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。     

含Mn复合空心微珠的自反应淬熄法制备与吸波性能研究

采用火焰喷射自反应淬熄技术制备了含Mn铁氧体与氧化铁复合空心微珠,分析了空心微珠的形态、组成和结构,研究了空心微珠的合成机理。获得的空心微珠产物,球化率和空心率较高,但壁厚不均匀,粒径在几十微米范围,排水法测试平均密度为1.58 g/cm3。吸波测试显示,空心微珠与石蜡混合涂层的吸波反射率最小值为–31.4 d B,最佳匹配厚度为4 mm,对应的吸收频率为5.2 GHz,并且随着厚度1~5 mm变化,吸波频段呈现出可调性。     

添加Zn对自反应淬熄法制备Mn-铁氧体空心微珠相结构与性能的影响

采用自反应淬熄法制备了Mn-铁氧体复合空心微珠,分析了自蔓延反应体系中添加Zn元素对制备空心微珠的形貌、相结构和电磁参数的影响。结果表明,制备的粉末大部分为球状空心微珠,粒径在微米范围,少量自蔓延反应不完全的团聚颗粒未能球化,形成不规则颗粒。Zn的引入使得微珠成分转变为以Mn0.5Zn0.5Fe2O4铁氧体为主,提高了Mn-铁氧体复合空心微珠的微波电磁损耗,使吸收峰向高频移动。     

空心微珠表面化学镀Ni-P合金及其吸波性能研究

采用化学镀法在平均粒径2 μm的空心微珠表面包覆了均匀完整的Ni-P非晶合金镀层,并对该材料进行了电磁性能和吸波性能测试.测试结果表明:空心微珠包覆Ni-P非晶合金镀层后矫顽力达到343.08Oe,属于电磁损耗型材料;以包覆后的空心微珠粉体为吸收荆制备吸波涂层,当涂层厚度为3 mm时,在4.32GHz达到最强吸收-20.81 dB,当涂层厚度为1.5 mm时,在8.56～10.08 GHz内出现了小于-10 dB的较宽吸收.     

KNO3对FeSiAl软磁合金空心微珠制备及低频吸波性能的影响

为了获得轻质、低频、高效吸波剂,本文采用自反应淬熄法,分别以Fe+Si+Al、Fe+Si+Al+KNO3为反应体系制备了FeSiAl软磁合金空心微珠,通过SEM、XRD、矢网分析仪等手段研究了KNO3对其密度、形貌、相组成和低频吸波性能的影响。结果表明,未加KNO3时,反应难以进行,淬熄产物由球形颗粒、类球形颗粒、不规则颗粒和片状颗粒组成,物相主要为Fe、Si、Al及部分Fe0.9Si0.1,未生成FeSiAl合金,基本无吸波性能;添加KNO3后,反应体系的淬熄产物主要为空心微珠,粒径分布均匀,物相由Fe3Si0.5Al0.5、Fe3Si0.7Al0.3、Fe0.9Si0.1和Fe组成,获得了FeSiAl合金,在5 mm厚度条件下,吸波试样最低反射率达-22.1 dB,吸收峰值对应频率为7.0 GHz,低于-10 dB的有效吸收频带为5.3-8.5 GHz,带宽达3.2 GHz。KNO3分解反应所产生的高放热量和大量气体是促使反应温度升高、反应产物熔融、目标产物形成、成球率和空心率提高及低频吸波性能显著改善的根本原因。和机械合金化法制备的片状FeSiAl软磁合金相比,自反应淬熄法制备的FeSiAl空心微珠的低频吸波频带有效拓宽,同时材料的密度降低了38 %,有效实现了新型低频吸波料“薄、宽、轻、强”的特点。     

Zn~(2+)含量对纳米Ni_(1-x)Zn_xFe_2O_4粉末在X波段吸波特性的影响

利用溶胶-凝胶自蔓延燃烧反应制备了Ni1-xZnxFe2O4(x=0.5,0.65和0.8)铁氧体纳米粉末,将粉末分别在550、800和1050℃下退火2 h,研究了各退火样品的晶体结构及自燃烧样品在X波段(8.2～12.5 GHz)的电磁性质。XRD分析表明,随Zn2+含量的提高,在自燃烧及550℃退火后,除尖晶石主相外,还有微量的ZnO、Fe3O4杂相;经800℃及其以上较高的温度退火后,所得样品呈完好的尖晶石相。VSM及微波矢量网络测量表明,Zn2+含量影响材料的比饱和磁化强度和矫顽力以及吸波性能、复介电常数和复磁导率;适当的Zn2+含量可提高纳米晶材料的自然共振频率,展宽其吸收频带,提高其复磁导率和磁损耗性能,改善其吸波性能。当x=0.65时,纳米Ni0.35Zn0.65Fe2O4粉末的吸波性能最好。当涂层厚度d=1mm时,其在测试频段内有四个吸收峰,在频率f=11.2315 GHz处,最大吸收值为15.879 dB;在9.0～11.7 GHz,吸收值达8 dB以上,μ'值达1.0以上,μ"值基本在0.7以上;其中吸收值超过11 dB和μ"值超过1.0的带宽达1.2 GHz。     

自反应喷射成形法制备Mn-Zn铁氧体多孔微球研究

以Fe、MnO_2、Fe_2O_3和ZnO为反应体系,采用自反应喷射成形技术制备Mn-Zn铁氧体多孔微球材料,并研究了多孔微球的吸波性能及影响因素。通过SEM、XRD和网络矢量分析仪等设备分析了多孔微球的物相组成、形貌特征、电磁参数和吸波性能。结果表明,微球形状规则,表面粗糙多孔,粒径在100μm,由单一尖晶石型Mn_(0.5)Zn_(0.5)Fe_2O_4相组成。多孔微球的吸波性能良好,在13 GHz附近出现吸收峰,最高峰值达到-16d B;低于-8 d B的频率带宽达到4GHz。微球中多孔的结构特点和锰锌铁氧体的介电损耗是微球吸波的主要原因。Mn-Zn铁氧体多孔微球材料具有良好的吸波性能,值得推广应用。     

离子取代镍基铁氧体的性能及吸波涂层优化设计

在同等实验条件下,以镍铁氧体为基体,通过溶胶-凝胶法,制备二元镍基复合铁氧体Ni0.5A0.5Fe2O4(A=Zn,Co,Mn,Cu)。用X射线衍射仪、扫描电子显微镜、振动样品磁强计和矢量网络分析仪对粉末的结构及电磁性能进行表征并对其吸波性能进行优化设计。结果表明:4种离子取代后均能形成在室温条件下具有超顺磁性的纯净镍基铁氧体粉末。离子取代使铁氧体样品的复介电常数实部ε′增大,虚部ε″在2~6 GHz和13~18 GHz变小,在6~13 GHz增大。Zn2+、Mn2+、Cu2+3种离子取代样品与未进行离子取代的NiFe2O4相比,其复磁导率实部μ′变化不大,而Co2+离子取代样品的μ′整体要大于其他几种离子取代样品及未取代样品的μ′;在2~11 GHz进行Zn2+、Co2+、Mn2+3种离子取代样品的虚部μ″变大,且以Ni0.5Zn0.5Fe2O4的最大,Cu2+取代样品的虚部μ″与未取代样品的虚部μ″相比变化不大。利用传输线理论优化设计时发现,Co2+取代后的复合铁氧体没有匹配点,Zn2+取代后的复合铁氧体匹配效果最好,在最佳匹配厚度为5.63 mm时,其最小反射率峰值为-36.26 dB,小于-10 dB的频宽可达4.7 GHz。     

镍粉/平面六角锶铁氧体复合材料微波吸收性能的研究(英文)

采用溶胶凝胶法制备了平面六角铁氧体,并用扫描电镜(SEM),X射线衍射仪(XRD)对它的形貌以及相结构进行了表征,用矢量网络分析仪(VAZ)研究了不同比例的Ni/铁氧体混合物的微波吸收性能。结果发现,随着混合物中的平面六角铁氧体含量增多,混合物的微波吸波吸收峰向高频方向移动,当混合物由20%Ni+80%铁氧体组成时,混合物的微波吸收性能最佳。当吸波涂层厚度为2 mm时,在12 GHz处,最小反射率为–20 d B,小于–10 d B的带宽达到了4 GHz。当吸波涂层厚度增加时,吸收峰频率向低频移动,吸收峰值先变小,后增大。当厚度达到一定值时,混合物在2~18 GHz之间出现2个吸收峰,这对于研究宽频吸收具有重要意义。     

Microwave Absorbing Properties of Ni/Ferrite Mixture

采用溶胶凝胶法制备了平面六角铁氧体,并用扫描电镜 (SEM),X射线衍射仪 (XRD) 对它的形貌以及相结构进行了表征,用矢量网络分析仪 (VAZ) 研究了不同比例的Ni/铁氧体混合物的微波吸收性能。结果发现,随着混合物中的平面六角铁氧体含量增多,混合物的微波吸波吸收峰向高频方向移动,当混合物由 20%Ni + 80% 铁氧体组成时,混合物的微波吸收性能最佳。当吸波涂层厚度为 2 mm时,在12 GHz 处,最小反射率为–20 dB,小于–10 dB的带宽达到了4 GHz。当吸波涂层厚度增加时,吸收峰频率向低频移动,吸收峰值先变小,后增大。当厚度达到一定值时,混合物在 2~18 GHz 之间出现 2 个吸收峰,这对于研究宽频吸收具有重要意义。     

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.     

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.     

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。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).