粉末冶金在CNTs增强金属基复合材料中的应用

碳纳米管(CNTs)具有优异的力学和物理化学性能,是理想的复合材料增强体之一。综述了近几年国内外通过粉末冶金方法进行CNTs增强金属基复合材料制备的应用,阐述了用粉末冶金法制备CNTs/金属基复合粉末和块体材料的进展,最后对其应用前景进行了展望。     

粉末冶金CNTs/Cu复合材料的显微组织与力学性能

对碳纳米管(carbon nanotubes,CNTs)进行化学镀铜,然后采用粉末冶金法制备CNTs含量(质量分数,下同)为0~4%的CNTs增强铜基复合材料(CNTs/Cu)。研究CNTs含量、成形压力以及后续处理工艺对CNTs/Cu复合材料组织及力学性能的影响。结果表明:化学镀铜后的CNTs,CNTs与铜界面结合良好;与Cu粉混合球磨后,镀铜的CNTs嵌入铜基体中,其管状结构没有遭到明显破坏;随CNTs含量增加,CNTs/Cu复合材料的硬度提高,抗拉强度先增大后减小,CNTs的最佳含量(质量分数)为1%;复合粉体的最佳成形压力为1 400 MPa;异步冷轧比复压更有利于提高复合材料的抗拉强度与显微硬度;经过异步冷轧处理的1%CNTs/Cu复合材料的抗拉强度达350.05 MPa,比纯铜提高1倍,显微硬度HV为196.2,比纯铜提高32.03%。     

不同纳米相增强铜基复合材料的性能

采用粉末冶金法,制备纳米SiO2颗粒(n-SiO2)、纳米SiC晶须(n-SiCw)和碳纳米管(CNTs)3种不同形态纳米相增强铜基复合材料,通过光学显微镜(OM)、扫描电镜(SEM)和球/盘式摩擦磨损试验机等测试手段研究纳米添加相对铜基复合材料显微组织、物理性能和摩擦学性能的影响。结果表明,纳米相可以显著提高铜基复合材料的硬度,其中n-SiCw的增强效果优于n-SiO2和CNTs;CNTs/Cu的减摩耐磨效果优于SiO2/Cu和SiCw/Cu;0.75%-CNTs/Cu(质量分数)复合材料具有高的硬度、优良的减摩耐磨性能,是综合性能最佳的复合材料。     

碳纳米管和氧化铝颗粒协同增强铜基复合材料的制备与性能研究

本文首先利用碱式高锰酸钾对纯化后的CNTs进行改性处理,然后用分子水平法制得前驱体CNTs/Cu复合粉末,最后用内氧化方法,结合放电等离子烧结获得CNTs、Al_2O_3/Cu复合材料。结果表明:CNTs、Al_2O_3/Cu复合材料的维氏硬度(136)和抗拉强度(226 MPa)均优于两个增强相单独作用的铜基材料;材料的断后伸长率超过纯铜(40.1%),达到43.6%,表现出非常好的塑性;CNTs和Al_2O_3两个增强相对铜基材料导电率起到了协同增强作用,达到了1+12的效果。     

微波烧结温度对CNTs/Cu复合材料结构和性能的影响

结合液相混合方法、微波烧结技术和冷轧技术制备碳纳米管增强铜基（carbon nanotubes reinforced copper-matrix,CNTs/Cu）复合材料,研究不同烧结温度对于CNTs/Cu复合材料微观形貌、力学性能及物理性能的影响。结果表明,采用液相混合法制备出粒径为200~500 nm、碳纳米管质量分数为0.5%的CNTs/Cu复合粉体,碳纳米管均匀分散在铜颗粒中,并与之形成良好结合界面。CNTs/Cu复合材料的相对密度、硬度、电导率随着烧结温度的升高先增大后减小,在烧结温度为1000℃时达到最佳。制备的碳纳米管质量分数为0.5%的CNTs/Cu复合材料组织均匀、孔隙数量及尺寸较少,相对密度为95.79%,硬度为HV 80.9,电导率为81.8% IACS。经冷轧处理后,CNTs/Cu复合材料拉伸强度达到218 MPa,延伸率保持37.75%。由此可见,微波烧结技术是一种制备高性能CNTs/Cu复合材料的理想方法。     

微波辅助化学镀铜制备CNTs/Cu复合粉体

碳纳米管(CNTs)表面化学镀是粉末冶金法制备CNTs增强金属基复合材料的重要预处理过程,也是提高其与金属基体界面结合强度的重要途径。本文通过微波辅助化学镀铜法制备CNTs-Cu复合粉体,并对该方法的反应速率和反应效果进行研究。通过碘量法测试镀液中Cu~(2+)的浓度表征反应速率,XRD检测复合粉体中的物相组成,SEM和TEM分别观察复合粉体的微观形貌和结构。实验发现微波辅助化学镀的反应速率是常规化学镀方法的12倍,XRD和电子显微镜分析表明,微波辅助化学镀铜的效果良好,Cu颗粒还原较为充分,CNTs表面附着大量纳米铜颗粒,铜颗粒与CNTs结合紧密,且分布均匀。     

粉末冶金技术制备钼基复合材料研究进展

概述了粉末冶金技术制备钼基复合材料的研究进展,介绍了钼基复合材料常用的增强体以及增强体对钼基复合材料性能的影响。重点阐述了制备钼基复合材料的工艺方法,包括钼粉制备工艺,复合粉末制备方法,粉末成形及致密化技术等三个方面,分析了不同工艺方法的优缺点及其对钼基复合材料制备的影响。总结了粉末冶金技术制备钼基复合材料目前存在的一些问题,并对其发展方向进行了展望。     

SiCp/Cu复合材料的SPS烧结及组织性能

以化学镀Cu包覆SiC粉末和高压氢还原法制备的Ni包SiC复合粉末为原料,用放电等离子体烧结法制备了SiCp/Cu复合材料.分析了增强相含量和烧结温度对致密化的影响,比较了非包覆粉末和包覆粉末制备的复合材料的界面结合状况.然后对SiCp/Cu复合材料的热膨胀行为和力学性能进行了研究.结果表明:包覆粉末能够促进材料的致密化并且能获得良好的界面结合,所得SiCp/Cu复合材料的致密度达96.7%,抗压强度达1061 MPa.SiCp/Cu复合材料的热膨胀系数介于7.5×10-6～11.4×10-6·K-1之间,并且随SiC体积分数的增加而降低.材料在热循环过程中出现热滞现象,热滞现象受增强相的含量及界面结合状况的影响.     

RGO/Cu复合材料的制备和力学性能研究

通过硝酸铜、热甘氨酸和氧化石墨烯的一步热反应,成功合成了RGO/Cu复合粉末,对复合粉末进行放电等离子烧结制备RGO/Cu复合材料。结果表明,RGO片层中均匀分布着Cu纳米粒子,RGO/Cu复合粉中RGO与Cu通过氧协调C-O-Cu键产生强相互作用,近而增强RGO/Cu界面结合强度,并且在烧结RGO/Cu复合材料中得到保持。相对于纯Cu,0.6%RGO的RGO/Cu复合材料的屈服强度增加了75.8%,抗拉强度增加了47.7%,同时保持了良好的伸长率(29%)。     

碳纳米管的纯化研究进展

碳纳米管(Canbon nanotubes,CNTs)是粉末冶金铜基、铝基、镁基等复合材料的理想增强体之一。但是,由于其制备方法(电弧放电法、激光蒸发法、碳氢化合物催化热解法、电解热合成法、化学气相沉积法等)不可避免产生的杂质(炭质、无定形碳、催化剂颗粒等)影响了其优越性能的充分发挥和实际应用。因此,碳纳米管的纯化成为制备增强复合材料必须优先解决的关键问题。本文简述了CNTs物理纯化方法和化学纯化方法,并将微波液相纯化法和微波气相纯化法这两种新型的纯化方法进行了详细对比,展望了CNTs纯化的发展趋势。     

Multiscale Nonlinear Framework for the Long-Term Behavior of Layered Composite Structures

This paper presents an integrated micromechanical–structural framework for local–global nonlinear and time-dependent analysis of fiber reinforced polymer composite materials and structures. The proposed modeling approach involves nested multiscale micromodels for unidirectional and continuous filament mat (CFM) layers. In addition, a sublaminate model is used to provide a three-dimensional (3D) effective anisotropic and continuum response to represent the nonlinear viscoelastic behavior of a through-thickness periodical multilayered material system. The 3D multiscale material framework is integrated with a displacement-based finite-element code to perform structural analyses. The time-dependent responses in the unidirectional and CFM layers are exclusively attributed to their matrix constituents. The Schapery nonlinear viscoelastic model is used with a newly developed recursive–iterative integration method applied for the polymeric matrix. The fiber medium is linear and transversely isotropic. The in situ long-term response of the matrix constituents is calibrated and verified using long-term creep coupon tests. Good prediction ability is shown by the proposed framework for the overall viscoelastic behavior of the layered material. Material and geometric nonlinearities of I-shape thick composite columns, having vinylester resin reinforced with E-glass unidirectional (roving) and CFM layers, are studied to illustrate the capability of the multiscale material-structural framework. Nonlinear elastic behavior and creep collapse analyses of the I-shape column are performed. The recursive–iterative and stress correction algorithms, which are implemented and executed simultaneously at each material scale, enhance equilibrium and avoid misleading convergent states.     

Composite Material Behavior Using a Homogenization Double Scale Method

In this paper, we present a two-scale numerical method in which structures made up of composite materials are simulated. The method proposed lies within the context of homogenization theory and assumes the periodicity of the internal structure of the material. The problem is divided into two scales of different orders of magnitude: A macroscopic scale in which the body and structure of the composite material is simulated, and a microscopic scale in which an elemental volume called a “cell” simulates the material. In this work, the homogenized strain tensor is related to the transformation of the periodicity vectors. The problem of composite materials is posed as a coupled, two-scale problem, in which the constitutive equation of the composite material becomes the solution of the boundary-value problem in the cell domain. Solving various examples found in the bibliography on this subject demonstrates the validity of the method.     

Ballistic Impact of Braided Composites with a Soft Projectile

Impact tests using a soft gelatin projectile were performed to identify failure modes that occur at high strain energy density during impact loading. Failure modes were identified for aluminum plates and for composites plates and half-rings made from triaxial carbon fiber braid having a 0/±60° architecture. For aluminum plates, a large hole formed as a result of crack propagation from the initiation site at the center of the plate. For composite plates, fiber tensile failure occurred in the back ply at the center of the plate. Cracks then propagated from this site along the ±60° fiber directions until triangular flaps opened to form a hole. For composite half-rings fabricated with 0° fibers aligned circumferentially, fiber tensile failure also occurred in the back ply. Cracks first propagated from this site perpendicular the 0° fibers. The cracks then turned to follow the ±60° fibers and 0° fibers until rectangular flaps opened to form a hole. Damage in the composites was localized near the impact site, while cracks in the aluminum extended to the boundaries.     

轿车空调器用特种复合铝散热片材料研制

研究了复合铝散热片材料的选择及其最佳复合工艺参数。着重探讨了钎焊料Ａ１－１０％Ｓｉ合金经过特殊工艺处理后可压延变形的工艺条件。     

Flight Mechanics Analysis of a Motorized Trike with Composite Wing

In this work, a mathematical model to study the dynamic behavior of a trike ultralight aircraft is developed. This is done because, to the best of the writers’ knowledge, no specific theories are available for powered hang gliders. To do that, in order to take into account the engine thrust, the necessary changes have been made on models developed for hang gliders. The trike, which is a particular case of powered hang glider, is modeled as a compound system made of a wing and an undercarriage. The case of rigid wing, made of composite materials, is considered in the present work. Equilibrium governing equations are written, the trim conditions are evaluated, and the fixed control dynamic stability is investigated for both longitudinal and lateral motion. After that a modified wing configuration, with two additional vertical fins, is investigated and compared. The dynamic response to pilot controls is evaluated to complete the analysis.     

MoDTP与MoDTC的合成与复配

叙述了ＭｏＤＴＰ、ＭｏＤＴＣ的合成方法以及它们与ＺＤＴＰ等的复配物。     

Introduction to Ceramic Matrix Composites in Aerospace Applications

A review of ceramic matrix composites is presented as related to their type, use, and fabrication. Ceramic composites have the potential for high fracture toughness, resistance to catastrophic failure, high strength, low density, low thermal expansion, and high temperature capability and oxidation resistance. For continued development, there are a number of key technical needs including new refractory matrices, new stable fibers, and inert coatings for flbers, as well as affordable techniques which produce the desired composite properties and accomplish complex shape capability. A better materials understanding is necessary, including fiber∕matrix interaction, and mechanics∕structure∕property relationships. Finally, technologies for transition to practice are required, including advanced materials characterization, component design methodology, large scale fabrication, attachment techniques, and nondestructive evaluation. While these composites are in the research and development stage, they offer the structural engineer excellent rigidity, high strength‐to‐weight ratio, high temperature capability and a noncatastrophic failure mode. Potential applications include turbine and internal combustion engines, aerospace structures, and high temperature leading edges and skins. A current application is the use of SiC whisker reinforced Al2O3 matrix composites as cutting tools. Significantly increased cutting speeds, improved interrupted cut performance and increased tool life are found.     

颗粒增强复合材料超塑性中颗粒作用的研究

本文介绍了颗粒增强复合材料超塑必事颗粒的作用；与基体材料相比超塑行为被改变；有利于形核及阻碍晶粒长大；可省去固溶与过时效处理工序。     

复合钢管技术的应用

本文简要介绍了复合钢管在各技术领域的应用，详细叙述了复合钢管的生产工艺，对复合钢管的研究与开发具有一定的指导意义。