳米复合材料的合成、表征及性能研究

本论文采用一种简单有效的静电自组装的方法成功合成出还原氧化石墨烯包覆Fe3O4空心球纳米复合材料（r-GO/Fe3O4）。运用X射线粉末衍射(XRD)、扫描电子显微镜（SEM）、透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)、红外-可见光谱（FT-IR）以及拉曼光谱等手段对合成出的产物进行了系统的表征。r-GO/Fe3O4纳米复合材料表现出优良的超顺磁性,室温下的饱和磁化强度高达70.2 Am2 kg-1,并且在外加磁场下可以快速在水溶液中实现分散和分离。较高的饱和磁化强度和优良的水分散性使得这种新型的r-GO/Fe3O4纳米复合材料在包括磁共振成像、生物传感器、通信以及微波吸收等领域具有一定的应用价值。     

PEI包覆磁性Fe_3O_4纳米颗粒的制备及性能研究

由于PEI/Fe3O4磁流体具有良好的生物兼容性,因而被广泛应用于生物医药领域。本实验用共沉淀法制备出磁性Fe3O4纳米颗粒,通过一次包覆改性法将PEI（聚乙烯亚胺）包覆在磁性Fe3O4纳米颗粒上。利用X-射线衍射仪（XRD）、透射电子显微镜（TEM）、红外光谱仪（FTIR）、振动样品磁强计（VSM）、热重分析仪（TG）等方法对其进行了表征。结果表明,实验制备出颗粒度为10nm左右的颗粒,PEI较好的吸附在其表面,吸附率为33.6%,颗粒度饱和磁化强度为58.05 emu/g,包覆后有所降低,但较好保持着原有磁性。     

介孔纳米磁性材料的性能控制(英文)

以SBA-15介孔分子筛为载体,利用溶胶凝胶-浸渍法合成一种新型纳米结构的磁性材料,同时利用XRD及VSM分析了合成介孔材料的微观结构以及磁性能。结果发现,合成材料的Fe2O3纳米颗粒存在于SBA-15的骨架中,而CoFe2O4纳米颗粒存在于介孔孔道中。介孔纳米磁性材料的磁性能可以通过掺杂CoFe2O4及Fe2O3的含量进行控制。掺杂CoFe2O4样品的饱和磁化强度可达未掺杂样品的12倍。此外,利用Kelly-Hankel(δM)曲线研究了合成介孔纳米磁性材料中CoFe2O4与Fe2O3纳米磁性材料间的交换耦合作用,这可以明显提升合成介孔材料的磁性能。     

多壁碳纳米管/双马来酰亚胺树脂复合材料的制备及其电磁性能

采用化学气相沉积(CVD)法,在1000℃、氮气保护气氛下,制备了铁-钴-镍混合粉末掺杂的多壁碳纳米管(m-MWCNTs,m=Fe-Co-Ni)。再以m-MWCNTs作为吸波剂,双马来酰亚胺(BMI)树脂为基体,制备出m-MWCNTs/BMI复合吸波材料。使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、矢量网络分析仪等对复合材料的微观结构和电磁性能进行表征和测试分析。结果表明,m-MWCNTs作为吸波剂,对电磁波既有介电损耗,也有较强的磁损耗;在2~18 GHz频率范围内,当m-MWCNTs质量分数为8%时,2 mm厚度复合材料的电磁反射损耗在频率为12.96 GHz处达到–12.63d B,频率带宽(低于–5d B)达到5.2 GHz,表明m-MWCNTs/BMI复合吸波材料具有良好的电磁参数匹配特性。     

α-MoO3/CRF复合电极的制备及其在超级电容器中的应用

以(NH4)6Mo7O24·4H2O和HAc为原料, 制备了超级电容器电极活性材料α-MoO3粉末, 并以间苯二酚(R)和甲醛(F)为原料, 碳酸钠(C)为催化剂, 制备了炭气凝胶(CRF). 用X射线衍射仪和扫描电镜对α-MoO3和CRF进行了表征. 研究了不同配比的α-MoO3和炭气凝胶组成的α-MoO3/CRF复合电极的电化学性能. 循环伏安、恒流充放电实验显示了所制备的炭气凝胶以及α-MoO3/CRF复合电极材料具有良好的电化学性能. 炭气凝胶电极的比容量为110.8 F/g, 而当α-MoO3含量在10%时, α-MoO3与炭气凝胶复合制成的新型电极材料的比容量为279.8 F/g, 且所制备成的电容器的比电容可达47.6 F/g.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.