复合材料定义ppt课件.ppt

《复合材料定义ppt课件.ppt》由会员分享，可在线阅读，更多相关《复合材料定义ppt课件.ppt（86页珍藏版）》请在三一办公上搜索。

1、2022/12/24,1,复合材料定义,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相固体材料。在复合材料中，通常有一相为连续相，称为基体；另一相为分散相，称为增强材料。两相之间存在着相界面。虽然复合材料的组分材料保持着其相对的独立性，但其性能却不是组分材料性能的简单相加，而是相互“取长补短”，有着协同作用，极大的弥补了单一材料的缺点。在一定程度上讲，它综合了各种材料如纤维，树脂，橡胶，金属，陶瓷等的优点。,Advantages of composite materials,材料性能指标的自由设计性材料与结构的一致性产品型体设计的自由性,2022/12/24,3,复合材料

2、的主要优点,比强度，比模量大（以碳纤维，硼纤维及有机纤维增强的聚合物基复合材料的比强度相当于钛合金的35倍，比模量相当于金属的4倍之多）耐疲劳性能好（聚合物基复合材料中纤维与基体的界面有能阻止材料受力所致的裂纹扩展的效果）减震性好（一是由于其具有高的自振频率，二是由于复合材料的界面具有吸振能力，使材料的震动阻尼很高）过载时安全性好（当过载时，一部分纤维断裂，载荷会迅速重新分配到未破坏的纤维上）有很好的加工工艺性（有多种加工工艺如手糊成型，模压成型，挤拉成型等）,复合材料的分类,按基体材料分主要有:聚合物基复合材料金属基复合材料无机非金属基复合材料（包括陶瓷基和水泥基,复合材料的分类,按增强纤维

3、种类分主要有玻璃纤维复合材料碳纤维复合材料有机纤维复合材料（包括芳香族聚酰胺纤维，芳香族聚酯纤维和高强度聚烯纤维等）金属纤维陶瓷纤维,2022/12/24,6,聚合物基体的作用,把增强纤维粘在一起分配增强纤维间的载荷保护增强纤维不受环境的影响,2022/12/24,7,聚合物基体,常用作基体的聚合物不饱和聚酯树脂，环氧树脂，酚醛树脂耐高温树脂热塑性聚合物辅助材料：固化剂，增韧剂，稀释剂，催化剂等,复合材料的界面,复合材料界面的重要性复合材料界面的理论复合材料界面的表征纤维表面处理,增强纤维表面改性,气相氧化法（Dry Gaseous Oxidation） 液相氧化法（Wet Chemical

4、Oxidation）化学偶联剂处理法（Chemical Coupling）聚合物涂层法（Polymer Coating）（涂覆）沉积法（Deposition） 电聚合与电沉积法 化学接枝聚合法（Chemical Grafting） 等离子体处理方法（Plasma）,Application of composites,See composite materials 1,复合材料成型,Hand lay-up moldingSpray-up moldingRTM(Resin transfer molding)RIM(Reaction injection molding)Resin infusionS

5、heet molding compoundBulk molding compoundFilament windingPultrusionLFRTP,Hand lay-up molding,Hand lay-up moulding may be used for the production of parts of any dimensions, for example, technical parts of a few tens of m area, as well as swimming pools of 150 m developed area.But, this method is ge

6、nerally limited to the manufacture of parts with relatively simple shapes, requiring only one face to have a smooth appearance (the other face being rough from the moulding operation).It is recommended for small and medium volumes, for which the investment in moulds and equipment should not be very

7、high.,Hand lay-up moulding,The contact moulding method consists of applying successively onto a mould surface :- a release agent- a gel coat- a layer of liquid thermosetting resin, of viscosity between 0.3 and 0.4 Pa.s, and of medium reactivity- a layer of reinforcement (glass, aramid, carbon etc.)

8、in the form of chopped strand mat or woven roving and to impregnate the reinforcement by hand with the aid of a roller or a brush.This operation is repeated as many times as there are layers of reinforcement, in order to obtain the desired thickness of the structure.,Spray-up moulding,Spray-up mould

9、ing is derived from hand lay-up moulding, and is particularly suited to parts of medium to large dimensions and simple shapes. Parts produced by spray-up are pleasure boat hulls, swimming pools, covers, end caps of large diameter tanks, reinforced acrylic bathtubs etc. Productivity is better compare

10、d to hand lay-up moulding.,Spray-up moulding,The process consists of simultaneously spraying onto the mould, chopped glass strands, normally of 30 mm length, and the resin necessary for their impregnation. After spraying onto the mould, rolling by hand is necessary to flatten or compact the glass-re

11、sin mixture well onto the mould surface and, as far as possible, eliminate air bubbles generated by the spraying system.The spray machine generally consists of - a glass chopper driven by compressed air,- a pneumatic pump for feeding resin to the spray gun,- A solvent delivery system for cleaning th

12、e gun.,RTM,RTM allows the moulding of components with complex shape and large surface area with a good surface finish on both sides. The process is suited for short and medium production runs and is employed for many different transport applications (truck cabs are an example).,RTM,This process cons

13、ists of filling a rigid and closed mould cavity by injecting a resin through one, or several, points, depending on the size of the component. The reinforcements are previously placed in the interior of the mould, before closing and locking it firmly.Usually, polyesters, epoxy, phenolic & acrylic res

14、ins are used, and they can be filled if needed. Different types of mould can be used, depending on the required production rate: Heat can be applied to the mould to shorten the cure-time, in which case steel moulds may be necessary. Low profile resins can be employed with heated moulds to improve th

15、e surface finish and appearance of the moulded part. Alternatively, low pressure RTM allows lower cost, composite tooling to be used with low tonnage presses.The reinforcements may be continuous filament mats, complexes or fabrics, but generally continuous filament mats are the most widely used. The

16、 use of preforms from continuous strand mats permits a considerable increase in production rate to be achieved.,Reaction Injection Molding,The RIM process is based on the injection of the two polyurethane components (a polyol and an isocyanate) inside a mould cavity. The automotive market offers the

17、 most important applications for this process, such as dashboards, interior panels and under body shields. Many truck components are also manufactured by RIM, such as bumper-beams, front-ends and grills.,RIM,The principle of RIM consists of injecting into a closed mould and under low pressure (0.5 M

18、Pa), two or more reactive components mixed within a nozzle, just prior to their injection into the mould.The reaction, in the case of a polyol and an isocyanate, leads to the formation of a polyurethane.The introduction of short strands, such as milled fibres, directly into one of the two reactive c

19、onstituents, leads to the injection of a pre-reinforced mixture. This is known as R-RIM Reinforced Reaction Injection Moulding. The introduction of long strand reinforcements - such as continuous filament mats, fabrics, complexes or chopped strand preforms - into the mould before the injection takes

20、 place, allows parts with higher mechanical performance to be obtained. In this case, the process is known as S-RIM (Structural Reaction Injection Moulding.,Resin infusion,Resin infusion offers an environmental friendly alternative to open moulding. Resin infusion is able to produce consistently hig

21、h quality parts, such as pleasure boats and windmill blades. The process allows thick structures measuring several metres and of complex shape, with the possibility of incorporating cores and inserts, to be moulded.,Resin infusion,The principle of the process is the impregnation of layers of dry rei

22、nforcement contained between a rigid, airtight, mould and a flexible sheet sealed to it around its perimeter. A partial vacuum is applied to the mould cavity before resin is allowed to infuse into the reinforcement under atmospheric pressure, impregnating both across and down through the reinforceme

23、nt layers. The upper sheet is removed once resin cure is complete, and the component may be removed.,Sheet Molding Compound,SMC is a combination of chopped glass strands and filled polyester resin, in the form of a sheet. Processing of SMC by compression or injection moulding enables the production

24、of bodywork or structural automotive components, and electrical or electronic machine housings in large industrial volumes. The process also penetrates sectors such as sanitary ware (baths) and urban furniture (stadium and cinema seating), etc.,Sheet Molding Compound,The prepreg contains all the com

25、ponents needed for moulding the final part (resin, reinforcement, filler, catalyst, low profile additives, etc.) in a malleable and non-tacky sheet. Its characteristics allow it to fill a mould under the conditions of moulding temperature and pressure employed.SMC prepreg is made from glass strands

26、chopped to lengths of 25 or 50mm, sandwiched between two layers of film, onto which the resin paste has already been applied. The prepreg passes through a compaction system that ensures complete strand impregnation before being wound into rolls. These are stored for a few days before moulding, to al

27、low the prepreg to thicken to a mouldable viscosity,Bulk Molding Compound,BMC is a combination of chopped glass strands with resin in the form of a bulk prepreg. BMC is suitable for either compression or injection moulding. Injection moulding of BMC is used to produce complex components such as elec

28、trical equipment, car components (headlamps are an important application for BMC), housings for electrical appliances and tools, in large industrial volumesMC is a combination of chopped glass strands with resin in the form of a bulk prepreg. BMC is suitable for either compression or injection mould

29、ing. Injection moulding of BMC is used to produce complex components such as electrical equipment, car components (headlamps are an important application for BMC), housings for electrical appliances and tools, in large industrial volumes,Bulk Molding Compound,Unlike SMC, it is not necessary to inclu

30、de a maturation stage, and consequently, BMC prepreg formulations contain higher filler contents.The reinforcements are essentially chopped glass strands of 6 or 12mm length, but sometimes 25mm for applications which demand a high mechanical performance. The reinforcement content is generally betwee

31、n 15 and 20%. It may be possible to reach 25% for the highest performance. BMC has a lower reinforcement content than SMC, which permits the introduction of higher filler loadings with a consequent economic benefit.,Continuous Sheet Production,Continuous moulding between layers of film is used for t

32、he continuous production of sheets, both coloured and translucent, in flat or profiled (such as corrugated) forms. The main applications are in building (cladding and roofing) and agriculture (greenhouses).5-15/min,Pultrusion,Pultrusion is a continuous process able to produce full or hollow, glass r

33、einforced, profiles of different shapes. Depending on the design and the shape, glass contents may range from 30 to 70 % by weight.Pultruded profiles are used in many applications in electrical, corrosion resistant, building and consumer goods areas0.5-2m/mi,Filament winding,Filament winding produce

34、s hollow items such as tubes, pipes, elbows, tanks and vessels with a typical 70 : 30 glass : resin weight ratio.,Glass Mat reinforced Thermoplastics,GMT is a thermoplastic prepreg, which offers better mechanical properties than injection moulded reinforced thermoplastics, thanks to the higher resid

35、ual length of the glass strands.GMT is widely used in automotive applications such as under body shields, seat structures, front-ends etc.,Glass Mat reinforced Thermoplastics,GMT is obtained by consolidating a glass strand mat with a sheet of polypropylene. The glass mat is obtained by chopping asse

36、mbled rovings, and then needling the strands together. The intermediate product is delivered in the form of rigid sheets, which are subsequently moulded by the end user.GMT is processed by heating the sheets to the matrix softening temperature, usually in an infrared oven, followed by compression mo

37、ulding in a mould maintained at a lower temperature. During moulding, GMT flows inside the mould cavity enabling complex features to be incorporated.GMT permits a high level of automation during blank cutting, pre-heating and placing into the mould.,LFT/extrusion-compression,1,LFT/extrusion-compress

38、ion,Extrusion / compression moulding uses an extruder to convert glass strands and PP pellets into a hot bulk moulding compound. The molten charge is quickly transferred to a press where it is moulded while still hot. The part is then removed after sufficient cooling. This process is generally refer

39、red to as Long Fibre Thermoplastic (LFT) processing. In direct LFT processing the glass strands are introduced into the extruder in the form of a roving or chopped strands. It is also possible to use pellets incorporating long strands in combination with PP pellets.,21世纪复合材料将是我国发展一个新的增长点,下世纪人类将面临很多问

40、题其中一个非常重要的问题是资源和能源枯竭的问题。煤200年，石油50年，天然气70年，资源也很缺乏，锡已用完总储量的20，而且都是无法回收的资源。,复合材料已在尖端领域中起了非常重要的作用；复合材料由于价格偏高和可靠性相对较差，阻碍了它的更大发展；下世纪人类面临的问题将给复合材料带来很大的机遇,复合材料的进一步发展有以下几个关键,降低成本，提高可靠性，开发新型复合材料，改善与环境的协调性,21世纪人类面临的问题及复合材料能起的作用问题能源和资源的枯竭环境污染信息技术发展的需要生活质量的提高作用新能源的开发，节能、储能材料；陆地、海洋和空间的开发；废弃物的利用，生物复合物；功能敏感材料；交通器材

41、和住房条件的改善例风力、潮汐发电，利用太阳能、地热能，海洋平台、飞船空间站，自感应自调节自修补人体、结构材料,复合材料在基础研究方面的新增长点：,各种新技术的发展，要求材料具有多种功能，而复合材料是最佳的优选对象如隐身蒙皮（台湾100亿）力学性能吸收电磁波吸收红外线摩擦器件力学性能摩擦系数调节磨耗小导热耐热器材力学性能导热热膨胀匹配耐腐蚀件力学性能耐介质腐蚀多功能建筑构件力学性能绝热隔音太阳能发电瓦片,复合材料在基础研究方面的新增长点：,复合材料的非线性复合效应和混杂效应的研究 复合材料的非线性复合效应和混杂效应包括乘积效应、系统效应、诱导效应和共振效应等，是开发新型功能复合材料的源泉。,复合

42、材料在基础研究方面的新增长点：,界面研究 用于结构的复合材料界面的力学行为研究很多，也已基本清楚。但多功能复合材料界面对功能的传递行为的研究尚属空白。,几种新型复合材料的研究,纳米、智能、仿生等新型复合材料在下世纪肯定会得到发展，但有很多基础问题需深入研究。纳米复合材料具有很多特异的性能，关键是如何均匀分布在介质中，而且在价格过程中不使纳米粒子或晶体团聚和长大。目前，用原位生成纳米相的方法是有效的，但需研究其过程和基制。,几种新型复合材料的研究,几种新型复合材料的研究,几种新型复合材料的研究,复合材料的虚拟与拟实设计的研究复合材料的主要特点是可设计性强，因此必然要研究用先进的计算机技术来优化。

43、光虚拟不行，要反过来拟实才行。,应用方面的问题：,复合材料用于基础设施如高速公路、桥梁大坝、海洋平台、港口机场、运动场馆等大型建筑，可使建筑行业设计、功能、成本、寿命和修复等产生革命化的变化研究开发水泥基复合材料，代钢筋，联接构件等。,有利于环境的复合材料相关研究；,复合材料的回收再生研究，包括分选技术和质量检测技术用废弃物组成性能较低但实用通用的材料(昆明回收中心将地膜和铁砂用双螺杆制窨井盖；将碎玻璃和废易拉罐盐熔制成矿井输送带轮，耐磨性非常好)自然降解的复合材料,连续纤维增强热塑性塑料,连续纤维增强热塑性塑料是聚合物基复合材料中新发展起来的一类重要品种。CFRTP较之已广泛应用的热固性复合

44、材料具有以下几方面突出优点:预浸料可长期保存具有优良的综合性能,特别是在高温、高湿度下仍能保持良好的力学性能成型方法多、生产效率高制品可重复加工、再生利用,因此，CFRTP自70年代初开发以来，越来越受到各国重视，研究应用十分活跃，在航天、航空、汽车、化工、电子/电器等领域均得到应用，发展速度很快。近10年来，每年以25%的速度增长，发展速度比热固性复合材料高数倍。,我国从80年代中后期也开展了CFRTP的研制工作，但是现在与发达国家相比，差距仍很大。然而，我国CFRTP的发展有着巨大的潜力，随着汽车、电子/电器工业的迅速发展，对CFRTP，特别是通用型CFRTP的需求会越来越大。因此在我国加

45、快CFRTP的研制和应用具有重要的现实意义。 大部分热塑性树脂都可作为CFRTP的基体，从通用树脂PP、PE、PVC到特种树脂PPS、PEEK等均可根据料的性能及成本加以选用。,纤维的种类及特点,纤维可以是各种纤维，如凯夫拉（Kevlar）纤维、碳纤维、玻璃纤维以及高强聚乙烯纤维、硼纤维、氧化铝纤维和碳化硅纤维。 增强纤维玻璃纤维、碳纤维和芳纶纤维是制造CFRTP的主要纤维品种。玻璃纤维由于其高强度、高模量，优良的耐热及低成本，用量最大。,用于CFRTP增强的玻璃纤维大多选用机械性能高、绝缘性能好的无碱玻璃纤维(E玻璃纤维)，并根据CFRTP制备方式的不同，纤维形态有：连续原丝针刺毡、单向随机

46、玻纤毡、连续玻纤织物和短切原等。其中针刺毡用于制作热塑性复合材料时，由于毡中的纤维呈三维分布有利于树脂的流动，并在冲压制品时易排气，减少了制品的缺陷，因而是目前制造通用CFRTP的最重要增强材料。,玻璃纤维毡增强热塑性复合材料(GMT)是目前国际上极为活跃的复合材料开发品种之一。这是一种以热塑性树脂为基体，以长玻璃纤维或连续玻璃纤维毡为增强材料的复合材料，一般制成片状以半成品供应。用不同类型的玻璃纤维毡和热塑性树脂基体，可以组成多种多样的GMT材料，热塑性树脂也可以根据用途进行选择，一般PP作为热塑性基体应用最为广泛，这是由于它具有良好的成本与性能之比；而GMT在再生利用方面取得的进展，在环保

47、要求越来越严的未来开发应用中更具竞争力。目前华东理工大学聚合物加工研究室已建成年产100150t的PP-GMT片材连续生产线，以替代进口材料。,碳纤维是制备高性能CFRTP的重要原料。碳纤维具有高比强、高模量、耐磨、导电、耐高温，长期受力不发生蠕变和疲劳等优点，用其增强的CFRTP主要用于航空、航天、医学、精密仪器及部分民用产品上。芳纶纤维也是以高强高模量的突出优点用于制造高性能热塑性复合材料，其拉伸模量远高于玻璃纤维且质轻，用芳纶纤维制造的CFRTP在很多领域得到应用，尤其是宇航工业。,CFRTP的制备技术,CFRTP是以热塑性树脂对连续纤维进行浸渍而制得。由于热塑性树脂的熔体粘度一般都超过

48、100NS/m2 ，很难使增强纤维获得良好浸渍。因此制备CFRTP的技术关键是如何解决热塑性树脂对连续增强纤维浸渍，对此，各国科学家进行了大量研究，主要开发了溶液浸渍、熔融浸渍、粉末浸渍、悬浮浸渍、混编浸渍、反应浸渍以及混纤法等多种制备技术。,1. 溶液浸渍制备技术,溶液浸渍技术是将树脂溶于合适的溶剂，使其粘度下降到一定水平，然后采用热固性树脂浸渍时所采取的工艺来浸润纤维，最后通过加热使溶剂除去。这种制备技术工艺简便，设备简单，但存在的问题是溶剂必须除去，因为极少的残余溶剂都有可能导致制品耐溶剂性的下降，此外在去除溶剂的过程中还存在物理分层、树脂纤维界面渗透以及溶剂可能聚集在纤维表面的小孔和空

49、隙内等，造成树脂与纤维界面不好。尽管如此，一些采用其它制备技术不易浸渍的高性能树脂基复合材料的制备大多仍采用这一浸渍技术 。,尽管如此，一些采用其它制备技术不易浸渍的高性能树脂基复合材料的制备大多仍采用这一浸渍技术 。一般的工艺流程如图。,2. 熔体浸渍制备技术,熔体浸渍是将热塑性树脂加热熔融后来浸渍纤维的一种制备技术。早在1972年，美国PPG公司就采用此技术生产连续玻璃纤维毡增强聚丙烯复合材料，采用的工艺是将两层玻纤原丝针刺毡夹在三层聚丙烯层之间，其中间层是挤出机挤出的熔融树脂，上下两层树脂即可用挤出机挤出，也可直接用树脂薄膜，然后将这种夹置于高于树脂基体熔化温度下进行热压，随后使之冷却成

50、型。,熔融浸渍工艺,首先将纤维材料预热，再与挤出机挤出的热塑性树脂模层合，经过双带压机热压浸渍后，固结、冷却、切割成一定尺寸的片材。在该工艺过程中，预热的增强材料分层与基础的聚合物接触，再在双带压机内固结。,目前这一技术已成功地用连续玻纤毡增强PBT、PET及PC等热塑性复合材料中，然而这种生产方法技术复杂、设备投资较大，一条年产万吨复合片材的生产线约需投资1千万美元以上。 熔体浸渍也可采用拉挤技术，即采用一种特殊结构的拉挤模头，使纤维束经过这一充满高压熔体的模头时，反复多次承受交替的变化，促使纤维和熔体强制性的浸渍，达到理想的浸渍效果，但这一方法只能用于生产长维增强粒料(长度一般切割成610