The effect of the microstructure of porous alumina films on the mechanical properties of glass-fiber-reinforced aluminum laminates

The glass-fiber-reinforced aluminum laminates were obtained by anodizing aluminum alloy under anodizing voltage of 10, 20, and 30?V in the 200?g/L H₃PO₄ electrolyte. Scanning electron microscopy (SEM), short beam, and tensile tests were employed to determine the surface morphology, interlaminar shear strength (ILSS) and tensile strength of laminates, respectively. The results also show that the epoxy penetrates into the pores of the anodic films, and this is the mechanism of adhesion. The ILSS and tensile strength of the anodized specimens (under 20?V) respectively increased by approximately 50 and 15% comparing with those of the non-anodized specimens. This increase of mechanical properties results from the porous surface of aluminum providing greater mechanical interlocking to epoxy. The ILSS and tensile strengths of the anodized specimens increased with the increase of anodizing voltage from 10 to 20?V; however, it decreased when the voltage further increased to 30?V. It is considered that the microstructure evolution of the porous films has a significant effect on the mechanical properties of the laminates.     

Influence of silicon on the microstructure and mechanical properties of Zr-Si-N composite films

A series of Zr-Si-N composite films with different Si contents were synthesized in an Ar and N₂ mixture atmosphere by the bi-target reactive magnetron sputtering method. These films’ composition, microstructure and mechanical properties were characterized by energy dispersive spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy and nanoindentation. Experimental results revealed that after the addition of silicon, Si₃N₄ interfacial phase formed on the surface of ZrN grains and prevented them from growing up. Zr-Si-N composite films were strengthened at low Si content with the hardness and elastic modulus reaching their maximum values of 29.8 and 352 GPa at 6.2 at% Si, respectively. With a further increase of Si content, the crystalline Zr-Si-N films gradually transformed into amorphous, accompanied with a remarkable fall of films’ mechanical properties. This limited enhancement of mechanical properties in the Zr-Si-N films may be due to the low wettability of Si₃N₄ on the surface of ZrN grains.     

Modification of bonding properties and microstructure of resin-cement interface by coupling agents

To solve the problem of organic-inorganic light conductive composite interface features, transparent resin and cement matrix were used as carriers to further study features of the organic-inorganic interface formed by transparent resin and cement matrix and the interface modification of the coupling agent. The bond strength, micro-hardness, microstructure and surface morphology of a resin light conductive cementitious materials (RLCCM) interface were evaluated by tests of tensile and oblique shear, micro-hardness, environmental scanning electron microscopy, and atomic force microscope. The results show that the silane A-151 and aluminate coupling agent could significantly improve interface bond properties of RLCCM. At 7 d, the interface tensile bond strength of the silane A-151 and aluminate coupling agent increased by 117 and 105%, respectively. At 28 d, strength on average increased by 73%. At 7 d, interface shear strength the silane A-151 and aluminate coupling agent of 45° increased by 43 and 53%, respectively, At 28 d, strength on average increased by 40%. The transparent resin performance weakened region thickness up to 100 μm; the hardness of the transparent resin in the transition region was increased by 19.6 and 39.9%, respectively. Silane coupling agent A-151 and cement hydration products formed flat spherical particles with diameter of approximately 78 nm, and these particles mosaicked and fused in the surface of the hydrate; therefore, the surface became denser and smoother.     

温度对金刚石涂层膜基界面力学性能的影响

利用分子动力学方法建立了硬质合金基底金刚石涂层膜基界面模型, 并采用Morse势函数和Tersoff势函数相互耦合的方法来表征模型内原子间的相互作用关系, 在此基础上对不同温度(0–800 K)条件下硬质合金基底金刚石涂层膜基界面的力学性能进行了分子动力学仿真计算. 结果表明: 当温度由0 K上升到800 K的过程中, 金刚石涂层膜基界面拉伸强度呈下降趋势, 并且在0–300 K范围内下降趋势明显, 在300–800 K范围内下降趋势缓和; 体系能量随温度的变化具有相同的下降趋势.     

溅射压强对TiN/SiNx纳米多层膜微观结构及力学性能的影响

利用磁控溅射方法在不同溅射压强条件下制备了TiN/SiN_x纳米多层膜.多层膜的微观结构及力学性能分别用X射线衍射仪、原子力显微镜及纳米压痕仪来表征.结果表明随着溅射压强的增大,多层膜的界面变模糊,TiN层的择优取向由(200)晶面过渡到(111)晶面.与此同时,多层膜的表面粗糙度增大,硬度和弹性模量随溅射压强的增大而减小.多层膜力学性能的差异主要是由于薄膜的周期性结构及致密度存在差异所致. 关键词： x多层膜')" href="#">TiN/SiN_x多层膜 界面宽度 表面形貌     

Intermittent deposition and interface formation on the microstructure and magnetic properties of NiFe/Cu composite wires

In this work, magnetron sputtering in the form of continuous deposition or intermittent deposition modes was used to obtain NiFe/Cu composite wires. Based on the results, intermittent deposition mode led to the formation of an interface between deposited layers. A better crystallite and a little grain growth were found for the intermittently deposited wire. Good soft magnetic properties and large giant magneto-impedance (GMI) effect were exhibited by both composite wires. The GMI profile for the intermittently deposited composite wire was characterized by two peaks, which could be attributed to the difference in the magnetic properties of the inner and the outer magnetic layers. Annealing was introduced to the intermittently deposited wire so that the inherent stresses were partially relaxed. As a result, its GMI effect was enhanced and the magnetic properties of the two magnetic layers became similar. Hysteresis loops of the composite wires displayed different magnetic behaviors and hence further affirmed the GMI results.     

Effects of particle/matrix interface and strengthening mechanisms on the mechanical properties of metal matrix composites

A randomly distributed multi-particle model considering the effects of particle/matrix interface and strengthening mechanisms introduced by the particles has been constructed. Particle shape, distribution, volume fraction and the particles/matrix interface due to the factors including element diffusion were considered in the model. The effects of strengthening mechanisms, caused by the introduction of particles on the mechanical properties of the composites, including grain refinement strengthening, dislocation strengthening and Orowan strengthening, are incorporated. In the model, the particles are assumed to have spheroidal shape, with uniform distribution of the centre, long axis length and inclination angle. The axis ratio follows a right half-normal distribution. Using Monte Carlo method, the location and shape parameters of the spheroids are randomly selected. The particle volume fraction is calculated using the area ratio of the spheroids. Then, the effects of particle/matrix interface and strengthening mechanism on the distribution of Mises stress and equivalent strain and the flow behaviour for the composites are discussed.     

Influence of surface treatment on mechanical behaviour of fumed silica/epoxy resin nanocomposites

The present paper shows the potential of fumed silica as nano-reinforcements in polymers, by considering the limitations and challenges one has to face dealing with nanoparticles in general. The dominating effect of the manufacturing route and surface properties of fumed silica influencing the resulting degree of dispersion and the interfacial adhesion were investigated by electron microscopy (TEM, SEM). The resulting (fracture-) mechanical properties of the fumed silica/epoxy composites were investigated for volume contents of 0.5 vol% and below. Independent of the surface modification, static and dynamic modulus decreased slightly by adding the fumed silica. Hence, the fracture toughness K _Ic turned out to be significantly increased (54%) adding only 0.5 vol% of surface modified fumed silica.     

真空紫外辐射对碳/环氧复合材料性能的影响

 介绍了真空紫外线的模拟和射流式真空紫外辐射模拟设备的工作原理、技术参数及特点,并利用该设备及其它分析手段对环氧树脂浇铸体(EP648)和碳/环氧复合材料(C/E648)在真空紫外线辐照作用下的出气、质量损失率、层间剪切强度和表面状态的变化进行了研究。试验结果表明：真空紫外线辐照导致材料产生明显的出气效应,质量损失率呈现先递增后趋于平缓的趋势;17 280esh辐照剂量下,EP648的质量损失是C/E648的3.4倍,C/E648的层间剪切强度与辐照前相比下降了13.3%;环氧树脂破损较重,而碳纤维表面状态基本完好,并对内部的环氧树脂起到一定的保护作用。     

界面各向异性对双层铁磁薄膜自旋波性质的影响

在海森堡模型的基础上,采用界面参数化方法,将双层铁磁薄膜中自旋波本征值问题归结为联立求解能量约束方程和界面参数化方程.重点研究了界面各向异性对薄膜中自旋波本征问题的影响.结果表明:界面各向异性使对称模的波形在界面处呈现明显的钉扎现象,且界面模的能量随各向异性场增强而增大.     

Influence of precipitate-assisted nucleation on the microstructure and mechanical properties of Al-Mg-Si-Cu-Zn alloys

The influence of precipitation on the recrystallization nucleation and mechanical properties of Al-Mg-Si-Cu-Zn alloys was investigated by means of tensile tests, SEM, TEM, XRD and EBSD. The results reveal that there are distinct contributions from the various precipitates that form during annealing and that these critically influence the evolution of microstructure and its associated texture, as well as mechanical behaviour. In contrast to alloy sheets A, B, and C annealed at a lower temperature or for a shorter time, the T4P alloy sheet D with an annealing at 450°C for 3?h not only possesses almost identical strength and elongation, but also a higher average r (0.659) and n (0.313) values, and also a lower Δr (0.091) value. After solution treatment, the four alloy sheets are comprised of equiaxed grains with somewhat different grain sizes and different textures, but texture volume fraction and grain size in alloy sheet D both are decreased due to the effect of precipitate-assisted nucleation during solution treatment. The corresponding nucleation and growth mechanisms of recrystallization grains were established and the relationship between textures and r value in the four alloy sheets was also analyzed on the basis of a Visco-plastic self-consistent (VPSC) model.     

The gamma irradiation of PBO fiber on the mechanical and tribological properties of PTFE composites

The mechanical and tribological behavior of gamma irradiated poly(p-phenylene benzobisoxazole) (PBO) fiber filled polytetrafluoroethylene (PTFE) composites was investigated. The gamma irradiated PBO fiber composite had the highest inter-laminar shear strength value of all the combinations because its higher bond strength may have hindered a large fiber/matrix debonding. X-ray photoelectron spectroscopy results indicate that the contents of polar groups on the surface of gamma irradiated PBO fiber increase compared to PBO fiber. The wear tests were conducted on a ring-on-block apparatus using composite block against polished metal counterparts under dry sliding conditions. It can also be found that gamma irradiation treatment was helpful to the improvement of the anti-wear ability of the PTFE composite which was related to the abrasive wear mechanism.     

Damage and molecular changes under a laser beam in SEM‐EDX/MRS interface: a case study on iron‐rich particles

The control of damage to individual environmental particles by a laser beam during Raman spectroscopy carried out in ambient air is generally well understood. The nature and control of damage under vacuum conditions (e.g. in the scanning electron microscopy with energy X‐ray detection combined with micro‐Raman spectroscopy—interfaced SEM‐EDX/MRS) are more complex and less well comprehended. The physical and chemical processes that affect the damage caused to small particles by lasers still remain somewhat unclear, but certainly the atmosphere (vacuum/air) and the beam intensity have very significant influences. Furthermore, it has been determined that some particles (e.g. haematite), although stable under an electron beam, are damaged by the laser beam, hampering their analysis. Additionally, when simultaneous analyses by SEM/EDX and MRS are considered, the correct choice of the collection surface plays a crucial role. As a result, the following collection substrates were tested to determine their influence on the laser beam damage process to the particle: silver and aluminium foils and silicon wafers. A test study was performed using artificial examples of haematite (Fe₂O₃) particles. Exposure of Fe₂O₃ particles in vacuum to 514‐ and 785‐nm laser radiation often leads to their melting, transformation and evaporation. The dependence of the damage caused by the laser beam on the particle structure is reported here. Molecular and crystallographic changes have also been revealed. Formation of magnetite (as an effect of re‐crystallisation) and Raman inactive structures was detected. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of size of solvent molecules on structural and thermodynamic properties of the electrode/electrolyte interface

The influence of size of solvent molecules on the structural and thermodynamic properties of the interface between the electrode and electrolyte, using the solvent primitive model, was studied by grand canonical Monte Carlo (GCMC) simulations. The computer simulation results are compared with those obtained from the modified Poisson–Boltzmann (MPB) theory. The ionic singlet distribution functions show that the solvent molecules of low diameter favour the counter ion adsorption on the electrode. With increasing diameter of the solvent molecules, the mean electrostatic potential increases, while the integral and differential capacitances decrease. The integral capacitance curves obtained by MPB theory are in qualitative agreement with those obtained by the GCMC simulation although the theoretical results are overestimated.     

累积轧制Ti／AI复合材料的微观结构演变和力学性能研究

用累积轧制法成功制备了平均晶粒尺寸为200--300nm的超细等轴晶Ti／A1多层复合材料．研究了Ti／A1多层复合材料的微结构变化和力学性能．     

累积轧制Ti/Al复合材料的微观结构演变和力学性能研究

用累积轧制法成功制备了平均晶粒尺寸为200-300 nm的超细等轴晶Ti/Al多层复合材料. 研究了Ti/Al多层复合材料的微结构变化和力学性能.     

Influence of interface within the composite barrier on the tunneling electroresistance of ferroelectric tunnel junctions with symmetric electrodes

The interface with a pinned dipole within the composite barrier in a ferroelectric tunnel junction（FTJ） with symmetric electrodes is investigated.Different from the detrimental effect of the interface between the electrode and barrier in previous studies,the existence of an interface between the dielectric SrTiO₃ slab and ferroelectric BaTiO₃ slab in FTJs will enhance the tunneling electroresistance（TER） effect.Specifically,the interface with a lower dielectric constant and larger polarization pointing to the ferroelectric slab favors the increase of TER ratio.Therefore,interface control of high performance FTJ can be achieved.     

合金元素对Ag/Al界面性质影响的第一性原理研究

采用基于密度泛函理论的第一性原理方法,计算和分析Ag(111)/Al(111)界面体系的能量与电子结构,讨论Ag中加入的Be、Mg、Al、Ca、Ni、Sn合金化元素对Ag/Al界面性质的影响.结果表明:Ni原子倾向于界面处的取代位置,而Be、Mg原子倾向于靠近界面处的取代位置,Al、Ca、Sn原子倾向于远离界面处的取代位置;合金元素Be、Mg、Al、Ca、Ni、Sn的加入均会使Ag/Al界面的稳定性降低,其中Ca元素的影响程度最大,分离功降低到0.923 J/m~2,界面能增至0.703 J/m~2;通过电子结构计算结果分析认为,导致界面稳定性下降的主要原因应是合金化元素的加入使界面间形成的Ag-Al共价键强度降低引起.     

热处理对CH薄膜表面粗糙度及力学性能的影响

利用低压等离子体化学气相沉积法制备厚度约为7 m的辉光放电聚合物薄膜,将制备的薄膜样品放入通有氩气保护的热处理炉中加热至300 ℃,分别进行6,10,24 h的保温热处理。通过白光干涉仪观察分析了不同保温时间下辉光放电聚合物薄膜的表面粗糙度; 利用傅里叶变换红外吸收光谱分析了300 ℃条件下不同保温时间对薄膜结构的影响; 采用纳米压痕仪表征了不同保温时间热处理后,薄膜硬度及模量的变化。结果表明:随着保温时间的增加,薄膜的表面均方根粗糙度由12 nm降至4.43 nm。薄膜结构中甲基的相对含量减少,双键的相对含量增加,碳链变长,同时薄膜网络结构的交联化程度增强。硬度和模量随着保温时间的增加先减小后增大。