轴向正压力作用下新型触觉复合材料电阻机械效应研究

制备了一种纳米级导电炭黑填充热塑性弹性体的触觉敏感复合材料,并在MTS810材料万能试验机上对复合材料的力学性能和电学性能进行了同步测定。主要讨论了不同轴向加载速率对复合体系电阻机械效应的影响。结果表明,在0MPa~2.5MPa压力范围内,复合材料的压力-电阻拟合曲线接近线性;当轴向加载速率从0.25N/s增加到1.0N/s后,材料的压力-电阻拟合曲线的线性度有了一定程度的改善。     

CPP薄膜表面的氟等离子体聚合及其亲水性研究

通过等离子体引发聚合的方法,使三氟氯乙烯(CTFE)在CPP(流延聚丙烯)薄膜表面发生聚合反应.分别对未处理的CPP薄膜和经等离子体聚合处理的CPP薄膜进行质量分析、扫描电镜和能谱表征,证实在CPP薄膜表面生成了含氟聚合物.在一定范围内考察了聚合时间、板极电压和压力对三氟氯乙烯沉积速率的影响,由于等离子体刻蚀作用与聚合反应同时存在,沉积速率与3种过程因素均未呈现线性关系.氟聚合物层使薄膜表面极性减弱,导致表面能中极性分量所占的比例减少,色散分量的比例增加,表面能降低,水和乙二醇在薄膜表面的接触角增大,CPP薄膜的表面亲水性减弱.     

SiC维纤增强钛基复合材料的疲劳裂纹扩展速率

用箔-纤维-箔法制备SiC纤维增强Ti-6Al-4V复合材料,研究复合材料在加载频率f=10Hz、应力比R=0.1、最大应力σmax=300MPa条件下的疲劳裂纹扩展速率(da/dN),并采用扫描电子显微镜对疲劳破坏断口进行观察和分析。结果显示,在该加载条件下,复合材料第Ⅱ阶段疲劳裂纹扩展速率符合高斯函数。断口观察表明,复合材料的基体在裂纹稳态扩展区出现明显的疲劳条带,复合材料的疲劳损伤可以分为纤维断裂、基体开裂和纤维/基体界面脱粘等多种形式。     

加载速率对复合型氢致开裂的影响

通过改变复合型载荷比来改变裂端三轴张力和塑性变形程度，研究了不同加载速率下３０ＣｒＭｎＳｉＡ钢／０．５ｍｏｌ／ＬＨ２ＳＯ４体系的Ｉ型及（Ⅰ＋Ⅱ）复合型氢致开裂抗力，探讨加载速率对氢传输、对裂端氢富集浓度以及对Ｉ型、复合型氢致开裂抗力的影响．     

氮气流量对 ZrN / Zr 薄膜色度特性的影响

采用中频孪生靶磁控溅射技术,在不锈钢和铝基体上沉积出ZrN/Zr薄膜,表征了薄膜的厚度、色度及表面形貌,研究了氮气流量对ZrN/Zr薄膜的沉积速率和色度的影响。结果表明:随着氮气流量的增加,薄膜的沉积速率先降低,后升高,氮气流量在2.5×10-10～3.5×10-10m3/s范围内时对薄膜的沉积速率影响很小;随着氮气流量的变化,薄膜的颜色呈现规律性的变化,在氮气流量2.5×10-10～3.5×10-10m3/s范围内,可以制备出色彩亮丽的仿金薄膜ZrN,且膜层致密。     

LPCVD-Si3N4工艺及性能研究

使用低压化学气相沉积工艺（LPCVD），以三氯硅烷和氨气作为硅源和氮源，在烧结氮化硅表面制备氮化硅薄膜。分别考察了载气、沉积温度以及原料配比等工艺参数对沉积速率的影响，并对薄膜的组成、结构及硬度等性能进行了分析。结果表明，较好的工艺条件是，采用N2或N2＋H2为载气、沉积温度为800℃，NH3／HSiCl3流量比为4，此时薄膜沉积速率可达23．4nm／min，其主要由Si—N组成，并含有部分Si-O，硬度为28650MPa。     

不同拉伸条件下碳／环氧复合材料损伤的声发射特性

为了研究复合材料在动载荷和恒载情况下的损伤机理,在不同加载速度和恒载情况下,对T700／环氧复合材料进行了拉伸损伤声发射试验研究。从其损伤过程和声发射特性发现,在较低速率下,该复合材料断裂强度对拉伸速率变化不够敏感;但随着拉伸速率的增大,基体及界面损伤的高峰出现时间逐渐提前,断裂时损伤越来越不完全;恒载声发射效应反映了复合材料抗蠕变损伤的能力,而其收敛能力的大小反映了复合材料构件历史损伤的严重程度。     

加载热循环对Mg2B2O5w/AZ31B复合材料塑性的影响

对35%(体积分数)的Mg2B2O5w/AZ31复合材料分别在外加应力为7、14、21和42 MPa时进行加载热循环实验,研究其蠕变行为。结果表明:加载热循环分为初始蠕变阶段、稳定蠕变阶段和失稳变形阶段;外加载荷为42 MPa时,热循环由稳定蠕变阶段迅速进入失稳变形阶段;当外加载荷为21 MPa时,应变速率的急剧变化对累积残余应变影响较小;热循环滞后环倾角随外加载荷的增大而减小;Mg2B2O5w/AZ31复合材料的外加载荷越低,应变速率敏感指数越高,而在400℃的高温蠕变虽也呈现超塑性行为,但应变速率比加载热循环大幅下降。在加载热循环过程中,300℃时基体中的平均内应力接近于零,热循环残余应变的产生主要发生在热循环的高温阶段。     

金属薄膜蠕变变形与材料结构的相关性研究

本文采用纳米压入实验方法评价金属薄膜室温蠕变变形行为与材料微观组织结构的关系。金属薄膜分别选取纳米晶体心立方（BCC）金属Mo、纳米晶面心立方（FCC）金属Ni以及非晶CuZr为研究材料,加载速率为0.005,0.05,0.1,0.2 s-1。研究发现BCC-Mo、FCC-Ni以及非晶CuZr蠕变变形均表现出很强的加载应变速率依赖性,究其原因与其主导变形机制相关。BCC-Mo蠕变行为由螺型位错主导的混合位错运动为主,FCC-Ni蠕变变形由晶界发射不全位错主导,非晶CuZr蠕变行为由剪切变形转变区（STZ）主导变行为主。     

高颗粒含量B4C／Al复合材料的高温压缩力学行为

利用Gleeble3500热模拟机对高颗粒含量B4C／A1复合材料进行了温度范围为298～773K,应变率范围为1×10-3-5S^ （-1）的单轴压缩力学行为测试。结果表明：由于高颗粒含量B4C／A1复合材料在动态载荷和静态载荷作用下的破坏方式不同,导致了在高温条件下复合材料的动态强度随温度的下降速率要小于静态强度的下降速率。当温度从室温升高到773K时,复合材料的应变率敏感指数从0．02增加到0．13,该现象表明,该高颗粒含量复合材料的应变率敏感指数是温度的函数。     

Corrosion and biocompatibility of PPy/PEG coating electrodeposited on Ti6Al7Nb alloy

This work aims to improve the corrosion rate of Ti6Al7Nb alloy and to increase its biocompatibility at the same time, obtaining polymer composite films based on polypyrrole/polyethylene glycol (PPy/PEG). The elaboration method was electrodeposition. FT‐IR analysis was performed in order to emphasize the formation of the PPy‐PEG composite film by incorporating PEG into the polymer structure. The paper is focussed on PEG (400 molecular weight) effect on the corrosion in bioliquids (as tested electrochemical bioliquid was chosen Hank's balanced salt solution) and on the biocompatibility properties. The PPy film significantly improves the biocompatibility of the Ti6Al7Nb alloy. The PEG presence in the polymerization solution leads to more stable composite polymer films on the titanium alloy surface with a better corrosion resistance and a more hydrophilic behaviour comparing with the PPy film. The increase of cell viability and proliferation potential as compared to the PPy film is not important.     

新型化学反应法制备SiC/Al2O3复相陶瓷涂层

陶瓷涂层材料以其高硬度、耐腐蚀、耐高温、抗氧化等一系列优点,在航空航天、武器装备、核工业、石油化工等领域具有广阔的应用前景.SiC/Al_2O_3复相陶瓷在常温和高温下都具有较好耐磨性和化学稳定性,是一种极具工程应用前景的复合陶瓷材料.本研究采用优质陶瓷先驱体聚合物PCS,添加惰性填料SiC纳米颗粒和活性填料金属Al粉共同作用,克服了先驱体法制备陶瓷材料中存在较大体积收缩的缺点,在金属基体上制备了单层厚度可达50 μm的致密SiC/Al_2O_3复相陶瓷涂层,复相陶瓷涂层中的SiC来自于先驱体PCS热解转化的SiC和添加的纳米SiC颗粒;其中的Al_2O_3来自于金属Al粉的氧化.该化学反应方法在金属基体上成功地制备出连续、致密的SiC/Al_2O_3复相陶瓷涂层,既简单又方便,表现出极大的应用潜力.     

Effect of rod-like grain on properties and toughening mechanism of 3Y-TZP/Al2O3 ceramics

In-situ rod-like A1203 grain was prepared by adding CAS multiphase additives under the sintering condition of 30 MPa, 1 550℃ and 1 h. The sintering behaviors, microstructure, toughening mechanism and access of Al2O3 ceramics were investigated by SEM, EDS and WDW omnipotent electronic mechanical testing machine, etc, and the crack propagating model of cylindrical crystal/3Y-TZP composite toughening Al2O3 ceramics was established. The results show that the composite additives prompt the anisotropic growth of Al2O3 grain, which strengthens toughening effect of 3Y-TZP in 3Y-TZP/Al2O3 composite ceramics. Moreover, the experimental material density is near to theoretical density, bending strength is 556.35 MPa, and fracture toughness is 6.73 MPa.m1/2. The mechanical properties of the materials are obviously improved.     

Structural and thermophysical properties characterization of continuously reinforced cast Al matrix composite

In this work the process of manufacturing a continuously reinforced cast Al matrix composite and its properties are presented.The described technology permits obtaining a structural material of competitive properties compared to either heat treatable aluminum alloys or polymer composites for several types of applications.The examined thermophysical properties and structural characterization,including material anisotropy,coupled with the results of previous measurements of the mechanical properties of both Al2O3reinforcing filaments and metallic prepregs have proven the high quality of this material and the possibility of its operation under special loading modes and environmental conditions.Microscopic examinations(LM,SEM)were carried out to reveal the range of morphological homogeneity of the microstructure,the anisotropy of the filament band distribution,and simultaneously the adhesive behavior of the metal/fiber interface.The 3D morphology of the chosen microstructure components was revealed by computed tomography.The obtained results indicate that special properties of the examined prepreg materials have been strongly influenced,on the one hand,by the geometry of its internal microstructure,i.e.spatial distribution and volume fraction of the Al2O3 reinforcing filaments and,on the other hand,by a very good compatibility obtained between the individual metal prepreg components.     

Fabrication of aluminum matrix composite reinforced with carbon nanotubes

1.0wt.% carbon nanotube （CNT） reinforced 2024Al matrix composite was fabricated by cold isostatic press and subsequent hot extrusion techniques. The mechanical properties of the composite were measured by a tensile test. Mean-while,the fracture surfaces were examined using field emission scanning electron microscopy. The experimental results show that CNTs are dispersed homogeneously in the composite and that the interfaces of the Al matrix and the CNT bond well. Although the tensile strength and the Young’s modulus of the composite are enhanced markedly,the elongation does not decrease when compared with the matrix material fabricated under the same process. The reasons for the increments may be the extraordinary mechanical properties of CNTs,and the bridging and pulling-out role of CNTs in the Al matrix composite.     

Conducting polyaniline/poly(tetrafluoroethylene) composite films with tunable surface morphology and hydrophilicity

A composite conductive polymer film, polyaniline-coated polytetrafluoroethylene, noted as PANI/PTFE, has been successfully synthesized by a simple chemical oxidation polymerization approach. The observed surface morphology of the PANI/PTFE film confirms that the network structural PTFE film acted as template in the synthesis of the composite film to get PANI@PTFE coaxial-line structure at a relative low oxidant concentration. By regulating the molar ratio of oxidant to monomer, the morphological evolution of the composite film could be controlled, resulting in the tunable hydrophilicity. As a consequence of an optimal combination of the characteristic features of PANI and PTFE, a composite film with excellent mechanical properties, high conductivity, easy processability, adjustable hydrophilicity and reversible conversion between hydrophobicity and hydrophilicity have been obtained.     

Ti/Al过渡层对共掺杂类金刚石薄膜性能的影响

目的研究Ti/Al过渡层对不同溅射电流下的Ti/Al共掺杂DLC薄膜的成分、结构、机械性能和结合力的影响。方法采用线性离子束复合磁控溅射技术在316L基底上沉积含有Ti/Al过渡层的Ti/Al共掺杂DLC薄膜,利用场发射扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)、高分辨透射电镜(HRTEM)及共聚焦激光拉曼光谱仪分析了薄膜的界面形貌及键态结构。采用辉光放电光谱仪对样品成分进行深度分析,纳米压痕仪测量薄膜硬度及弹性模量,划痕测试系统测量膜基结合力,残余应力仪测量薄膜内应力。结果与未添加过渡层相比,添加Ti/Al过渡层对薄膜的结构和机械性能影响较小,且均在溅射电流为2.5 A时有最优的机械性能;然而,溅射电流为2.5 A时,添加过渡层使结合力从54.5 N提高到了67.2 N,提高了19%,残余应力从1.28 GPa降低到了0.25 GPa,降低了80%。结论 Ti/Al过渡层可缓解因DLC薄膜和基体的晶格匹配差异和膨胀系数不同而导致的高界面应力。在薄膜与基底界面,过渡层呈现典型柱状晶结构,可促进膜基界面间的机械互锁,显著改善薄膜与基体之间的结合力而不损伤其机械性能。     

纳米压入技术表征薄膜（涂层）的力学性能

采用纳米压入技术测试薄膜（涂层）的力学性能日益受到关注。测试过程中可自动记录载荷－压深曲线,能够获取薄膜（涂层）的硬度、弹性模量、薄膜（涂层）自身结合强度、膜基界面结合强度、残留应力、屈服强度以及应变硬化率等力学性能数据。本文扼要介绍了纳米压入技术表征薄膜（涂层）力学性能的测试原理。     

聚乳酸-聚吡咯/银多层复合抗菌薄膜的制备与性能表征

目的提高聚乳酸(PLA)薄膜的抗菌性能。方法受到导电高分子材料可以通过静电作用方式起到抗菌作用的启发,利用Fe~(3+)引发吡咯(Py)在PLA薄膜表面发生化学氧化反应,聚合形成抗菌涂层(PPy),成功制备出PLA-PPy多层复合抗菌薄膜。采用等物质的量Ag~+替代Fe~(3+),引发Py在PLA薄膜表面聚合形成双重抗菌涂层(PPy/Ag),成功制备出PLA-PPy/Ag多层复合抗菌薄膜,并探讨了不同氧化剂和Py浓度对多层复合薄膜结构和性能的影响。结果当PLA薄膜表面积为72 cm~2,水溶液体积为40 mL,Fe Cl_3·6H_2O的浓度为0.047 mol/L,Py的浓度为0.223 mol/L时,PLA-PPy多层复合薄膜的表面PPy层结构致密,拉伸强度(40.1 MPa)和断裂伸长率(24.9%)分别降低了7.6%和12.6%,热稳定性得到较为明显的提高。此外,PLA-PPy/Ag与PLA-PPy多层复合薄膜表现出相似的力学性能和热稳定性。更为重要的是,相比于PLA-PPy多层复合薄膜,PLA-PPy/Ag多层复合薄膜表现出更为优异的抗菌特性,大肠杆菌的菌落总数降低至2.9×10~6 CFU/cm~2,相比于纯PLA薄膜(4.8×10~(10) CFU/cm~2),降低了超过4个数量级。结论相比于完全采用成本较高的纳米银离子负载抗菌方式来说,较低成本的双重抗菌涂层(PPy/Ag)将会在PLA活性包装领域具有一定的研究意义。     

内氧化Al2O3／Cu—Cr复合材料工艺与性能的研究

通过对Al2 O3 Cu Cr复合材料内氧化粉末冶金工艺的优选 ,探讨了添加合金元素Cr对复合材料性能的影响。研究表明 ,弥散分布的Al2 O3 硬颗粒对基体具有明显的强化作用 ;加入适量的Cr所产生的沉淀强化作用进一步提高了材料的力学性能。实验表明 :Al2 O3 Cu Cr复合材料经过 10 0 0℃× 1h固溶处理 ,30 0℃× 2h时效 ,硬度达到 144HV ,比电导率为 6 6 7%IACS。根据实验结果 ,分析了弥散强化和沉淀强化共同作用下材料性能变化的趋势