纤维增强铝基复合材料的发展现状

从纤维增强铝基复合材料组成的角度出发,对该材料的发展现状进行了综述。首先简要介绍了常用纤维增强体的制备方法和性能特点,随后概述了纤维增强铝基复合材料的主要制造方法以及各种常见纤维增强复合材料的性能特点和应用现状,最后讨论了目前存在的问题及发展趋势。     

纤维增强铝基复合材料的发展现状

从纤维增强铝基复合材料组成的角度出发，对该材料的发展现状进行了综述。首先简要介绍了常用纤维增强体的制备方法和性能特点，随后概述了纤维增强铝基复合材料的主要制造方法以及各种常见纤维增强复合材料的性能特点和应用现状，最后讨论了目前存在的问题及发展趋势。     

纤维增强金属基复合材料耐磨机制的研究

根据纤维增强金属基复合材料的结构特点，研究了界面在复合材料磨损过程中的作用，磨损时，复合材料的界面可消耗纹扩展能量，阻滞裂纹扩展，氧化铝短纤维增强硅合金合材料具有优异的耐磨性；基体中的合金元素有利于形成良好的界面，改善复合材料的耐磨性。     

纤维增强金属基复合材料的应力集中及力学性能

本文提出了一种多裂纹模型，用此模型可以分析复合材料中的应力集中，界面脱粘、基体屈服及裂纹间交互作用，分析结果表明，在纤维中存在着较高的应力集中，基体屈服及反应层中裂纹密度增加都促进应力集中，而界面脱粘则使应力急中松弛，对于涂ＳｉＣ涂层的Ｃ／Ａｌ复合材料，最佳界面结合强度在１００￣３００ＭＰａ之间。     

纤维增强钛基复合材料研究新进展

用强度超过4500MPa的SiC纤维增强常规钛合金所制成的复合材料(TMC)，具有比常规钛合金更高的比强度、比刚度，可满足未来航空航天所需可耐更高温度、更高负载的要求，尤其适合于新一代航空涡轮发动机对高温机械性能的追求。本文综述了美、英、法、德各国在SiC纤维增强钛基复合材料研究方面的现状和取得的成果，已有的研究结果表明，该材料在基础研究、制备研究、应用研究等方面都取得了长足的进步，尤其是制造成本大幅度地降低。直接推动了纤维增强钛基复合材料应用的步伐。     

纤维增强TiAl基复合材料的研究

介绍了纤维增强TiAl基复合材料在制备、界面和力学性能等方面的研究和进展。指出纤维增强TiAl基复合材料是发挥TiAl基合金潜力的一个重要方面。同时,也讨论了纤维增加TiAl基复合材料所面临的一些问题。     

等离子喷镀制造纤维增强钛基复合材料

连续纤维增强的钛复合材料是航空发动机压气机部件很有吸引力的材料,然而,它们的制造仍然是材料科学和工程的一个复杂课题．钛基复合材料（TMC）的应用使航空发动机压气机的设计从惯用的盘和燕尾叶片改为TMC叶状环．这种叶状环设计利用复合材料的纵向强度来传输高的圆周应力,并保持足够的横向强度来传输经向应力．制作的示范叶状环部件,预计减重达到70％;还用T14C制造了诸如致动器和压杆．所有TMC制造方法都要求连续的S江纤维和钛合金基体以正确的纤维取向和体积分数精心排列,以获得最佳的力学性能．在制备未加工的TMC预型坯过…     

单向纤维增强铝复合材料的基体合金化

为了得到高性能的复合材料，选择适当的基体合金是很有必要的。本文研究了基体合金成分对复合材料界面和性能的影响。结果表明，工业铝合金并非理想的复合材料基体，而含有能稳定界面结构的合金元素同时又具有单相显微组织和良好延性的基体可使单向纤维增强铝复合材料获得优良的机械性能，并使之稳定。     

NDT of polymer materials using lock-in thermography with water-coupled ultrasonic excitation

We present an NDT method that uses lock-in thermography with ultrasonic heating. The acoustical damping causes the mechanical energy to be converted to thermal energy. In the defective regions the damping is stronger resulting in higher temperature generation. Thus the heating is selective to defects and gives good defect detectability. Because defects also affect the heat conduction, the method gives combined information of the change of the mechanical and thermal properties of the sample due to defects. The ultrasonic excitation is amplitude modulated and the magnitude and the phase of the temperature are measured by infrared camera and software lock-in detection. The applicability of the method was proved with several polymer and composite samples having delaminations, impact damages, voids, and inclusions.     

Wear and transfer characteristics of carbon fiber reinforced polymer composites under water lubrication

The tribological characteristics of carbon fiber reinforced polymer composites under distilled-water-lubricated-sliding and dry-sliding against stainless steel were comparatively investigated. Scanning electron microscopy (SEM) was utilized to examine composite microstructures and modes of failure. The typical chemical states of elements of the transfer film on the stainless steel were examined with X-ray photoelectron spectroscopy (XPS). Wear testing and SEM analysis show that all the composites hold the lowered friction coefficient and show much better wear resistance under water lubricated sliding against stainless steel than those under dry sliding. The wear of composites is characterized by plastic deformation, scuffing, micro cracking, and spalling under both dry-sliding and water lubricated conditions. Plastic deformation, scuffing, micro cracking, and spalling, however, are significantly abated under water-lubricated condition. XPS analysis conforms that none of the materials produces transfer films on the stainless steel counterface with the type familiar from dry sliding, and the transfer of composites onto the counterpart ring surface is significantly hindered while the oxidation of the stainless steel is speeded under water lubrication. The composites hinder transfer onto the steel surface and the boundary lubricating action of water accounts for the much smaller wear rate under water lubrication compared with that under dry sliding. The easier transfer of the composite onto the counterpart steel surface accounts for the larger wear rate of the polymer composite under dry sliding.     

CFRP复合材料孔隙几何形貌定量分析与研究

利用超声衰减法检测复合材料孔隙率得到了广泛应用,但该方法的理论分析与实测结果只适用于特定频率或特定孔隙率范围。原因之一是理论模型中引入的孔隙几何形貌假设与实际情况不符。采用热压成型法制备了孔隙率为0.03%～4.96%的碳纤维增强树脂（CFRP）试样。采用金相组织观察和定量统计分析方法,研究CFRP复合材料的孔隙长度L、等效宽度W和形状因子Rs等定量表征孔隙几何形貌参数的变化规律。结果表明：孔隙长度L和等效宽度W分别在10～350μm和10～100μm范围内;随孔隙率的增加,L和W增大,且L比W增大的幅度大;孔隙率由0.03%增加到4.96%,圆形和椭圆形孔隙的比例减少,不规则形孔隙的比例增加。该研究结果为建立准确的孔隙率超声衰减法检测模型提供了重要的试验依据。     

《固结磨具纤维增强树脂切割砂轮》标准的探讨

本文回顾了纤维增强树脂切割砂轮标准演化的历史,介绍了JB/T 4175 - 2006《固结磨具纤维增强树脂切割砂轮》标准与JB/T 4175 - 1994《纤维增强树脂薄片砂轮》相比的主要变化,包括标准名称、适用范围、极限偏差、形位公差、单点侧向负荷试验方法、三点侧向负荷试验方法、侧向抗冲击负荷试验方法等;修订后的标准...     

Fatigue crack growth behavior and fiber orientation of glass fiber reinforced polycarbonate polymer composites

The use of polymer-based composites has become increasingly common in the aeronautical and automotive industries. In this study, the fiber orientation of polymer composites was observed using microtoming techniques and the fatigue behavior of these composites was experimentally studied under mechanical loading. This involved the mechanical properties for parent and weld parts of polycarbonate (PC) composites in a tensile test and SEM. It was found that the tensile and hardness properties depended on the fiber orientation in the parent and weld parts of PC composites. Fatigue crack growth behavior depending on the fiber orientation was different in the parent and weld parts, according to a low cyclic-loading test.     

Application and prospect of computer technology in welding materials field

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Resistance welding of carbon fibre reinforced polyetheretherketone composites using metal mesh and PEI film

Weldability of polyetheretherketone( PEEK) with polyetherimide( PEI) is tested. And carbon fiber reinforced PEEK laminates are resistance welded using stainless steel mesh heating element. The effects of the welding time and welding pressure on the lap shear strength of joints are investigated. Results show that PEEK can heal with PEI well in welding condition and the lap shear strength of PEEK/CF(carbon fibre) joint increases linearly with welding time, but reaches a maximum value when welding pressure ranging from 0.3 MPa to 0.5 MPa with constant welding time. The fracture characteristics of surface are analyzed by SEM techniques, and four types of fracture modes of lap shear joints are suggested.     

Study on the usability and robustness of polymer and wood materials for tooling in sheet metal forming

The traditional market of sheet metal parts is based in high production volumes normally greater than 10.000 parts by using high-speed presses and highly automated operations, being the tooling usually made from steel or cast iron, which ensures the needed robustness for such production volumes. Current trends in stamping industries can be characterized by the increasing demand for individualization of products which leads to a growing development towards an increasing number of product variants, lower production volumes and shorter innovation cycles. These trends have triggered research in the development of faster and cost-effective tool manufacturing techniques suitable for low production volumes, since high investments in steel tools can only be compensated by huge volume series of one and the same part during long life cycles. A promising approach for production of small series of complex sheet metal parts is the use of non-conventional tooling materials such as polymers, wood and low melting point metals. The usage of these alternative materials in tooling is still looked with some suspicion, due to the lack of know-how on its processing and also on its wear durability, influenced by the required product geometry, blank material and expected production volume.

In this paper a study on the use of non conventional materials for tooling, to be used for producing a complex sheet metal part, is performed. The evolution of tool wear, roughness and geometrical changes in punch and die radius were measured and its influence in the stamped part geometry evaluated, for an imposed production volume target of 500 parts. Also a comparative study of the tooling costs is presented in order to assess the aptitude and economical feasibility of the use of these tooling materials for low production series.     

时效处理对铝合金A6061与碳纤维增强热塑性复合材料激光连接接头的影响

采用激光直接连接技术对铝合金(A6061)与碳纤维增强热塑性复合材料(Carbon Fiber Reinf-orced Thermal Plastic,CFRTP)进行连接,以接头抗拉强度作为评价指标,确定连接参数的影响规律及最优连接工艺.采用时效处理的方法提高接头连接强度,研究时效处理参数对拉伸强度的影响,揭示最优工...     

Effects of precoating and calcination on microstructure of 3D silica fiber reinforced silicon nitride based composites

1 Introduction Continuous fiber reinforced ceramic matrix composites, such as C/SiC, C/Si-C-N, C/Si-O-C and SiC/SiC systems[1?5], have received considerable attention because of their excellent thermal stability, light mass and high toughness, etc. Among…