空心玻璃微珠/PP复合材料的制备及性能研究

采用共混与注塑工艺制备出空心玻璃微珠/PP复合材料.通过高倍偏光显微镜、傅里叶红外光谱仪(FTIR)、扫描电镜(SEM)等对材料的结构进行了表征,重点研究了未改性与改性的空心玻璃微珠对PP复合材料力学性能影响.结果表明:改性后的空心玻璃微珠在PP复合材料中分散均匀而且具有致密的内部结构,并明显的改善复合材料的拉伸、弯曲强度,最佳填充量为15%.     

空心玻璃微珠表面包覆Ni-P／Co-Fe-P复合镀层的研究

通过化学镀在空心玻璃微珠（HGM）表面沉积了镍磷合金颗粒镀层，利用偶联取代传统的粗化处理，结合适当的镀覆工艺实现了镀层与微珠的紧密结合并达到了均匀完整包覆；在此基础上，进行了镍磷镀层表面湿化学还原法包覆钴铁合金的研究。利用扫描电子显微镜、X射线能谱仪、X射线衍射仪及振动样品磁强计对包覆层的形貌、组成、晶体结构和改性后微珠的静磁性能进行了分析测试。结果表明，复合镀层由非晶态合金组成，其中镍磷镀层为单层颗粒膜，而后续沉积的钴铁合金镀层呈条带状生长于镍磷镀层表面；沉积钴铁合金后微珠的磁性有了明显改善。     

Effect of barium on diffusion of sodium in borosilicate glass

Diffusion coefficients of sodium in barium borosilicate glasses having varying concentration of barium were determined by heterogeneous isotopic exchange method using (24)Na as the radiotracer for sodium. The measurements were carried out at various temperatures (748-798 K) to obtain the activation energy (E(a)) of diffusion. The E(a) values were found to increase with increasing barium content of the glass, indicating that introduction of barium in the borosilicate glass hinders the diffusion of alkali metal ions from the glass matrix. The results have been explained in terms of the electrostatic and structural factors, with the increasing barium concentration resulting in population of low energy sites by Na(+) ions and, plausibly, formation of more tight glass network. The leach rate measurements on the glass samples show similar trend.     

Fatigue behaviour in hybrid hollow microspheres/fibre reinforced composites

This article presents the results of a current study concerning the influence of the addition of short fibres on the fatigue behaviour of syntactic foams. The material was obtained by vacuum-assisted resin transfer moulding adding hollow glass microspheres to an epoxy resin acting as binding matrix. Specimens with microsphere contents up to 50% and fibre reinforcement up to 1.2% in volume were tested at three-point bending at room temperature. Foams show significantly lower static and fatigue strength than an epoxy matrix. A significant decrease in the absolute strength with filler increase was observed, and even specific strength decreases for low filler contents and is nearly constant for the higher filler contents. Fatigue strength also decreases with the increase in filler content. The addition of glass fibre reinforcement produces only a slight improvement in flexure strength, while the addition of carbon fibres promotes an important improvement; a hybrid composite containing 0.9% carbon fibre is about 30% stronger than unreinforced foams. An improvement in fatigue strength more than 30% was obtained by the addition of small percentages of glass or carbon fibre.     

Determination of the absorptivity of OH in a sodium borosilicate glass

The absorptivity of OH in a sodium borosilicate glass has been determined. The method consisted of measuring the weight loss and the decrease in absorbance at 2825 nm after heat-treatment of polished slices of glass in a dry nitrogen atmosphere. The confusion in the literature involving water content and OH content of glasses is also discussed.     

浮力材料用国内外高性能空心玻璃微珠比较

简要介绍了国内外主要生产高性能空心微珠厂家及产品应用情况,以及当前国内外高性能玻璃微珠的制造技术、现状及性能比较,对国内外微珠制备浮力材料的性能进行比较,并提出了今后国内发展途径.     

A magnesium alloy matrix composite reinforced with metallic glass

Novel light-weight materials of advanced performance are now experiencing global interest due to the strong need to reduce energy consumption in land and air transportation sectors. Here we report on a novel magnesium alloy matrix composite material. The reinforcing phase in the magnesium alloy is a fine dispersion of metallic glass particles. The composite is sintered from the powder mixture of the alloy and metallic glass at a temperature slightly above the glass transition T_g of the metallic glass particles that is close to the Mg alloy’s solidus temperature. At the compaction temperature, the metallic glass acts as a soft liquid-like binder but upon cooling it becomes the hard reinforcement component of the composite. Processing, microstructure and mechanical properties of the composite are discussed.     

空心玻璃微球表面接枝聚苯乙烯及其性能研究

空心玻璃微球表面改性有利于改善其与基体间的相容性,提高复合泡沫性能.通过接枝聚苯乙烯对空心玻璃微球进行表面处理,采用SEM、IR、热失重等方法分析了反应条件对接枝的影响.结果表明,接枝反应过程中提高反应温度、延长反应时间有利于接枝率的提高,但温度过高会加速单体自聚,降低接枝率.接枝处理后,随着聚合物层的增厚,空心玻璃微球表面缺陷减小,破损率降低,抗压强度得到一定程度提高.     

空心玻璃微珠填充环氧复合泡沫材料的制备及性能表征

通过优化试验，以大量空心玻璃微珠填充环氧树脂体系制备出了密度低、强度高的复合泡沫材料，并对其密度和水下声学性能进行了表征。结果表明，所研制的轻质高强复合泡沫材料密度在0．3～0．5g／cm^3之间，且在高静水压下具有良好声学性能。     

Formation of silver nanoparticles in low-alkali borosilicate glass via silver oxide intermediates

A successful procedure has been worked out for the subsequent colouration of low-alkali borosilicate glass that comprises silver doping by silver/sodium ion exchange below the glass transformation temperature followed by thermal processing well above, at 750 °C. The particle formation process as studied by electron microscopy and optical spectroscopy revealed the formation of silver nanoparticles proceeding via silver oxide intermediates. The intermediate nanoparticles are supposed to result from a phase separation within the silver ion-doped glass. Their formation and succeeding transformation to silver nanoparticles upon thermal processing is accompanied by characteristic absorption peaks in the visible range which gradually convert to the surface plasmon resonance of spherical silver nanoparticles. The optical density of the silver-based colouration achieved this way assumes values comparable to those usually obtained with soda lime silicate glass.     

Synthesis and in vitro bioactivity of novel mesoporous hollow bioactive glass microspheres

The remarkable tissue-repairing bioactivity and biocompatibility of bioactive glass make it suitable for a wide range of applications. Here, novel mesoporous hollow bioactive glass microspheres (MHBGMs) with a uniform diameter range of 2-5 µm were prepared by a sol-gel method. Structural characterization indicated that the shell of hollow sphere had a mesopore size range between 2 and 10 nm and a thickness about 500 nm. The in vitro bioactivity test indicated that the novel structure exhibited high in vitro bioactivity. The uniform microspherical morphology and mesoporous hollow structure of MHBGMs, together with their high bioactivity, turn them into a good candidate as an injectable and drug-loading biomaterial for in vivo tissue regeneration and drug control release.     

Flexural properties of glass fiber reinforced composite with multiphase biopolymer matrix

The aim of this study was to evaluate flexural properties of glass fiber-reinforced composites with a multiphase biopolymer matrix. Continuous unidirectional E-glass fibers were preimpregnated with a novel biopolymer of poly(hydroxyproline) amide and ester. The preimpregnated fibers were then further impregnated in a co-monomer system of Bis-GMA-TEGDMA, which formed semi-interpenetrating polymer networks (semi-IPN) with the preimpregnated polymer. After light initiated polymerization of the monomer system, rectangular shaped bar specimens (n = 4) were tested by the three-point bending test. The control material was a fiber-reinforced composite with a Bis-GMA-TEDGMA-matrix only. The mean flexural strength of poly(hydroxyproline) amide preimpregnated fiber composite was higher than that of the control (FS = 888 vs. 805 MPa). The poly(hydroxyproline) ester preimpregnated fibers resulted in lower strength (FS = 541 MPa). The results of this study suggest that preimpregnation of glass fibers with poly(hydroxyproline) amide and the use of such fibers in fiber-reinforced composites with IPN polymer matrices, can reach relatively high mechanical properties.     

Structural,linear and third-order nonlinear optical properties of Cu nanocrystal in sodium borosilicate glass

Cu nanocrystals embedded in sodium borosilicate glass of varied Cu contents from 0.5 to 1.5 wt% have been successfully prepared through a sol–gel process. According to the results of X-ray diffraction (XRD) and the energy dispersive X-ray spectrometry (EDS), the metal Cu nanocrystals in cubic crystal system were well distributed inside glass matrix. Fourier Transform Infrared (FTIR) indicated the sodium borosilicate matrix had no major structural change for gels with different Cu contents. The optical absorption peaks due to the surface plasmon resonance of Cu particles were observed in the wavelength range of 550–600 nm. The absorption peak showed a red-shift trend with increasing Cu contents from 0.5 to 1.5 wt%. Transmission electron microscopy (TEM) revealed the existence of spherical Cu nanocrystals in the matrix. The diameter of Cu nanocrystals varied from 1 to 3.5 nm. Furthermore, the third-order nonlinear optical properties were investigated by Z-scan technique at 800 nm. Experimental results indicated the Cu nanocrystals have obvious positive refractive nonlinearities and reverse saturated absorption performance.     

Microstructures and the third-order optical nonlinearities of semimetal Bi nanocrystals in the sodium borosilicate glass

The sodium borosilicate glass doped with semimetal Bi nanocrystals is prepared by employing both sol-gel and atmosphere control methods. Microstructures and the third-order optical nonlinearities of the glass are investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), and Z-scan technique. The results show that semimetal Bi nanocrystals in hexagonal crystal system with spherical shape have formed uniformly in the glass, and the size of these nanocrystals is almost less than 40 nm. Furthermore, the third-order optical nonlinear refracitve index γ, absorption coefficient β, and susceptibility χ⁽³⁾ of the glass are determined to be 9.40 × 10⁻¹⁷ m²/W, 1.25 × 10⁻⁹ m/W, and 6.80 × 10⁻¹¹ esu, respectively.     

Creep crack growth in a short glass fibres reinforced polypropylene composite

In this paper the creep crack propagation in a short glass fibre reinforced polypropylene composite has been investigated at various temperatures in the range from 32 to 60°C. Creep crack speed (da/dt) resulted initially decreasing till a minimum value, and then gradually increasing up to instability and fracture. Both initial and minimum crack speed values were found to strongly increase as test temperature increased. Moreover, isothermal curves of the applied stress intensity factor K_appl as a function of the crack speed (da/dt) were obtained at various temperatures. Portions of these curves in the stable crack acceleration region were hence shifted along the da/dt, axis according to a time-temperature reduction scheme, thus allowing the construction of a creep crack propagation master curve. The shift factor values, a_T for the creep crack propagation master curve appeared to be higher than those obtained, in the same temperature range, from dynamic mechanical measurements in a linear viscoelastic regime.     

Fabrication of hollow mesoporous NiO hexagonal microspheres via hydrothermal process in ionic liquid

The novel NiO hexagonal hollow microspheres have been successfully prepared by annealing Ni(OH)₂, which was synthesized via an ionic liquid-assisted hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption and Fourier transform infrared spectrometer (FTIR). The results show that the hollow NiO microstructures are self-organized by mesoporous cubic and hexagonal nanocrystals. The mesoporous structure possessed good thermal stability and high specific surface area (ca. 83 m²/g). The ionic liquid 1-butyl-3methylimidazolium tetrafluoroborate ([Bmim][BF₄]) was found to play a key role in controlling the morphology of NiO microstructures during the hydrothermal process. The special hollow mesoporous architectures will have potential applications in many fields, such as catalysts, absorbents, sensors, drug-delivery carriers, acoustic insulators and supercapacitors.     

Interface structure and fractography of a magnesium-alloy,metal-matrix composite reinforced with SiC particles

The interfacial structure in SiC-particle-reinforced, as-cast and heat-treated magnesium-alloy-matrix composites was investigated using analytical electron microscopy. No extensive chemical reactions were observed between the magnesium and the SiC particles or the SiC and the eutectic phase. However, most of the eutectic phase appeared to nucleate at the surface of the SiC particles. In addition to the lamellar eutectic, a fine eutectic and Mg₂Si particles have been identified at the SiC surface using nanoprobe micro-analysis. As with the aluminium base composite, precipitation was observed to take place on dislocations, and dense precipitation was found to occur in the stress fields around the SiC particles. Examination of the fracture surface indicated that the bonding between the SiC/eutectic is stronger than between the SiC/magnesium matrix. Intergranular cracks have been observed both in the fracture surface and also in a polished and etched section. The fracture surface tends to exhibit a more brittle morphology in the composite than is observed in the alloy.     

Discrete failure mode detection in a woven SiC cloth reinforced glass composite

Single layer silicon carbide cloth reinforced glass composites were fabricated and subjected to three-point bending in order to develop better models of failure mechanisms. Acoustic emission (AE) monitoring was also performed during the bend tests to help isolate these mechanisms. During the basic flexural tests, discrete failure modes, which were often not visible from specimen surfaces, displayed their existence through characteristic load-deflection curve unloading regions and abrupt changes in acoustic activity. Microscopic three-point bend tests were then performed to elaborate on the results of the conventional bend tests. Observations made during the microscopic bend tests provided a one-to-one correlation with load-deflection curve anomalies and acoustic emission activity. As a result of the different mechanical, optical and acoustical techniques used, discrete failure mechanisms for the cloth reinforced ceramic matrix composite (CMC) were conclusively established.