Microwave magnetic properties of laminates with thin FeCoBSi films

The microwave permeability of laminated composites based on thin FeCoBSi films was under study.The level of permeability increased with increasing of the ferromagnetic inclusions in the laminates.The intrinsic permeability spectra of ferromagnetic inclusion are parametrically reconstructed.The obtained parameters of magnetic resonance were specially analyzed.To avoid the effect of eddy current and to obtain large-volume fractions of ferromagnetic constituent,laminates consisting of alternating FeCoBSi/SiO2 multi-layers and mylar substrates were also investigated.For the same volume fractions of ferromagnetic constituent (8.7%),laminates based on multi-layered films are found to possess higher values of permeability than those based on one-layered films.     

Property of three-dimensional silica composites

Silica fibers-reinforced, fused silica composites were fabricated with repeated vacuum-assisted liquid-phase infiltration. The mechanical properties, thermal properties, and ablative properties of the samples were evaluated. The effect of the silica fiber content and treatment temperature on the flexural strength of the three-dimensional SiO2 （3-D SiO2） composites also was investigated. The SiO2 composites show good mechanical properties and excellent ablative performance. The flexural strength increases with an increase in silica fiber content, and decreases with an increase in treatment temperature. When the volume fraction of the silica fiber is 50vo1% and the treatment temperature is 700℃ the flexural strength of the composites reaches a maximum value of 78 MPa. By adding cyclohexanone surfactant, the infiltration property can be largely improved, resulting in the density of SiO2 composites increasing up to 1.65 g/cm^3. The fracture surfaces of the flexural specimens observed using SEM, show that the pseudoplasticity and the toughening mechanisms of the composites are caused by absorption of a lot of energy by interface debonding and fiber pulling out.     

纳米碳纤维掺杂量与取向对纳米碳纤维/乙烯-醋酸乙烯酯复合材料介电性能的影响

通过微波法化学镀镍对纳米碳纤维(CNFs)进行表面改性,采用熔融共混法将表面改性的CNFs与乙烯-醋酸乙烯酯(EVA)复合制备CNFs/EVA复合材料,在模压交联过程中对复合材料施加磁场,使表面镀镍的CNFs在复合材料基体中沿磁场方向取向;用场发射扫描电子显微镜(FE-SEM),透射电子显微镜(TEM)和X射线衍射仪(XRD)观察表面改性前后CNFs表面形貌和结构、复合材料内部微观结构及取向情况;用宽频介电谱仪与阻抗谱仪对复合材料进行介电谱测试,研究了CNFs的取向与掺杂量对复合材料介电性能的影响,并用四探针法测量复合材料的体电阻率。研究结果表明,掺杂量和是否取向对复合材料介电性能影响较大;CNFs掺杂质量分数为0.5%时,取向复合材料相对介电常数最低,施加磁场取向不会增加复合材料的介电损耗,少量掺杂即可大幅降低复合材料的体电阻率。     

纳米颗粒弥散强化铜基复合材料的显微组织与性能

采用粉末冶金的方法,以Al2O3,SiO2,SiC和MgO等纳米颗粒为增强相,制备出4种不同颗粒的纳米复合材料,研究了各增强相对复合材料显微组织与性能的影响.结果表明:在相同的质量分数(ω)和制备工艺下,不同弥散相颗粒的弥散强化铜合金显微组织不同,铜基体上大体均匀地分布着细小的弥散相颗粒,但部分区域仍存在偏聚现象.4种复合材料的电导率相近,抗拉强度方面Cu/Al2O3与Cu/SiO2的性能要略好于Cu/SiC与Cu/MgO.     

The multiscale modeling and data mining of high-temperature dielectrics of SiO2/SiO2 composites

Quartz fibre-reinforced silicon dioxide ceramic(SiO2/ SiO2) composites have long been the primaryceramic material used for hypersonic missile radomes,owing to its outstanding thermal shock resistance, lowand stable dielectric properties and its ease of fa…     

纳米SiO2填充尼龙PA1010的摩擦磨损性能实验研究

用纳米 Si O2 填充 PA1 0 1 0制备了尼龙复合材料 ,并用 MM- 2 0 0磨损试验机对尼龙复合材料与 45钢在干摩擦条件下的摩擦磨损实验进行了实验 .研究表明 ,纳米 Si O2 填充 PA1 0 1 0大幅度提高了尼龙复合材料的耐磨性 ,降低了摩擦系数 .纳米 Si O2 填充量在 1 0 %左右时 ,尼龙复合材料达到最低摩擦系数 0 .32和最低磨损量 0 .2 mg,磨损量比纯 PA1 0 1 0降低了 60多倍 ,摩擦系数降低了 1倍 .对纳米 Si O2 填充尼龙的磨损机理研究发现 ,纳米 Si O2 填充尼龙复合材料的磨损机理受滑动速度和接触载荷影响比较大 .当摩擦副 PV值小于 60 Nm/ s时 ,尼龙复合材料的磨损机理主要是切削和粘着磨损 .当摩擦副 PV值大于 60 Nm/ s时 ,磨损机理转变为疲劳剥层或熔融流变 ,导致磨损量急剧增长 .     

纳米复合材料Ag-H6P2W18O62/TiO2的制备与微波辅助光催化甲基橙

采用溶胶一凝胶再结合程序升温溶剂热一步法制备了纳米复合光催化材料Ag-HeP2WtsOJTiO2,并采用傅立叶一红外光谱（FT-IR）、等离子原子反射光谱（ICP-AES）、氮气吸附一脱附测定和透射电子显微镜（TEM）等测试方法Ag-H6P2W18O62/TiO2合成材料的物理化学性质进行了表征。结果表明,复合材料中母体多酸的基本结构未发生明显变化,其Agl）J单质形式存在,且显示为介孔材料。在微波场作用下,复合材料Ag-H6P2W18O62/TiO2对甲基橙的降解表现了较高的催化活性。     

Microstructures and magnetic properties of [SiO2/FePt]5/Ag thin films

[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.     

聚甲基丙烯酸甲酯／纳米SiO2复合材料研究

目的分析纳米SiO2对聚甲基丙烯酸甲酯／纳米SiO2复合材料基体的各方面性能的影响．方法采用在位分散聚合方法制备聚甲基丙烯酸甲酯／纳米SiO2复合材料,利用硅烷偶联剂KH-570对纳米颗粒表面进行改性,比较改性前和改性后的纳米SiO2及物理方法和化学方法改性的纳米SiO2对复合材料抗折性能、耐热性、耐溶剂性能的影响,并利用扫描电镜拍摄断面照片,观测基体内纳米颗粒的分散形态与材料断面．结果经KH-570表面改性后的纳米材料在基体中分散均匀,复合材料的力学强度虽没有明显提高,但将其玻璃化温度提高了10℃,耐溶剂性也较聚甲基丙烯酸甲酯有明显改善;物理方法处理纳米颗粒表面改性效果更加突出．结论表面改性后的纳米SiO2对聚甲基丙烯酸甲酯的耐热性、耐溶剂性能有明显改善,利用物理方法对纳米颗粒表面改性更适用于工程应用．     

原位聚合纳米SiO2／PMMA的制备与耐磨损性

考察了纳米SiO2／PMMA复合体系的耐磨损性．采用原位本体聚合方法制备．纳米SiO2／PMMA复合板,使用扫描电镜和光学显微镜对纳米SiO2及其复合物进行观察,采用砝码质量法测试复合物的耐磨损性．电镜观察结果表明：纳米SiO2较为均匀地分散在PMMA基体中,并被PMMA所包覆,包覆物的粒径介于30～100nm之间．耐磨损性测试结果表明：纳米SiO2的加入可提高PMMA复合物的耐磨损性和耐划痕性;当纳米SiO2用量为1．0％时,复合物的耐磨损性能提升39．7％．     

双马型聚酰亚胺／SiO_2杂化材料的合成

本文主要应用Ｓｏｌ－Ｇｅｌ法合成了双马型聚酰亚胺／ＳｉＯ２的分子杂化材料。应用ＦＴＩＲ、ＳＥＭ及热分析对杂化材料的机理、结构及热性能进行了表征，这为新材料的研究奠定了一定的理论基础。     

原位自生成陶瓷相增强铝基复合材料的研究

采用粉末冶金法成功制备了原位生成陶瓷相增强AI基复合材料。应用X射线衍射仪进行了物相组成测试,发现含10％－20％（重量百分比） SiO2复合材料的最终物相均为MgAI2O4、MgO、Mg2Si、Si和AI。研究了SiO2含量对复合材料硬度、密度、电导率、抗压强度、磨擦磨损等性能的影响表明,随SiO2含量的增加,复合材料的硬度和密度增加,电导率、抗压强度和体积磨损量减小,而磨擦系数却增加。     

PU杂化膜性能及微孔结构的分形研究

采用湿法相转化法制备了PU／SiO2杂化膜，用扫描电子显微镜进行观察，并依其断面电镜照片进行分形研究．结果显示：SiO2的加入，可改善PU杂化膜的微孔结构，在PU／SiO2杂化体系中添加界面改性剂，可促进SiO2在基体的分散，起到细化微孔的作用．这一性能与分形研究中维数的提高相一致，因此分形理论可以用于将膜孔的结构形态量化．     

Effects of hydrothermal temperatures on properties of magnetic titanate nanotubes

NiFe2O4 dopeded with magnetic titanate nanotubes(MTNT)were prepared by a hydrothermal method using magnetic nanoparticles TiO2/SiO2/NiFe2O4 as the precursor.The effects of hydrothermal temperatures on their composition,morphologies and magnetic properties of products were characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(XRD),vibration sample magnetometer(VSM)and energy dispersive X-ray spectroscopy(EDS).The results show that the hydrothermal temperature has a significant impact on the morphology of the products.The MTNT is synthesized in the temperature range of 120-160 ℃ and the inner diameter of MTNT is about 3-10 nm,the wall thickness 4-12nm and the length 100-200 nm.The components of MTNT are Na0.8H1.2Ti3O7 and a little of anatase TiO2 and NiFe2O4.The ferrimagnetisms and magnetic hysteresis phenomena are shown in the prepared MTNT.The hydrothermal temperature has no clear effect on the magnetic properties in the range of 120-180 ℃.The visible-light photo-catalytic activity of the products decreases as the temperature increases.The decolorization of methylene blue is 94.6% by the MTNT obtained at 120 ℃ and the recovery rate of MTNT is more than 95 percent.The MTNT has excellent photocatalytic activity and is easy to recovery.     

利用粉煤灰制取磷酸盐微孔材料的研究

通过物理和化学方法制孔,控制工艺条件使粉煤灰中的Al_2O_3、SiO_2在高温下和磷酸反应生成聚合AlPO_4与Si0_2·P_2O_5而得到的磷酸盐微孔材料,具有较好的力学性能;本文通过正交实验方法探讨了影响材料力学性能的四个工艺因素。     

Structure and Oxidation Behavior of a Plasma Sprayed Yttrium Silicates Coated SiC-C/C with a Glass Outer Sealant from 1 573K to 1 873K

Different compositions of yttrium silicates coatings were deposited on SiC-C/C by plasma spraying and an outer borosilicate glass was applied on the yttrium silicates coatings surfaces.The structure of the multi-layer coatings was characterized by XRD and SEM analyses.High temperature oxidation behavior of the multi-layer coatings coated C/C composites was investigated.Results show that SiC/2SiO_2Y_2O_3/I.5SiO_2 Y_2O_3/SiO_2 Y_2O_3/glass multi-layer coating has better high temperature oxidation resistance,protecting carbon/ carbon composites from oxidation at 1 773 K in air for 164 h with the weight loss of 1.65%.The oxidation weight loss of the coated C/C with time accorded with parabolic rule in the temperature range 1 573 K-1 873 K; and the corresponding oxidation activation energy of the coated carbon/carbon composites is 132.2 kJ/mol.     

Structure and oxidation behavior of a plasma sprayed yttrium silicates coated SiC-C/C with a glass outer sealant from 1 573K to 1 873K

Different compositions of yttrium silicates coatings were deposited on SiC-C/C by plasma spraying and an outer borosilicate glass was applied on the yttrium silicates coatings surfaces. The structure of the multi-layer coatings was characterized by XRD and SEM analyses. High temperature oxidation behavior of the multi-layer coatings coated C/C composites was investigated. Results show that SiC/2SiO2 Y2O3/1.5SiO2 Y203/ SiO2 Y2O3/glass multi-layer coating has better high temperature oxidation resistance, protecting carbon/ carbon composites from oxidation at 1 773 K in air for 164 h with the weight loss of 1.65%. The oxidation weight loss of the coated C/C with time accorded with parabolic rule in the temperature range 1 573 K-1 873 K; and the corresponding oxidation activation energy of the coated carbon/carbon composites is 132.2 kJ/mol.     

SiO2/Al-Mg复合材料的界面反应

对粉末冶金法制备的SiO2/Al-Mg复合材料的显微组织、物相组成及反应过程进行了研究,发现10%~20%SiO2-Al-Mg复合材料的最终物相均为MgAl2O4、MgO、Mg2Si、Si和Al.反应时Al、Mg由SiO2颗粒外向颗粒内扩散,SiO2被夺去氧,Si被置换到原SiO2颗粒外.总结了颗粒SiO2与Al-Mg反应的热力学,推测了颗粒内外的优先反应.     

氧化石墨烯包覆磁性纳米粒子复合材料的制备及其对亚甲基蓝的模拟吸附

制备了一种氧化石墨烯包覆磁性纳米粒子复合材料,并运用X射线衍射、扫描/透射电镜、傅里叶红外光谱、振动样品磁强计对该复合材料进行了表征。研究结果表明,该复合材料具有Fe3O4核、氧化石墨烯壳的核壳结构,复合材料中皱纹丝状的氧化石墨烯紧密和磁性纳米粒子相连,Fe3O4成单晶状。该复合材料的制备首先在球形的Fe3O4纳米粒子表面包覆SiO2涂层,再在涂层表面赋予-NH2基,最后和氧化石墨烯反应,最终得到具有核壳结构的复合材料。对复合材料的吸附性能进行了初步模拟测试,以亚甲基蓝为吸附质,对溶液pH值、吸附剂量对吸附量的影响以及吸附等温线进行了研究,结果表明该复合材料能够在吸附后在外加磁场下快速分离,是一种优异的吸附剂。     

Microstructure and dielectric properties of BaTi4O9(f)/0.64 BaTi4O9+0.36 BaPr2Ti4O12 composites

The microstructure, dielectric properties and chemical state of Ti element on BaTi4O9 (f)/(0. 64 BaTi4O9-0. 36BaPr2Ti4O12 ) composites sample surface were characterized by X-ray diffraction (XRD) ,Transmission electron microscopy (TEM), LCR meter method and X-ray photoelectron spectroscopy (XPS).The results show that the system is composed of BaTi4O9 and BaPr2Ti4O12 two phases. Pr ions are distributed inthe BaTi4O9 grains and the segregation of Pr ions was observed on the grain boundaries of BaTi4O9/BaTi4O9.The content of Ti3 + and Ti2+ decrease in the BPT system composites due to the addition of BaTi4O9 fibers,which improved the dielectric properties of the system. BPT10 sample with 10 % BaTi4O9 fibers, has the bestdielectric properties in the system, its εr =64,tan δ = 1×10-4(at 1 MHz) , and it may be a potential candi-date for microwave dielectric ceramics.