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1、Material Science and TechnologyWang FangAn yang Institute of TechnologyChapter 7. Composites复合材料Classification of Materials 材料材料 实例实例 优点优点 缺点缺点金属材料金属材料钢铁钢铁无机非金无机非金属材料属材料普通玻璃普通玻璃聚合物材聚合物材料料塑料塑料硬度大硬度大易加工易加工易被腐蚀易被腐蚀抗腐蚀抗腐蚀耐高温耐高温易破碎易破碎耐腐蚀耐腐蚀易老化易老化不耐高温不耐高温MotivationslIt has always been the hope to produce
2、structural materials possessing both great ductility and extreme strength.lStrength provides load carrying capability while ductility prevents sudden failure.lStrength and ductility tend to be incompatible properties of simple, homogeneous materials.lThe idea of combining different materials seems t
3、o be a effective way.MechanismlMan-made composites are advantageous mechanically in that they typically combine the ductility and toughness of some matrix material with the load carrying ability of some introduced strong fibers or particles.lUnlike metal alloys, the matrix and reinforcement do not i
4、nteract chemically.lStructural composites often have superior strength-to-weight and/or stiffness-to-weight ratios compared with homogenous materials.Definition of compositelA composite is a combined material created by the synthetic assembly of two or more components a selected filler or reinforcin
5、g agent and a compatible matrix (基体) binder (e.g. a resin) in order to obtain specific characteristics and properties.Requirements for composites:ltwo or more chemically distinct constituentsldistinct interface separating constituents (different phases)lsignificant property difference among constitu
6、entslsignificant volume fractionl 复合材料在材料科学中是一门新兴学科，复合材料在材料科学中是一门新兴学科，理论尚不成熟，还没有形成统一的、普遍理论尚不成熟，还没有形成统一的、普遍接受的定义。国际化组织为复合材料下的接受的定义。国际化组织为复合材料下的定义：复合材料是由两种或两种以上物理定义：复合材料是由两种或两种以上物理和化学性质不同的物质组合而成的一种多和化学性质不同的物质组合而成的一种多相固体材料。相固体材料。l改进的定义：复合材料是由两种或两种以改进的定义：复合材料是由两种或两种以上物理和化学性质不同的物质采用适当的上物理和化学性质不同的物质采用适当的工
7、艺组合而成的一种多相固体材料，而且工艺组合而成的一种多相固体材料，而且这种多相固体材料的性能比单一材料的性这种多相固体材料的性能比单一材料的性能优越。能优越。复合材料定义要点l复合材料包含两种或两种以上物理上不同并可能用机械方法分离的材料。一般其中一种为连续相，另一种为功能增强相。l几种材料通过某种方法混合在一起获得复合性能。l复合材料的总体性能优于各单独组分材料，并在某些方面可能具有独特性能。Common examples of composite materialsCommon examples of composite materialsl木质素、纤维素Common examples o
8、f composite materialsl泥土-草复合材料A brief historyl3000 B.C.fiber (straw) reinforced mud bricks for huts and laminated woodl1940glass-polyester radomes (树脂穹顶)l1942molded fiber-glass boatsl1946U.S. government patented first filament-winding processl1960Boeing 727 employed reinforced plastic componentsl195
9、2single crystal whiskers (单晶须)lSincetennis rackets, large-diameter thin-walled pipes, golf clubs, automobile and truck components, skis, space vehicles, airplanes, etc.Composition of CompositeslComposite material system continuous phase (matrix) discontinuous phases (reinforcements)Functions of matr
10、ixlTo bind the reinforcementslTo transfer loadlTo protect reinforcements from environmental attacklTo protect reinforcements from damage due to handlingFunction of Reinforcementl限制微裂纹延伸l提高材料强度与刚性l改善材料抗疲劳、抗蠕变特性l提高材料使用寿命及可靠性复合材料的分类复合材料的分类（按照基体材料分类）lPolymer Matrix Composites (PMCs) Also known as FRP Fi
11、ber Reinforced Polymers (or Plastics) lMetal Matrix Composites (MMCs) Uses a metal such as aluminium as the matrix, and reinforce it with fibers such as silicon carbide.lCeramic Matrix Composites (CMCs) Uses a ceramics as the matrix and reinforce it with short fibers or whiskers made from silicon ca
12、rbide and boron.The Materials of ConstructionlThe primary reinforcing agents used in the production of composite at the present time are glass, paper (cellulosic fiber 纤维素纤维), cotton, polyamide (聚酰胺) and other natural fibers, asbestos (石棉), sisal (剑麻), and jute (黄麻). Specially agents include carbon
13、(碳纤维), graphite (石墨纤维), boron (硼砂), steel (钢纤维) and whiskers (晶须)fiberglasscarbonKevlar fiber凯夫拉纤维（芳纶纤维）The Materials of ConstructionSteel fiberwhiskerKevlar fiberBoron(硼砂)Primary Reinforcing AgentslCommon glass, paper, cotton, polyamide, other natural fibers, asbestos, sisal, jute.lSpecial carbon,
14、graphite, boron, steel, whiskers.Tensile strength of common materials for fibersTypical reinforcing agent Fiber GlasslKnown as fiberglass and glass fiberlMaterial made form extremely fine fibers of glass.lIt is used as a reinforcing agent for many polymer products.lThe resulting composite materials,
15、 properly known as fiber-reinforced polymer (FRP) or glass-reinforced plastic (GRP).Typical form of carbon fiberTypical reinforcing agent carbon fiberl碳纤维可以根据来源不同分为人造丝、石油（或煤的蒸馏残渣）以及PAN（聚丙烯腈）系碳纤维等。其特征也因原材料而有所差别。l碳纤维最突出的优点是： 强度高、模量高、密度小； 耐高温，可在2000使用，3000非氧化气氛中不熔不软； 耐酸，能耐浓盐酸、硫酸、磷酸、笨、丙酮等介质侵蚀； 热膨胀系数小，约等
16、于零； 热导率高；导电性好；摩擦系数小并具润滑性。Advantage of using reinforcing fillerlIncreased strength, increased stiffness, heat resistance, heat conductivity, increased impact strength, reduced cost, stability, wet strength, fabrication mobility, viscosity, abrasion resistance, shrinkage, exothermic heat, thermal-expa
17、nsion coefficient, porosity, crazing, surface appearancedisadvantageslThey may limit the method of fabrication, inhibit curing of certain resins, and shorten the pot life (存储期) of the resin.Application of compositeslApplication of MMClApplication of CMClApplication of PMCApplication of MMClThe most
18、obvious advantage of MMC to metal? StiffnessWhat protect against such a crash?l有人形容美国的校车是客车的设施、卡车的骨架，安全性是普通车辆的40倍。油箱四周有保护钢板，非常厚，将近4厘米，如果被撞倒，油箱不会漏油，不会着火或爆炸。 美国校车车声也极度坚固，内部都是特殊加固的 前后左右全部加装防撞钢梁，特殊加厚钢板，窗户上全部装的防弹玻璃，美国一辆校车价格都在几十万美金！ 而要知道美国丰田凯美瑞轿车等中档轿车在美国的售价只要2.2万美元， 而一辆Lexus豪华SUV也只要5万美元。“神舟”六号载人飞船“防护颈托”l航
19、天员在着陆冲击过程中最容易受损伤的部位是颈椎，防护颈托就是为保护航天员颈椎安全而设计的特殊吸能装置。看起来不大的防护颈托，却是一个技术难度很大的项目。它要求材料性能既要有高刚度，同时要具备低强度、高延伸率特性，但至今也没有一种材料能同时满足以上两个要求。Other advantageslHigher strengthlLess creeplEnhanced abrasion resistancelReduced densitylThermo propertiesApplication of CMCl与钛和不锈钢等金属材料相比： 质量轻、耐腐蚀、热稳定性好、线膨胀系数小。l应用： 汽车发动机、战车发动机、屏蔽材料、热交换器。Si3N4基复合材料l特点：具有优异的耐热性、耐热冲击性、热性和耐磨性；l应用：作为耐磨材料可以减轻磨损，在汽车中得到了良好的应用效果；在重油、原油火力发电机的火焰喷嘴中得到了应用。可望在宇宙、航空领域得到应用。Application of PMCl强度高、质量轻、使用方便、防腐、耐水、使用寿命长、综合性能高、节省能源、成本低、成型性能好。
