热爆反应制备原位颗粒增强镁基复合材料

采用Mg-TiO2-B2O3体系热爆方法制备了原位颗粒增强镁基复合材料，并对材料进行了热力学、DTA、XRD和SEM分析。结果表明：在Mg-TiO2-B2O3体系中镁的加入量小于70％（质量分数）的情况下，体系的热爆反应可以在镁液的冶炼温度自发进行，同时可原位合成MgO和TiB2颗粒。5％Mg-TiO2-B2O3体系制备的镁基复合材料的抗拉强度和布氏硬度分别比基体提高了约26％和32％。     

包覆镍的碳纳米管增强AZ91镁基复合材料的显微组织与力学性能

用搅拌铸造技术制备了化学包覆镍的碳纳米管增强AZ91镁基复合材料;研究了碳纳米管对其显微组织和力学性能的影响,并利用扫描电子显微镜和能谱仪对复合材料断口形貌进行了观察和分析。结果表明:化学包覆镍碳纳米管明显细化了基体合金的晶粒,对AZ91镁合金有较的增强效果;与基体合金相比,加入适当碳纳米管时复合材料的抗拉强度、弹性模量、显微硬度均显著增加,伸长率和抗拉强度最多可分别提高90.44%和37.5%,但是碳纳米管加入量过多会导致其产生偏聚,使复合材料力学性能下降。     

碳纳米管增强镁基复合材料的组织与力学性能

在Mg-1.3Mn-1.0Ce-4.0Zn合金熔体中加入质量分数为0~1.5%的碳纳米管(CNTs),采用搅拌铸造法制备了碳纳米管增强镁基复合材料,研究了复合材料的组织和力学性能,并探讨了复合材料的强韧化机制。结果表明:CNTs能细化基体合金的晶粒尺寸,改变晶粒形貌及第二相的分布特征;随着CNTs添加量增大,复合材料的室温强度、断口伸长率和硬度均呈先增大后减小的趋势;当CNTs的质量分数为0.5%时,室温强度、断后伸长率和硬度最高,分别为212.2 MPa,21.1%和55.0HBW,较基体合金的分别增加了8.5%,37.5%和10%;复合材料的强韧化机制包括增强相强化、第二相强化和细晶强化,而晶粒细化、CNTs的润滑作用及对裂纹的阻碍作用是复合材料塑性提高的主要原因。     

二维碳纤维/镁基复合材料的力学和热膨胀性能

采用挤压铸造法制备出二维碳纤维织物增强镁基复合材料,并对其基本性能进行了研究.结果表明:加入二维织物能有效提高复合材料的弯曲性能,使抗弯强度达到414 MPa,弹性模量达到59.65 GPa,并且使复合材料的力学性能具有经向和纬向对称性;碳纤维织物的加入降低了复合材料的热膨胀系数,该材料经过热处理后,在20～200℃内平均热膨胀系数仅为5.59×10-6/℃,明显低于基体镁合金.     

包覆镍CNTs/AM60复合材料铸态显微组织与力学性能

采用机械搅拌铸造法制备了包覆镍碳纳米管(CNTs)/AM60复合材料,研究了包覆镍CNTs加入量对铸态复合材料力学性能的影响规律,并用扫描电子显微镜观察了复合材料的拉伸断口形貌以及显微组织。结果表明:复合材料显微组织为等轴晶,包覆镍的CNTs主要分布在-αMg共晶相内和晶界处,不仅起到细化晶粒的作用,而且还起到搭接晶粒和强化晶界的作用;复合材料的力学性能随CNTs加入量的增多呈现先增大后减小的趋势,当其质量分数为1%时,抗拉强度、显微硬度、伸长率同时达到最大,比AM60镁合金分别提高了46.23%,41.82%,74.52%,弹性模量在其质量分数为1.2%时达到最大。     

纤维含量对纤维增强复合材料影响的研究

用粉末治金法制备了钢纤维增强的Sn-Cu-Fe-WC基复合材料,研究了纤维含量对复合材料密度、抗拉强度、单位体积吸收能量值、断裂伸长率、弹性模量和硬度的影响。结果表明:随着纤维含量的增加,复合材料的其塑韧性略有降低,弹性模量基本保持不变。抗拉强度和硬度却随着纤维含量的增加而增大,在纤维含量的15%时抗拉强度达到最大值,随后抗拉强度和硬度又逐渐减小。可见:纤维含量太低不能充分发挥纤维在复合材料中增强效果,反而成为多余夹杂甚至成为缺陷源。但含量过高工艺上又不易实现,最佳的纤维含量应该为15%。     

纳米碳管增强纯铝基复合材料的制备及性能

将采用电孤放电法制备的未纯化和纯化的CNTs作为增强体与纯铝粉混合，用粉末冶金法成功制备了1％纳米碳管增强铝基复合材料。力学性能测试表明，未经纯化的纳米碳管对基体增强效果甚小；而纯化的纳米碳管增强效果较为明显，1％纯化纳米碳管增强铝基复合材料力学性能高于10％微米碳化硅强化铝基复合材料，证实添加的纯化纳米碳管对铝基体有良好的强化效果。     

碳纳米管/环氧树脂复合材料研究

将碳纳米管加入到环氧树脂中，经超声分散处理制得复合材料。研究了碳纳米管的加入量与分散程度对材料抗拉强度的影响。研究表明：碳纳米管的加入量小于3％时可有效提高复合材料的抗拉强度，加入量为1．7％，抗拉强度达到最高值52．38MPa，比纯环氧树脂(26．40MPa)提高98．4％。     

真空热压烧结SiC_p/Al复合材料的界面元素扩散及增强断裂机理

采用真空热压粉末冶金烧结工艺制备了含SiC颗粒体积分数分别为 5 %、15 %和 2 5 %的SiC颗粒增强铝基复合材料 ,结合其力学性能、扫描电镜和界面微区能谱分析结果 ,分析了SiC/Al复合材料的真空烧结过程中的界面现象 ,以及材料增强和断裂机理。结果表明 ,真空烧结过程中出现了界面反应 ,改善了界面结合强度 ,断裂破坏主要在基体上进行。随着SiC粒子体积分数的增加 ,SiCp/Al复合材料的抗拉强度增加 ,弹性模量显著增加 ,延伸率降低 ,材料脆性增加。     

DSC在自生TiB2颗粒增强铝基复合材料制备中的应用

采用差分扫描热分析(DSC)方法，测定了TiB2／Al-12VoSi的复合过程，并以热分析数据为依据，制备了TiB2／Al-12%Si复合材料，通过X射线衍射(XRD)分析了复合材料的增强相，考察了微观组织和力学性能的关系。结果表明：采用直接反应合成法制备该复合材料的最佳温度在830～860℃；半固态搅拌技术可使增强相在基体中的分布更加均匀；颗粒增强复合材料的力学性能有较大改善，抗拉强度由166MPa提高到184MPa，在热处理后达到336MPa，弹性模量由36．5GPa提高到43．9GPa，但伸长率从12％下降到了2．3％；利用DSC来制订颗粒增强铝基复合材料制备工艺是合理可行的。     

聚氨酯/碳纳米管复合材料的摩擦性能

采用溶液共混法制备聚氨酯/碳纳米管复合材料,探讨碳纳米管含量和超声分散时间对聚氨酯/碳纳米管复合材料摩擦性能的影响。结果表明:随着碳纳米管含量的增加,聚氨酯/碳纳米管复合材料的摩擦因数逐渐降低,随着载荷的增大,摩擦因数有所减小;超声分散时间对聚氨酯/碳纳米管复合材料摩擦性能影响不大;碳纳米管具有较好的润滑性质,可以降低聚氨酯/碳纳米管复合材料的摩擦因数,改善聚氨酯的摩擦性能。     

碳纳米管直径对丁腈橡胶复合材料性能影响的分子模拟

利用分子动力学模拟研究碳纳米管(CNTs)直径改变时对丁腈橡胶(NBR)基体力学及摩擦学性能的影响。采用恒应变法考察不同复合材料模型的力学性能，结果表明复合材料力学性能随着NBR基体中CNTs直径增大呈现先增加后减小的趋势。剪切模拟结果表明，剪切后复合材料基体中分子链发生了不同程度的断裂，出现了聚合物分子链向摩擦界面聚集的现象，其中较大直径CNTs增强NBR复合材料中分子链相对完整连续，摩擦学性能改善效果更好。较大直径CNTs对NBR基体具有显著的增强效果，限制了NBR分子链的活动能力，更多的分子链聚集在CNTs周围，复合材料体系致密性及稳定性提高，从而改善了CNTs/NBR复合材料力学及摩擦学性能。其中直径(6,6)CNTs增强NBR复合材料具有更高的剪切模量，力学性能优异，表现出了更好的摩擦磨损性能。     

Preparation and tribological properties of the carbon nanotubes–Ni–P composite coating

A method to prepare the carbon nanotubes (CNTs)–Ni–P composite coating with different mass content of CNTs on the surface of 45^# steel by electroless plating was proposed. The transmission electron microscopy (TEM) and the scanning electron microscopy (SEM) were used to observe the appearance of the as-prepared CNTs and the CNTs–Ni–P composite coating, and then the roughness of the coating surface was also analyzed by atomic force microscopy (AFM). Furthermore, the wear and friction behavior of the CNTs–Ni–P composite coating were investigated under oil-lubricated condition, Due to the self-lubrication property and the unique antifriction structure, CNTs can greatly improve the wear resistance of the CNTs–Ni–P composite coating, where the wear resistance of the CNTs–Ni–P composite coating is optimized with the intermediate mass content of 2 kg/m³ CNTs.     

碳管分散程度对环氧树脂复合材料的摩擦磨损性能影响

采用浇铸法,制备多壁碳纳米管(MWNTs)/环氧树脂(EP)复合材料,利用M-200摩擦磨损试验机研究了MWNTs含量、分散时间及方式对环氧复合材料摩擦磨损性能影响,通过SEM、TEM分析试样磨损形貌表面、MWNTs分散程度。结果表明:碳纳米管添加量1.5%(质量分数)时,MWNTs/EP复合材料比环氧树脂摩擦因数降低17.8%,磨耗率降低91.7%;加入碳纳米管降低了复合材料粘着磨损与疲劳剥落;延长超声波时间及采用高功率超声波仪器能够有效提高碳纳米管分散程度,提高复合材料摩擦磨损性能。     

Ag基碳纳米管(碳纳米纤维)复合电镀

为获得电接触性能优越的复合电镀层，选用碳纳米管及碳纳米纤维作为增强相物质，在优化选择的镀液体系中，利用超声振荡辅助复合电镀制备Ag基碳纳米管及碳纳米纤维复合电镀层。通过扫描电子显微镜（SEM）和透射电子显微镜（TEM）进行观察，证明碳纳米管及碳纳米纤维能够均匀分散到Ag基体中并实现良好结合，其中，Ag更在碳纳米管表面外延生长，形成了有效的界面结合。     

碳纳米管/聚乳酸复合材料的制备与性能

用熔融共混的方法制备了碳纳米管(CNTs)/聚乳酸(PLA)复合材料,观察了其球晶形貌和断面形貌,并研究了不同配比的CNTs/PLA复合材料的结晶性能和水解性能。结果表明:CNTs可以作为异相成核剂提高PLA的结晶速率和结晶度,CNTs质量分数为1%时,复合材料的结晶度达到44.9%,CNTs能够在基体中均匀分散;CNTs质量分数小于1%时,断面呈中间层破形貌;随CNTs含量增多,复合材料的球晶直径变大;CNTs能降低PLA的水解速率。     

Tribological properties of carbon-nanotube-reinforced copper composites

Tribological properties of carbon-nanotube-reinforced copper composites were investigated using a pin-on-disk test rig under dry conditions. The composites containing 4–16 vol% carbon nanotubes (CNTs) were fabricated by a powder-metallurgy technique. The tests were carried out at normal loads between 10 and 50 N, and the effect of volume fraction of CNTs on tribological behavior of the composites was examined. The composites revealed a low coefficient of friction compared with the copper matrix alloy. Due to the effects of the reinforcement and reduced friction, the wear rate of the composites decreased with increasing volume fraction of CNTs at low and intermediate loads. The composites with a high volume fraction of CNTs exhibited high porosity and their wear resistance decreased under high-load conditions.     

Modeling of interfacial friction damping of carbon nanotube-based nanocomposites

Carbon nanotube-based composite is becoming increasingly popular and offers great potential for highly demanding practical high strength and high damping applications. The excellent damping capacity of CNTs is primarily due to the interfacial friction between carbon nanotubes and polymer resins and the extremely large interfacial surface area over a given specific mass (specific area). In this paper, damping characteristics of carbon nanotube-based composites have been investigated, with an objective of developing an effective and accurate analytical model, which can be used as a design tool for the damping design of such materials. Based on the interfacial slips between the resin and nanotubes and between the nanotubes themselves, a micro stick-slip damping model has been developed. Such a physically derived model is believed to be appropriate and representative of the actual complex damping mechanism of the material system. The model, developed for the first time, is analytical and relates explicitly the material properties of the resin and nanotubes and the processing parameters to the overall material damping loss factor and hence it offers the possibility for material engineers to possibly optimize the damping for required applications. Due to the nonlinear force–displacement relationship derived under the micro stick-slip, a harmonic linearization method, the Describing Function method, has been employed to analyse its vibration characteristics and to derive the required damping loss factors. From the analytical formula, it can be seen that the damping loss factor of the material system depends on the individual material properties of the resin and the nanotubes, structural deformation, nanotube volume fraction and the critical shear stresses at which interfacial slips take place. By taking careful considerations of these design parameters, optimized carbon nanotube-based composites for advanced damping applications can be developed.Extensive numerical simulations have been carried out to establish the practical applicability of the proposed analytical model. Based on realistic material properties of carbon nanotubes and polymer resins, damping characteristics have been predicted which compare well with existing results from open literature. The results have shown that for a volume fraction as small as 1%, a damping loss factor as high as 20% can be achieved which is adequate for most practical applications. The model has been further developed to deal with bending vibrations where different parts of the material are subject to different vibration strain levels. A practical case of cantilevered beam vibration has been employed to demonstrate the practical application of the proposed model.     

SiCp/Al复合材料镀金工艺研究

SiCp/Al复合材料导电性差、膨胀系数低,尤其是不具备钎焊能力。为了满足封装壳体的良好钎焊性能,必须对其表面进行镀金改性处理。文中针对SiC体积分数高达60%以上的SiCp/Al复合材料进行镀金工艺研究,主要目的是解决镀金层与基材之间的结合力难题。通过工艺试验,采用工艺分步实施化学镀镍、热处理、电镀镍、电镀金步骤,得到的镀层表面光滑平整,没有明显的结瘤和夹杂,与基材的结合力强。该工艺作为SiCp/Al可焊性表面处理技术之一,对于其他铝基复合材料表面处理具有重要的参考价值。