机械合金化在金属陶瓷制备领域的应用

指出了机械合金化的主要原理为高效球磨作用 ,并概述了机械合金化的主要应用领域 ,总结了该方法的主要特点 ,以及在制备复相陶瓷材料中的发展方向和应解决的问题     

Dynamic mechanical analysis of FRP composites based on different fiber reinforcements and epoxy resin as the matrix material

Three-ply composite laminates prepared from E-glass or N-glass chopped strand mats (CSMs) and jute (J) fabrics as reinforcing agents and amine-cured epoxy resin as the matrix material were subjected to dynamic mechanical thermal analysis at a fixed frequency of 1 Hz over a temperature range of 30–180°C. The volume fraction of fibers ranged between 0.21 and 0.25. The reinforcing effect for the three fibers is in the order E-glass > N-glass ≫ jute. Glass-reinforced composites show a higher storage modulus (E′) than that of jute-reinforced composites. The E′ values of glass-jute hybrid composites lie between those of glass-reinforced and jute-reinforced composites. Odd trends in temperature variability of the loss modulus (E′) and the damping parameter, tan δ, and in the glass transition temperature (T_g) for the three different unitary and four different hybrid composites are interpreted and understood on the basis of odd differences in (1) the chemical nature and physical properties of the three different fibers (E-glass, N-glass, and jute), (2) the void content and distribution, (3) the thermal expansion coefficients of the main phases in the composites, (4) the degree of matrix stiffening at or near the fiber-matrix interface, and (5) the extents of matrix softening in the zone next to the interface. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2467–2472, 1997     

金属基复合材料的研究进展

概述了金属基复合材料的发展历史和制造方法,着重介绍了不同种类金属基复合材料的研究现状和应用前景,指出了金属基复合材料研究过程中存在的问题和今后发展的方向。     

纳米材料改性水性聚氨酯的研究进展

综述了纳米材料改性水性聚氨酯(PU)研制的进展情况,介绍了纳米材料在水性PU乳液中的分散方法和水性PU纳米复合材料的制备方法,并对纳米技术在水性PU中的发展应用作了展望。     

Effects of Preform Shear on Tensile Properties of a Woven C/SiC Composite

This article addresses effects of weave defects in an angle‐interlock C‐fiber preform on the tensile properties of the resulting fully processed C‐fiber/SiC‐matrix composite. For this purpose, a preform was intentionally sheared in a controlled manner after weaving. The resulting distortions were quantified by analyzing high‐resolution images of the preform surface after the first step of matrix processing, while the tows were still clearly visible. Comparisons are made of tensile test results on specimens cut from this composite panel and from a pristine panel in select loading orientations. Strain maps obtained by digital image correlation are used to identify local strain variations that are attributable to weave defects. The results are discussed in terms of: (i) the shear‐normal coupling that arises in loading orientations of present interest, and (ii) the geometric effects of tow misalignment on tow continuity along the specimen gauge length. The composite is found to perform in a robust manner, in the sense that the tensile properties are not sensitive to the presence of the defects.     

SiC_f/Ti复合材料在航空发动机中的应用进展

综述了碳化硅纤维增强钛基(SiCf/Ti)复合材料国外的研究和应用现状,以及SiCf/Ti复合材料制备技术的研发进展,分析了这类先进复合材料优越的力学性能。综述分析表明,SiCf/Ti复合材料具有较高的比强度和比刚度、高的抗疲劳和抗蠕变特性,在未来航空发动机上有广阔的应用前景。同时指出,由于目前SiCf/Ti复合材料制备成本昂贵,其应用进展受到严重制约,建议对该材料大力开展系统性应用研究。     

Preparation and properties of an oxide fiber‐reinforced silica matrix composite

Oxide (Nextel? 440) fiber‐reinforced silica composites, with the density and porosity of 1.97 g/cm³ and 21.8%, were prepared through sol‐gel. Their average flexure strength, elastic modulus, shear strength, and fracture toughness at room temperature were 119.7 MPa, 25.6 GPa, 10.8 MPa, and 4.0 MPa·m^1/2, respectively. The composites showed typical toughened fracture behavior, and distinct pullout fibers were observed at the fracture surface. Their mechanical properties were performant up to 1000°C, with the maximum flexural strength of 132.2 MPa at 900°C. Moreover, the composites showed good thermal stability, even after thermal aging and thermal shock at elevated temperatures.     

An investigation on flowability and compressibility of AA 6061100 − x-x wt.% TiO2 micro and nanocomposite powder prepared by blending and mechanical alloying

This work investigates the relationships between the components of powders, namely, the powder surface morphology, the flow characteristics and the compressibility of low-energy (microcomposite) and high-energy (nanocomposite) ball milled powders of Al 6061 alloy reinforced with TiO₂ particles. The morphology of the above powder as the function of reinforcement and the milling time was studied by using the scanning electron microscope (SEM). The changes in powder characteristics such as the apparent density, tap density, true density and flow rate were examined by the percentage of reinforcement and milling time. The cohesive nature of the powder was also investigated in terms of Hausner ratio and Kawakita plot. Further, the particle/agglomerate size of low-energy and high-energy ball milled powders was explained by the laser particle size analyzer. X-ray peak broadening analysis was used to determine structural properties of mechanically alloyed powders. The compressibility behavior was examined by the compaction equation proposed by Panelli and Ambrosio Filho to investigate the deformation capacity of the powder. The compressibility behavior, namely, the densification parameter (A) of the microcomposite powder (irregular morphology) was decreased significantly with increasing TiO₂ content due to the disintegration of TiO₂ particles and the cluster formation followed by its agglomeration. The compressibility behavior, namely, the densification parameter (A) of the nanocomposite powder (equiaxed and almost spherical) was decreased slowly with increasing TiO₂ content due to work hardening on the matrix powder. With increased milling time, the compressibility behavior of AA 6061-10 wt.% TiO₂ composite powders increased up to 30 h of milling due to embedding of TiO₂ particles with matrix and changes in powder morphology and finally decreased after 40 h due to work hardening effect.     

Effect of high energy ball milling on strengthening of Cu-ZrO2 nanocomposites

In this paper, copper matrix nanocomposites reinforced by 5 and 10?wt% ZrO₂ particles were produced by mechanical milling technique at different milling times. The produced nanocomposite powders were investigated by X-ray diffraction technique and transmission electron microscopy. The effect of high energy ball milling on the morphology, microstructure and microhardness of the produced composites has been investigated. After that cold compaction was applied to the prepared powders under a pressure of 700?MPa and sintered at 950?°C for 2?h in hydrogen atmosphere. The results showed that increasing milling time improves microhardness of the prepared nanocomposites. The microhardness of Cu-10%ZrO₂ after 20?h milling is 3.76 times larger than pure Cu. This improvement is attributed firstly to the presence of ZrO₂ nanoparticles in addition to the improvement coming from the grain refinement and crystallite size reduction occurred due to mechanical alloying. So, in spite of the crystallite size of Cu-10%ZrO₂ nanocomposite is reduced to 10.75?nm compared to 105.5?nm for pure Cu, the presence of ZrO₂ nanoparticles plays a major role on mechanical properties improvement.     

Study of material removal mechanisms in grinding of C/SiC composites via single-abrasive scratch tests

As one of the ceramic matrix composites (CMCs), carbon fiber-reinforced silicon carbide matrix (C/SiC) composites are promising materials used in various engineering applications owing to their superior properties. Precision surface grinding has been widely applied in the machining of CMC composites; however, the material removal mechanisms of C/SiC composites have not been fully elucidated yet. To reveal the material removal mechanisms in the grinding of chemical vapor infiltration-fabricated C/SiC composites, novel single-abrasive scratch tests were designed and conducted in two typical cutting directions. The experimental parameters, especially the cutting speed, conformed to the actual grinding process. The results show that the grinding parameters (feed rate, spindle speed, depth of cut, and cutting direction) have significant influences on the grinding forces, surface integrity, and affected subsurface region. The tangential force is in general larger than the normal force at the same cutting depth. Furthermore, both the tangential and normal forces in the longitudinal cutting direction are larger than those in the transverse cutting direction. The impacts and abrasive actions at the tool tip mainly caused the material removal. The predominant material removal mode is brittle fracture in the grinding of unidirectional C/SiC composites, because the damage behaviors of the C/SiC composites are mainly the syntheses of matrix cracking, fiber breakage, and fiber/matrix interfacial debonding. These results are rationalized based on the composite properties and microstructural damage features.     

Delamination Cracking in a Laminated Ceramic-Matrix Composite

Delamination crack propagation has been investigated in a laminated fiber-reinforced ceramic-matrix composite. The crack growth initiation resistance has been shown to be dominated by the critical strain energy release rate for the matrix. However, the resistance increases with crack extension because of bridging effects associated with intact fibers and, in some cases, intact segments of matrix. The delamination cracks also assume a steady-state trajectory within a 0° layer close to the 0°/90° interface.     

Design of a New Zirconia–Alumina–Ta Micro‐Nanocomposite with Unique Mechanical Properties

2Y‐TZP/Al₂O₃ hybrid nanoparticles prepared by CO₂ laser covaporization (CoLAVA) were wet mixed with biocompatible lamellar Ta metal particles (20 vol%) and consolidated by spark plasma sintering. The microstructure and mechanical properties of this novel ceramic–metal composite have been studied. The achieved results demonstrate that both the homogeneity of the 2Y‐TZP/Al₂O₃ nanocomposite matrix and the reinforcement with a micrometer‐sized ductile phase are prerequisites for the successful design and fabrication of ceramic–metal composites with high strength (1300 MPa), enhanced fracture toughness (16 MPa·m^1/2), and improved low‐temperature degradation resistance.     

Some Aspects of Stability and Nanophase Formation in Quasicrystals during Mechanical Milling

Non-equilibrium processing and other related techniques can activate quasicrystalline structures to a higher energy level and enable them to attain various stable/metastable structures. During mechanical milling of quasicrystalline alloys, the stability of the complex structures is of immense importance from a scientific and technological point of view. The evolution of nanoquasicrystalline, nanocrystalline, and amorphous phases and their composites has been observed in the course of milling. The experimental results for mechanical alloying of elemental powders (required for the synthesis of quasicrystals) and mechanical milling of quasicrystals are discussed. The salient features observed in quasicrystals during other non-equilibrium processing are highlighted. Nanospinel formation from the Al-based quasicrystalline precursor is mentioned.     

Fabrication of High Performance Fly Ash/Mica/Poly(ether-ether-ketone) Hybrid Composites

This paper deals with the preparation and characterization of poly(ether-ether-ketone) (PEEK) fly ash mica hybrid composites containing filler 5:15, 10:10 and 15:5 fly ash mica combinations loading. The performances and properties of the resulting 20 wt% loading of fly ash mica/PEEK hybrid composites were examined. The resulting hybrid composites of 20 wt% fly ash and mica with varying combinations exhibit the optimum improvement of mechanical properties and dielectric strength. MDSC showed the decrease in the crystallization temperature (Tc) with varying combinations of fly ash and mica. The morphology of fly ash/mica/PEEK hybrid composites was studied by SEM.     

固相反应法制备超细氧化铈的球磨工艺优化研究

以铈盐与草酸为原料,室温下通过机械球磨固相反应法合成前驱体草酸铈,经热分解得到超细氧化铈粉末。利用TG-DSC表征了前驱体粉末在热分解过程中的变化情况,利用X射线衍射(XRD)、扫描电镜(SEM)表征了产物的组成、大小和形貌。实验对比研究得出的较佳工艺为:机械球磨,填充率为40%,球料质量比为15∶1,球磨时间为2.5 h,400℃下煅烧2 h。在此条件下制备的氧化铈颗粒粒径约为300 nm,大小均匀,颗粒分散性较好。     

Effect of layering pattern on dynamic mechanical properties of randomly oriented short banana/sisal hybrid fiber–reinforced polyester composites

Dynamic mechanical test methods have been widely employed for investigating the structures and viscoelastic behavior of polymeric materials to determine their relevant stiffness and damping characteristics for various applications. Randomly oriented short banana/sisal hybrid fiber–reinforced polyester composites were prepared by keeping the volume ratio of banana and sisal 1 : 1 and the total fiber loading 0.40 volume fraction. Bilayer (banana/sisal), trilayer (banana/sisal/banana and sisal/banana/sisal), and intimate mix composites were prepared. The effect of layering pattern on storage modulus (E′), damping behavior (tan δ), and loss modulus (E″) was studied as a function of temperature and frequency. Bilayer composite showed high damping property while intimately mixed and banana/sisal/banana composites showed increased stiffness compared to the other pattern. The Arrhenius relationship has been used to calculate the activation energy of the glass transition of the composites. The activation energy of the intimately mixed composite was found to be the highest. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2168–2174, 2005     

CF／5228复合材料研究

用湿法缠绕技术制作了CF/5228预浸料,对热压罐固化的CF/5228复合材料的室温、高温干态和湿态力学性能进行了研究。与其它复合材料相比,M40J/5228复合材料的各项力学性能均有很大程度的提高,且具有优异的耐湿热性能,在130℃干态和湿态下,其弯曲强度、模量和层间剪切强度的保持率较高。     

A multiscale methodology quantifying the sintering temperature‐dependent mechanical properties of oxide matrix composites

A novel methodology combining multiscale mechanical testing and finite element modeling is proposed to quantify the sintering temperature‐dependent mechanical properties of oxide matrix composites, like aluminosilicate (AS) fiber reinforced Al₂O₃ matrix (AS_f/Al₂O₃) composite in this work. The results showed a high‐temperature sensitivity in the modulus/strength of AS fiber and Al₂O₃ matrix due to their phase transitions at 1200°C, as revealed by instrumented nanoindentation technique. The interfacial strength, as measured by a novel fiber push‐in technique, was also temperature‐dependent. Specially at 1200°C, an interfacial phase reaction was observed, which bonded the interface tightly, as a result, the interfacial shear strength was up to ≈450 MPa. Employing the measured micro‐mechanical parameters of the composite constituents enabled the prediction of deformation mechanism of the composite in microscale, which suggested a dominant role of interface on the ductile/brittle behavior of the composite in tension and shear. Accordingly, the AS_f/Al₂O₃ composite exhibited a ductile‐to‐brittle transition as the sintering temperature increased from 800 to 1200°C, due to the prohibition of interfacial debonding at higher temperatures, in good agreement with numerical predictions. The proposed multiscale methodology provides a powerful tool to study the mechanical properties of oxide matrix composites qualitatively and quantitatively.     

Study on interfacial properties of unidirectional flax/vinyl ester composites: Resin manipulation on vinyl ester system

Flax fibers are widely used as reinforcements in bio‐based polymer matrix composites. This study investigated the hydrophilic nature and surface purity of flax fiber that affects fiber/matrix adhesion in combination with hydrophobic structural polymers via matrix modification and the utilization of fiber treatment, specifically in a flax/vinyl ester (VE) composite. A new method to manipulate the vinyl ester system with acrylic resin (AR) was developed to produce flax reinforced. On the other hand, different types of chemical and physical treatments were applied on the flax fiber. FTIR was applied to evaluate the effects of surface treatments. Dynamic mechanical analysis (DMA) was used to analyze the unmodified and modified VE resin system. The surface of untreated and treated flax fibers and their composites were analyzed by scanning electronic microscopy (SEM). Sodium ethoxide‐treated flax/VE with 1% (wt) AR caused the best mechanical performance among all the flax/VE composites evaluated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

镍基Al2O3-TiB2金属陶瓷粉末机械合金化机制研究

本文研究了添加不同质量分数的Ni对机械合金化合成Al2O3-TiB2金属陶瓷粉末的影响.应用X射线衍射仪、扫描电镜对球磨不同时间后的产物进行了物相和颗粒形貌的分析.结果表明:不含Ni粉的Al、TiO2和B2O3的混合粉末,在机械合金化12 h后,按照化学方程式10Al+ 3TiO2+ 3B2O3=5Al2O3+ 3TiB2发生固相反应,获得Al2O3、TiB2复相组织;当加入Ni粉后Al、TiO2和B2O3的混合粉末,由于在机械球磨过程中,Ni优先与Al形成中间相NiAl,NiAl比Al更容易与TiO2及B2O3发生反应,按照化学方程式10NiAl+ 3TiO2+ 3B2O3=5Al2O3+ 3TiB2+10Ni发生固相反应,获得Al2O3、TiB2复相组织;使得机械合金化时间随着Ni粉加入量的增大而减小,当添加质量分数为5％、10％、15％、20％、25％和30％的Ni粉后,分别在机械合金化12 h、10 h、8h、8h、6h和4h后,得到Al2O3、TiB2复相组织.