离子聚合物金属复合材料的力电耦合模型

提出了一种基于不可逆热力学和纯弯曲理论的力电耦合模型,以描述和预测离子聚合物金属复合材料的力电特性.力电耦合模型的表达形式可简化为含有两个驱动力(电场E和压力梯度▽p)的线性等式,主要依据离子传输、电场作用和弹性变形之间的耦合关系预测IPMC的力电特性;采用纯弯曲理论近似描述了IPMC的受力特征.这个力电耦合模型可解释IPMC材料的驱动特性和传感特性,能较好地预测IPMC在直流激励下的响应,误差在-7%以内.     

Ag型IPMC柔性驱动器的制备及性能

为了降低成本并改善材料性能,采用银替代铂制备IPMC电极。基于渗透还原工艺采用化学沉积方法制备了Pt基、Pt-Ag基和Ag基三种IPMC柔性驱动器试件。对试件的SEM和XRD分析结果表明本文提供的方法可以有效地将电极金属沉积在基膜中,且呈梯度分布;对样件的致动效果以及表面电阻特性测试结果表明Ag基IPMC驱动器具有最好的致动变形能力和最低的表面电阻。在相同尺寸与约束条件下,Ag基IPMC在1.5V时产生90°变形,Pt型与Pt-Ag型IPMC分别在3V和4V驱动电压下产生60°变形。     

离子聚合物金属复合材料驱动器的制备与性能研究

以离子聚合物金属复合材料(IPMC)作为驱动器,应用于新型仿变形虫机器人运动中,为满足运动系统参数要求,研究了IPMC智能材料的结构、弹性模量与加电变形性能.实验制备了IPMC材料,采用SEM对其表面及断层电极金属形貌进行表征,纳米压痕仪测量其硬度及弹性模量,对加电形变性能采用跟踪记录材料变形过程,并运用图像处理,展示...     

具有梯度结构的三维IPMC的制备及表征

离子聚合物金属复合材料(ionic polymer metal composite,IPMC)是一种离子型电活性聚合物,具有驱动电压低、位移变形量大、反应迅速和质量轻等优点,作为新型的电致动材料具有广阔的应用前景。但是现有的IPMC电致动材料存在输出力小和非水工作时间短的缺点。通过制备厚度上具有梯度变化的三维IPMC来提高IPMC的驱动性能;采用不易电解挥发、稳定性较好的乙二醇作为IPMC的工作介质,延长IPMC的非水工作时间。研究结果表明,在相同幅值的正弦交流电压下,具有一定梯度结构的IPMC能够显著提高其形变位移和输出力,幅值为3.5V时,形变位移和输出力较相同质量厚度的平面型IPMC分别提升了7.0%和47.9%;用乙二醇置换水作为工作介质的平面型IPMC,其非水工作时间得到大幅提升,从150s延长至300s。IPMC电机械输出性能的提升和非水工作时间的延长对于IPMC在驱动领域的进一步应用开发具有重要意义。     

Q235表面辉光等离子渗镀TiN耐蚀性研究

利用等离子辉光放电溅射技术,在碳钢表面复合渗镀形成TiN扩散层和沉积层.表面成分检测渗镀层呈梯度材料分布,表面钛原子和氮原子之比,符合TiN相结构.渗镀层总深度约有15μm,表层TiN约有4μm.渗镀层成分检测表明,与基体之间呈梯度分布.X射线衍射结果表明,渗镀层表面为TiN,其中(200)晶面的衍射峰最强,具有明显的择优取向.TiN复合层在H2S溶液中的腐蚀行为表明:辉光合成的TiN涂层可以提高材料在富液溶液中的耐蚀性能,与PVD沉积TiN试样和基体低碳钢试样相比耐蚀性分别提高了5.76,49.76倍.     

IPMC人工肌肉的制备工艺研究

为了降低成本并改善材料性能,采用导电性良好的Ag作为IPMC人工肌肉两侧金属电极,利用还原法制备IPMC,并设计了测试IPMC人工肌肉性能的平台,对样件使用寿命进行测试。结果表明,改良后的制备工艺,使制备周期缩短了30%,IPMC样件制备质量均能达到使用要求;未经表面保水处理的IPMC在空气中的动作次数为60次左右,而经过表面保水处理的IPMC在空气中的动作次数可以提高到90次,对IPMC表面经过保水处理可以使其使用寿命提高50%左右。     

各向异性复合材料开孔板拉伸强度预测及模型验证

基于有限断裂力学方法建立了一种预测多向复合材料开孔板拉伸强度的通用和半经验模型。该模型同时采用基于应力形式的失效准则和基于能量形式的失效准则预测失效。模型仅需铺层弹性常数、无缺口层合板的强度以及0°铺层的断裂韧性等参数。基于线弹性断裂力学建立了多向复合材料层合板的断裂韧性与0°铺层断裂韧性之间的关系, 进而预测了任意铺层复合材料开孔板发生纤维主导拉伸失效时的强度。将模型预测结果与开孔板拉伸强度的试验数据进行了对比验证, 预测误差最大为9.7%, 与点应力和平均应力等方法的对比表明, 该模型的预测精度高于传统的特征长度方法。      

金属─陶瓷梯度材料的热弹塑性分析

本文对金属-陶瓷梯度材料的稳态热弹塑性行为进行了研究.文中首先采用平均场和自洽弹塑性微观力学方法预测了金属-陶瓷梯度材料的非弹性性能,然后用非线性有限元法计算了材料制备过程中的热弹塑性应力.结果表明,梯度材料的热弹塑性行为对梯度材料的热应力缓和性能有显著影响.     

金属─陶瓷梯度材料的热弹塑性分析

本文对金属-陶瓷梯度材料的稳态热弹塑性行为进行了研究.文中首先采用平均场和自洽弹塑性微观力学方法预测了金属-陶瓷梯度材料的非弹性性能,然后用非线性有限元法计算了材料制备过程中的热弹塑性应力.结果表明,梯度材料的热弹塑性行为对梯度材料的热应力缓和性能有显著影响.      

离子聚合物-金属复合物材料的研究进展

离子聚合物-金属复合物(IPMC)是具有电响应特性的复合材料,既能作为致动器又可以用作传感器,具有广泛的应用前景,是材料领域研究的热点。概述了IPMC的制备过程及致动机理,从IPMC的离子交换膜材料和电极材料研究方面综述了IPMC的发展情况,并介绍了材料的组成和结构对IPMC的响应速度、弯曲位移、输出力等性能的影响。探讨了IPMC目前存在的问题,并展望未来的发展前景。     

Infrared reflection-absorption spectra of metal-effect coatings

The results of studies of infrared reflection-absorption spectra of metal-effect coatings are presented in this paper. Such coatings consist of metallic flakes that are dispersed in a polymer binder. The spectra show two distinct phenomena. One is due to the polymer matrix. The other is due to metallic flakes that are dispersed inside the layer. The polymer binder causes narrow spectral lines that give a thickness-dependent intensity and position. Metallic flakes change the average baseline of this spectrum over the entire infrared spectral region. This particular effect was evaluated using a simple rough-surface model. Two parameters of the model, the root-mean-square roughness and the correlation length of the rough surface, described the reflection of the partial beams on the metal flake surfaces and scattering on flakes boundaries. The other two parameters are the specular reflectance and the diffuse reflectance of the plane untextured interface between the polymer matrix and the metal flake surface. Various metal-effect coatings within the same polymer binder were analyzed. The effect of each metal flake dispersion was evaluated by the parameters within the rough-surface model. The results were analyzed in terms of the size and the loadings of flakes that were used in the coatings.     

Novel multi-layer polymer-metal structures for use in ultrasonic transducer impedance matching and backing absorber applications

This paper presents a novel design principle for designing multilayer polymer-metal structures which are well suited for front surface impedance conversion (matching) and for back surface acoustic absorption. It is shown that a polymer layer with an outer metal layer, when loaded by a low impedance propagation medium, acts as an efficient impedance converter. The resulting impedance seen at the inner polymer surface is increased and the structure provides the same performance as a traditional quarter-wavelength matching layer. Experimental evidence is also shown for a double-matching scheme for a lead zirconate titanate (PZT) transducer using an inner polymer-metal multilayer and an outer polymer quarterwavelength layer, resulting in a 55% bandwidth at 2.6 MHz with air backing. Also, it is theoretically shown that multiple layers of a lossy polymer adhesive-metal structure produce low propagation velocity and high absorption. Experimental proof of this ultrasonic multilayer backing absorber is provided. Design theories based on both a simplified mass and spring model and a rigorous one-dimensional wave model have been developed and show fair agreement.     

Surface properties and adhesion mechanisms of graft polypropylenes

Improvement of the adhesion capacity of polypropylene to aluminium can be obtained by adding a small quantity of maleic anhydride grafted polypropylene to the polymer. With increasing maleic anhydride content, the peel strength of the polymer-aluminium assembly first increases due to migration, orientation and chemical bonding, and then decreases as a result of the formation of a weak boundary layer, made of the low molecular weight grafted polymer chains. This study stresses the importance of two phenomena in adhesion: the restructuring of the polymer at the metal interface and the formation of an interphase.     

Plasmon-triggered living photopolymerization for elaboration of hybrid polymer/metal nanoparticles

Surface plasmon resonance can be used to manipulate light at the nanoscale. It was used here to trigger photopolymerization of an atom transfer radical polymerization (ATRP) molecular system, leading to a thin polymer shell at the surface of the metal nanostructure. The polymerization can be reactivated from the first polymer shell to covalently graft a second monomer layer with precise control over the thickness at the nanometric scale, depending on the photonic parameters. This route can be applied to different nanoobjects and allows an anisotropic surface modification in agreement with the spatial localization of the enhanced electromagnetic field near the nanostructure. This new route opens the door towards the preparation of multifunctional hybrid metal/polymer nanostructures.     

覆膜金属粉末激光烧结过程温度场的数值模拟

目的 对覆膜金属粉末变长线扫描激光地过程的温度场进行研究。方法 对激光源的加热特性。粉末材料的热物性参数及激光烧结动态过程是行研究分析。建立温度场数学模型,应用限元方法进行计算。结果与结论 温度场的数值计算结果与实验测量结果基本吻合。利用模场计算结果可以进行工艺参数优化。     

A mechanism-based multi-scale model for predicting thermo-oxidative degradation in high temperature polymer matrix composites

This paper describes a mechanism-based multi-scale model for life prediction of high temperature polymer matrix composites (HTPMC) under thermo-oxidative aging conditions. The multi-scale model incorporates molecular level damage such as inter-crosslink chain scission in a thermoset polymer due to thermo-oxidative aging of the polymer resin. The degradation of inter-laminar stress depends on remaining inter-crosslink density of thermo-set polymer in fiber/matrix interface region subjected to thermo-oxidative aging environment. The degradation of inter-laminar shear stress of thermo-oxidatively aged unidirectional IM-7/PETI-5 composite specimens at 300 °C was modeled using an in-house test-bed FEA code (NOVA-3D). A micromechanics based viscoelastic cohesive layer model was used to model delamination. The model is fully rate dependent and does not require a pre-assigned traction-separation law. Viscoelastic regularization of the constitutive equations of the cohesive layer used in this model not only mitigates numerical instability, but also enables the analysis to follow load-deflection behavior beyond peak failure load. The model was able to successfully simulate delamination failure in thermo-oxidatively aged unidirectional IM-7/PETI-5 composite, and the model predictions were verified using test data.     

High temperature polyimide containing anthracene moiety and its structure, interface, and nonvolatile memory behavior

A high temperature polyimide bearing anthracene moieties, poly(3,3'-di(9-anthracenemethoxy)-4,4'-biphenylene hexafluoroisopropylidenediphthalimide) (6F-HAB-AM PI) was synthesized. The polymer exhibits excellent thermal stability up to around 410 °C. This polymer is amorphous but orients preferentially in the plane of nanoscale thin films. In device fabrications of its nanoscale thin films with metal top and bottom electrodes, no diffusion of the metal atoms or ions between the polymer and electrodes was found; however, the aluminum bottom electrode had somewhat undergone oxide layer (about 1.2 nm thick) formation at the surface during the post polymer layer formation process, which was confirmed to have no significant influence on the device performance. The polymer thin film exhibited excellent unipolar and bipolar switching behaviors over a very small voltage range, less than ±2 V. Further, the PI films show repeatable writing, reading, and erasing ability with long reliability and high ON/OFF current ratio (up to 10(7)) in air ambient conditions as well as even at temperatures up to 200 °C.     

The use of fast heavy ions to improve thin film adhesion

Fast heavy ions from the Uppsala tandem accelerator were used to irradiate various film/substrate systems such as metal/glass, metal/polymer and metal/metal. Adhesion is in some cases substantially improved by this method. Semiquantitative evaluation by the scratch method was made of the dose dependence of the improvements and also to facilitate comparison with conventional adhesion- promoting treatments. At present, no satisfactory explanation for the effects exists. Copper-coated aluminium was used to demonstrate the importance of the natural oxide layer.It is evident that intense irradiation causes a temperature rise. The film temperature was therefore monitored during irradiation using an IR thermometer. No abnormal heat effects were found although some polymers deteriorated due to the irradiation. For metals the temperature rise is less than 1 °C.     

UV-radiation curing of simultaneous interpenetrating polymer network hydrogels for enhanced heavy metal ion removal

Simultaneous interpenetrating polymer network (IPN) hydrogels have been prepared by UV-initiated polymerization of a mixture of acrylamide (AM) and triethylene glycol divinyl ether (DVE-3). The consumption of each monomer upon UV-irradiation was monitored in situ by real-time infrared (RTIR) spectroscopy. The acrylamide monomer AM was shown to polymerize faster and more extensively than the vinyl ether monomer DVE-3, which was further consumed upon storage of the sample in the dark, due to the living character of the cationic polymerization. The IPN hydrogels were used to remove heavy metal ions from aqueous solution under the non-competitive condition. The effects of pH values of the feed solution and the DVE-3 content in the formulation on the adsorption capacity were investigated. The results indicated that the adsorption capacity of the IPN hydrogels increased with the pH values and DVE-3 content in the formulation. Furthermore, the synergistic complexation of metal ions with two polymer networks in the IPN was found in the adsorption studies. Adsorption kinetics and regeneration studies suggested that the IPN hydrogels could be used as fast-responsive and renewable sorbent materials in heavy metal removing processes.     

Experimental and numerical investigations of the mechanical behavior of half sandwich laminate in the context of blanking

In this study, the complex mechanical behavior of an aluminum/low-density polyethylene (LDPE) half sandwich structure was investigated during the blanking process. Mechanical tests were conducted for the polymer and metal layer and the delamination behavior of the adhesive between the two layers. A new testing device was designed for detecting the delamination under tensile mode. Corresponding finite element models were established for the mechanical tests of the metal layer and the delamination of both layers for inverse parameter identification. Material parameters for Lemaitre-type damage, Drucker-Prager, and cohesive zone models were identified for the metal, polymer, and adhesive, respectively. A finiteelement (FE) model was established for the blanking process of the sandwich structures. The experimental forcedisplacement curves, obtained in the blanking process of the half sandwich sheet, were compared with the predicted results of the FE model. The results showed that the predicted force-displacement curves and the experimental results were in good agreement. Additionally, the correlation between cutting clearance and changes in the forcedisplacement curves was obtained. Three feature values quantitatively described the imperfection of the experimental cutting edge. The effect of punch clearance on these values was studied numerically and experimentally. The results indicated that a smaller clearance generated a better cutting-edge quality. The stress state of the half sandwich structure during blanking was analyzed using the established FE model.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00308-z