1、Overview of Composites,材料概論 An Introduction to Materials,7.1 An Overview of Composites 7.1.1 Introduction,It has been estimated that in 1979 the composite industry used a sufficient quantity of resins, reinforcing agents, and fillers to produce 8 billion pounds of composites.,fiberglass reinforcemen

2、t,asbestos 石棉r(nóng)einforcement,other reinforcements (cellulosic fiber, cotton, polyamide (nylon), and sisal),The history of composite,since the early 1940s, at which time the high-structural-strength RP were developed. (World War ),1941,1942,combed and carded cotton fibers impregnated with phenolic resi

3、n cured at 2000 pounds per square inch (psi),low-pressure-curing polyester-resin systems were developed,fiberglass-reinforced plastics (FRP) had been used successfully in structural applications.,1945,The application of composite,Following demobilization, RP based on a variety of reinforcing agents

4、and resins gradually entered civilian life as a material used in the manufacture of boats, cars, appliance housings, trays, storage containers ,and other items.,boats,cars,The application of composite,Spacecraft and areocraft,The application of composite,The application of composite,roof,profile,toi

5、let,appliance housings,The application of composite,storage containers and pipes,The application of composite,The application of composite,The growth of composite,Average consumption of composite per person (kg),The Definition of composite,1. It is manufactured.(人造) A composite is a combined materia

6、l created by the synthetic assembly of two or more components a selected filler or reinforcing agent and a compatible matrix binder (i.e., a resin) in order to obtain specific characteristics and properties.,2. It consists of two or more physically and/or chemically distinct, suitably arranged or di

7、stributed phases with an interface separating them.(兩種或兩種以上的物理、化學(xué)性質(zhì)不同的物質(zhì)組成) The components of a composite do not dissolve or otherwise merge completely into each other, but nevertheless do act in concert. 3. It has characteristics that are not depicted by any of the components in isolation.(單一材料不具備的

8、功能),composite(復(fù)合材料)=reinforcement(增強(qiáng)材料)+matrix(基體) example 骨頭bone collagen膠原質(zhì) apatite磷灰石 玻璃鋼FRP fiberglass玻璃 resin樹(shù)脂 混凝土concrete sand沙 cement水泥,The Classification of composite,on the basis of the form of their structural components (the reinforcing agent ),flake,skeletal,PMC,polymer matrix composite

9、 Matrix : polymer Reinforcement: glass, carbon,MMC,metal matrix composite Matrix : metal (aluminum) Reinforcement: SiC,ceramic matrix composite Matrix : ceramic Reinforcement: SiC, Boron(硼)in short fiber or whisker style,CMC,The Classification of composite,on the basis of the Matrix,The Materials of

10、 Matrix (PMC),The Materials of Construction,fiberglass,carbon,boron,glass, paper (cellulosic fiber), cotton, polyamide(聚酰胺)and other natural fibers, asbestos(石棉), sisal (劍麻), and jute(黃麻). Specialty agents include carbon, graphite, boron, steel, and whiskers,The Materials of Construction,Steel fiber

11、,whisker,kevlar fiber,The Materials of Construction,The Materials of Fillers,Reinforcing fillers used in large quantities include alumina powder (aluminum oxide), asbestos, calcium carbonate, calcium silicate, cellulose flock, cotton (different forms), fiberglass, glass beads and spheres, granite, i

12、ron oxide powder, mica云母, quartz石英, sisal劍麻, silicon carbide, titanium oxide, and tungsten鎢carbide.,The Advantage and disadvantages of Fillers,Advantage: increased strength and stiffness, heat resistance, heat conductivity, stability, wet strength, fabrication mobility, viscosity, abrasion resistanc

13、e, and impact strength; reduced cost, shrinkage, exothermic heat, thermal-expansion, coefficient, porosity, and crazing; and improved surface appearance.,Disadvantage: They may limit the method of fabrication, inhibit curing of certain resins, and shorten the pot life of the resin.,7.2. Surface Trea

14、tment of Reinforcing Materials,Purpose: Surface treatment is done to improve the adhesion of fillers and fibers to matrix resin by modifying the surface of the solid.改善增強(qiáng)材料的表面，增加與基體的結(jié)合 Methods: chemical, plasma, corona discharge and flame treatments 化學(xué)、等離子、電暈放電、火焰等,A. Glass Fibers 為可進(jìn)行水解反應(yīng)并生成的基團(tuán), 能夠

15、與無(wú)機(jī)材料發(fā)生化學(xué)反應(yīng),或吸附在材料表面,從而提高與無(wú)機(jī)材料的親和性。 、為兩類反應(yīng)特性不同的活性基團(tuán),其中易與無(wú)機(jī)物或礦物質(zhì)如玻璃、硅石、陶土、粘土、滑石、二氧化鈦和一些金屬如鋁、鈦、硅、鐵、銅、鋅等的鍵合能力。而則易與有機(jī)物中的樹(shù)脂、橡膠等產(chǎn)物有良好的結(jié)合。正是由于硅烷偶聯(lián)劑分子中間進(jìn)存在親有機(jī)和親無(wú)機(jī)的兩種功能團(tuán),可以把兩種不同化學(xué)結(jié)構(gòu)類型和親和力相差很大的材料在界面連接起來(lái),增加涂料和無(wú)機(jī)底層及顏料,填料與樹(shù)脂基料間的結(jié)合。,硅烷偶聯(lián)劑的作用過(guò)程提出了四步反應(yīng)模型,即(1)與硅相連的3個(gè)-基水解成;(2)之間脫水縮合成含的低聚硅氧烷;(3)低聚物中的與基材表面上的形成氫鍵;(4)加熱固

16、化過(guò)程中伴隨脫水反應(yīng)而與基材形成共價(jià)鍵連接。一般認(rèn)為,在界面上硅烷偶聯(lián)劑的硅與基材表面只有一個(gè)鍵合,剩下兩個(gè),或者與其他硅烷中的縮合,或者介質(zhì)游離狀態(tài)。,a small amount of a concentrated silane/organic solvent solution which is sprayed onto the fillers,a large amount of a dilute silane solution, typically of an aqueous solution(水溶液）, and the filler is suspended in a slurry f

17、orm.,dry blending method,slurry method,i. Dry Blending,Chemical reactions possible on a dry filler surface,The unreacted alkoxy（烷氧基的）groups will further react with the surface silanols（硅烷醇）or water on the filler surface. When the alkoxy groups are hydrolyzed（水解）, siloxane bonds between the silane mo

18、lecules can be formed.,Advantage: ease of drying Disadvantage: the alkoxy group of the coupling agent may not be completely hydrolyzed This results in small silane oligomers（低聚物）which are not chemically bound to the surface. This portion of the coupling agent, physisorbed silanes, migrates into the

19、matrix resin during processing and modifies the structure of the matrix near the filler surface creating a region termed matrix interphase whose properties differ from the matrix bulk.,Chemical processes during surface treatment of silaceous materials by a silane coupling agent.,ii. Prehydrolysis; S

20、lurry Treatment,Advantage: the slurry treatment avoided “cakes” more uniform surface treatment is achieved Disadvantage: need to be dried Dry method: After the surface treatment, the reinforcements are usually dried at room temperature overnight followed by a heat treatment at an elevated temperatur

21、e. A heat treatment at 110 for 5 to 30 min is typical. the drying may be done immediately after the surface treatment by passing through an oven.,B. Carbon fiber 碳維生產(chǎn)：PAN(聚丙烯腈)氧化碳化石墨化 碳維的表面構(gòu)造： 石墨基面(原子密排面) 晶緣(存在非六元環(huán)結(jié)構(gòu)hydroxyl、carbonyl、carboxylic acid groups) 未石墨化的碳,表面處理方法：氧化法修飾法(涂覆法) 氧化法increases the

22、 surface polarity and improves the adhesion with polymeric matrices. But the hydrothermal stability compromised. 增加表面極性和改善與基體結(jié)合 如oxidation in a concentrated nitric acid, electrochemical treatment, plasma treatment(等離子體處理) 修飾法用聚合物或低聚物填補(bǔ)或修飾表面(常用epoxies and polyimides)。 薄的修飾稱為finish，厚的稱為prim。,C. High M

23、odulus Organic Fibers,poly(para terephthal鄰苯二亞甲基amide) (PPT) : 1) plasma treatment: treating the PPT fibers in ammonium plasma at 50 W for 60 sec. Lead to Surface amination 2) Hydrolysis水解of the PPT surface: introduce the functional group for epoxidation環(huán)氧化作用but hydrolysis strongly influence the mec

24、hanical strength of the fibers,ultra-high modulus polyethylene（聚乙烯） Chemical treatment by chromic acid or fuming nitric acid, corona discharge（電暈放電）and plasma treatment are some of the techniques used.,7.3 Mechanical property of polymeric composite,Illustrating the combined effect on Modulus of the

25、addition of fibres to a resin matrix.,影響因素：纖維性質(zhì)樹(shù)脂性質(zhì)纖維體積百分比FVF纖維幾何分布,The trait of FRP composites,A composite material is formed at the same time, as the structure is itself being fabricated. This means that the person who is making the structure is creating the properties of the resultant composite m

26、aterial, and so the manufacturing processes they use have an unusually critical part to play in determining the performance of the resultant structure.,The response of a composite to tensile loads is very dependent on the tensile stiffness and strength properties of the reinforcement fibres, since these are far higher than the resin system on its own.,Tension,the adhesive and stiffness properties of the resin system are crucial, as it is the role of the resin to maintain the fibres as straight columns and to prevent them fr