Low-Field Magnetic Properties of Amorphous Alloys

The transition-metal-based ferromagnetic amorphous alloys made by the continuous splat-quenching method are excellent soft magnetic materials with low coercivity. Furthermore, their low-field magnetic properties are sensitive to heat treatments and can be greatly improved by such treatments. A review of low-field properties of these alloys such as anisotropy, remanence, and coercivity (as-received and after heat treatments) is presented together with data on the Fe₈₀B₂₀ amorphous alloy and the effect of fast-neutron irradiation.     

Structure and Mechanical Properties of Nanocomposites Based on an Amorphous Copolyester

Nanocomposites based on an amorphous copolyester (PCTG) were obtained by melt mixing, changing the screw speed and the nature of the surfactant, which differed in polarity and molecular volume. Using Young's modulus as a measure of the dispersion level, a less‐polar nature and a higher molecular volume of the surfactant appeared as positive structural factors for dispersion of the clay in the less‐polar PCTG. The Cloisite 20A, which led to the highest modulus (widest dispersion), was mixed at different contents with PCTG at the observed optimum screw speed (200 rpm). Intercalated structures were observed by WAXD and TEM. The dispersion was wide, as observed by TEM, and led to a large (77%) modulus increase after 7% organoclay addition and to important increases in both tensile yield stress and dimensional stability in creep.

     

Structural Relaxation in Amorphous Magnetic Screens

The structural relaxation is studied in amorphous magnetic screens produced by plasma deposition and explosive compacting from an amorphous metallic ribbon. Investigations are performed by different methods, such as differential scanning calorimetry (DSC), measurements of magnetic hysteresis properties, X-ray powder diffraction analysis, and electron probe X-ray microanalysis. It is found that the structural relaxation in the objects studied proceeds in the same way as in rapidly quenched glasses.     

无定型聚合物熔体的PVT特性

采用带有PVT口模的流变仪测定无定型聚合物熔体在压力0～50 MPa,温度453～563 K时的PVT(压力-体积-温度)特性曲线,分别用基团贡献修正胞腔模型(GCMCM)和胞腔模型对实测的PVT数据进行预测.结果表明:在实验中用基团贡献修正胞腔模型的比容平均预测误差较胞腔模型要大得多,其预测精度要略差于胞腔模型,这说明基团贡献修正胞腔模型的应用具有一定的局限性.同时还计算出了2种模型所对应的特征值,并分析了其特征值存在的共同点和差异的原因.     

Underestimated Properties of Nanosized Amorphous Titanium Dioxide

Titanium dioxide is one of the best described photosensitive materials used in photocatalysis, solar cells, self-cleaning coatings, and sunscreens. The scientific and industrial attention has been focused on the highly photoactive crystalline phase of titanium dioxide (TiO₂). It is commonly accepted that the smaller TiO₂ particles, the higher photoactivity they present. Therefore, titanium dioxide nanoparticles are massively produced and widely used in everyday products. The amorphous phase of titanium dioxide has been treated with neglect, as the lack of its photocatalytic properties is assumed in advance. In this work, the complex experimental proof of the UV-protective properties of the nano-sized amorphous TiO₂ phase is reported. Amorphous n-TiO₂ is characterized by photocatalytic inactivity and, as a consequence, low cytotoxicity to fibroblast cells. When exposed to UV radiation, cells with amorphous TiO₂ better survive under stress conditions. Thus, we postulate that amorphous n-TiO₂ will be more beneficial and completely safe for cosmetic applications. Moreover, the results from in situ FTIR studies let us correlate the low toxicity of amorphous samples with low ability to form hydroperoxo surface species.     

电沉积三元铁基非晶磁性合金薄膜的研究进展

叙述了电沉积三元铁基非晶磁性合金薄膜的工艺条件,包括Fe-Ni-S、Fe- Ni- Cr、Fe-Ni-W、Fe-Co-Ni及Fe-P-B等五种典型合金薄膜.介绍了铁基非晶磁性合金薄膜的耐蚀性、耐磨性、热稳定性以及磁学等功能性能,指出了未来铁基非晶磁性合金薄膜的研究方向.     

Preparation and Dielectric Properties of the Amorphous Basaltic Glass

Silicon - Due to the continuous basalt fiber is a kind of amorphous material, only the basaltic glass without crystallization can represent its dielectric properties. To explore the dielectric...     

球形非晶SiO2的制备及填充性能

以不规则形状熔融石英粉为原料,通过Ar-H2感应耦合等离子体技术制备球形硅微粉,并结合数值模拟研究加料速率对粉末球化率的影响。同时,将球化前后的粉体与环氧树脂、固化剂、固化促进剂按不同质量比经机械搅拌混合、超声分散和升温固化后制备得到环氧塑封材料。对球化处理前后粉末的形貌、物相、纯度和填充性能进行测试和分析。结果表明:经等离子球化处理后可得到表面光滑、分散性好、球化率100%的球形硅微粉。随加料速率的增加,石英粉的球化率降低。经等离子体处理后,粉体的松装密度、振实密度和流动性得到显著改善:松装密度由0.62g/cm3提高到0.91g/cm3,振实密度从0.92g/cm3提高到1.23g/cm3,粉末流动性提高到76s/(50g)。同时,等离子体处理使粉末纯度提高到99.95%。与原始粉相比,球形硅微粉具有更高的填充量,当球形硅微粉填充量为75%时,环氧塑封料的线膨胀系数为10.1×10-6/℃。     

镍基非晶合金镀层性能研究

采用化学镀及化学复合镀方法,得到了N i-P、N i-M o-P、(N i-M o-P)-A l2O3及(N i-M o-P)-PPS四种镀层;对各种镀层的形貌进行分析,并研究了随热处理温度升高各种镀层耐蚀性能的变化机理。结果表明:N i-M o-P基镀层的耐蚀性优于N i-P镀层;在85℃的10%H2SO4溶液中(N i-M o-P)-PPS镀层的腐蚀速率约是N i-M o-P镀层的1/3。     

Influence of an Amorphous Second Phase on the Properties of Yttria-Stabilized Tetragonal Zirconia Polycrystals (Y-TZP)

Y-TZP ceramics with various amounts of glassy intergranular phase were fabricated in order to investigate the effect of this amorphous phase on the properties of TZP. The presence of a liquid silicate phase not only enhanced sintering but also controlled the evolution of distinctly different grain morphologies, dependent on the amount of liquid phase present. The influence of the glass phase on the transformability of grains is discussed with respect to the room-temperature fracture toughness and surface degradation at 250°C.     

Magnetic Properties of Chromium Chrysoberyl

Magnetic susceptibility data between 4.2° and 300°K have been obtained for the (Al,Cr)₂BeO₄ solid-solution series. Chromium chrysoberyl is antiferromagnetic with a Néel temperature near 28°K; above 60°K it obeys the Curie-Weiss law with θ= 13OK and an effective atomic moment of 3.2 Bohr magnetons. A four-sublattice Weiss model consistent with the experimental results is presented.     

Magnetic Properties of Yttrium-Gadolinium-Iron-Aluminum-Indium Garnets

The saturation inductions of polycrystalline garnet materials with the general composition Y_3–x Gd_xFe_5–y–z Al_yIn_ZO₁₂ were determined. The compositions investigated included yttrium substitutions of 0 to 50%, aluminum substitutions of 0 to 10%, and indium substitutions of 0 to 10%. Temperature dependences of the saturation inductions are reported with special emphasis on materials having small temperature coefficients in the 20° to 100°C region.     

Magnetic Properties of Gadolinium-Yttrium-Iron-Indium Garnets

Polycrystalline garnets with the general composition Gd₃-_xY_xFe₅-_yIn_uO₁₂ were investigated. Ferrimagnetic resonance line widths at S - and X-bands and saturation induction are reported. The temperature dependence of the magnetization was determined on materials in which x = 0 to 3 and y = 0 to 1. Special emphasis is given to compositions having relatively stable magnetizations over the range 20° to 100°C.     

Preparation and Magnetic Properties of Some Hexagonal Magnetic Oxides

The preparation of nonoriented as well as magnetically oriented specimens of 2MeO · 2BaO·-6Fe₂O₃ and 2MeO·3BaO·12Fe₂O₃ is described. The MeO component is limited to NiO, ZnO, CoO, and CuO and mixtures of these in this discussion. The orienting apparatus and technique employed are briefly described. The magnetic permeability and loss as measured at 250 Mc is shown for many of these prepared compositions. The effect of the orienting magnetic field strength as well as firing temperature on the observed magnetic properties is discussed.     

Ni-Co磁性薄膜的电化学沉积及磁性能

研究了电流密度和温度对电沉积Ni-Co薄膜形貌、晶体结构及磁性能的影响。结果表明:随着电流密度的增加,Ni-Co薄膜的比饱和磁化强度先增大后减小,在200A/m2时达到最大值;电流密度对薄膜的结晶度和晶粒尺寸均有影响;在较高温度下制备的薄膜表面较粗糙,这是由于温度的升高致使析氢加剧。     

非晶态合金Fe-B-P催化活性和磁性的理论研究

采用原子簇方法,对倍受关注的Fe基非晶态合金Fe-B-P的催化活性和磁性进行研究.通过合理设计可调Fe含量的系列原子簇FenBP（n=1～4）可能构型三十余种,利用密度泛函理论（DFT）分别在单、三重态下进行优化计算.在不同多重度下,对所确定的原子簇FenBP（n=1～4）最稳定构型的几何结构、能量、能隙差、费米能级和d轨道布局数进行分析,结果表明：多重度对原子簇FenBP（n=1～4）几何构型影响较大;三重态比单重态稳定且催化加氢活性较好,其中三重态的Fe3BP活性最好;单重态的磁矩明显低于三重态,其中单重态的Fe4BP磁矩最小,表现出软磁性.     

High-Temperature Hydrogen Adsorption Properties of Precursor-Derived Nickel Nanoparticle-Dispersed Amorphous Silica

Nickel (Ni) nanoparticle-dispersed amorphous silica (Si–O) powders were synthesized from chemical solution precursors. The high-temperature hydrogen adsorption property of the precursor-derived composite powders was investigated in comparison with the amorphous Si–O and Ni at 773 K. Among the three powder samples, Ni nanoparticle-dispersed amorphous Si–O exhibited a unique reversible hydrogen adsorption property that was hardly detected on the amorphous Si–O and Ni. The increase amount of the reversibly adsorbed hydrogen was the highest for the composite samples at around the Ni content with a Ni/(Si+Ni) ratio of 0.2–0.3. The results strongly suggested that when the composite material is used in the form of a gas separation membrane, the reversibly adsorbed hydrogen property is thought to contribute to the additional increase in the number of solubility sites for hydrogen, which leads to a selective enhancement in the high-temperature hydrogen permeance at 773 K.     

非晶碳化硅量子点的制备及其光学性质研究

采用脉冲激光烧蚀法,以多晶3C-SiC陶瓷片为靶材,制备了悬浮于去离子水中的非晶SiC纳米颗粒.利用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、傅里叶变换红外吸收光谱(FTIR)、紫外可见吸收光谱(UV-Vis)和光致发光谱(PL)等测试手段对其形貌、结构和光学性质进行了分析.结果表明:这些纳米颗粒由大量的非晶SiC构成,粒径在8～9 nm,光学带隙为3.28 eV;样品表现出较强的光致发光,发光峰位于415 nm处,这主要是由于量子限制效应造成的.     

偶联剂对磁性丁腈橡胶磁性能的影响

分别选用2种硅烷偶联剂和4种钛酸酯偶联剂制备磁性丁腈橡胶（NBR）,研究偶联剂对磁性NBR磁性能的影响。结果表明：添加钛酸酯偶联剂的胶料的磁性能优于添加硅烷偶联剂的胶料,其中添加钛酸酯偶联剂A13的胶料的磁性能最优;随着偶联剂用量的增大,胶料的剩磁（Br）、内禀矫顽力（HCJ）和最大磁能积[（BH）max]先增大后减小,矫顽力（HCB）无明显变化规律;当钛酸酯偶联剂A13用量为磁粉用量的1%时,胶料具有最优的磁性能：B_r?0.224 T,H_CB?165 kA·m_-1^{,H_CJ?279 kA·m_-1,（BH）max?9.7 kJ·m_-3。}