1、 The use of Nanocomposites in Automotive ApplicationsP151546_PT-172.indb 1 12/11/15 9:19 AMOther SAE books of interest:Design of Automotive Composites By Charles Lu and Srikanth Pilla(Product Code: PT-164)Biocomposites in Automotive Applications By Charles Lu and Srikanth Pilla(Product Code: PT-165)
2、CAE Design and Failure Analysis of Automotive Composites By Charles Lu and Srikanth Pilla(Product Code: PT-166)For more information or to order a book, contact: SAE INTERNATIONAL400 Commonwealth Drive Warrendale, PA 15096Phone: +1.877.606.7323 (U.S. and Canada only) or +1.724.776.4970 (outside U.S.
3、and Canada)Fax: +1.724.776.0790 Email: CustomerServicesae.org Website: books.sae.orgP151546_PT-172.indb 2 12/11/15 9:19 AMThe use of Nanocomposites in Automotive ApplicationsBy Charles Lu and Srikanth PillaWarrendale, Pennsylvania, USAP151546_PT-172.indb 3 12/11/15 9:19 AMCopyright 2016 SAE Internat
4、ional eISBN: 978-0-7680-8284-5Copyright 2016 SAE International. All rights reserved.No part of this publication may be reproduced, stored in a retrieval system, distributed, or transmitted, in any form or by any means without the prior written permission of SAE International. For permission and lice
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10、 9:19 AMvTable of Contents Introduction to Nanocomposites . 1Perspectives of nanocomposites in the automotive industry 7Nanomaterials A New Dimension in Automotive Engineering (2006-01-0105) .9Nanocomposites: Recent Development and Potential Automotive Applications (2008-01-1263) 17Nanotechnology Ap
11、plications in Future Automobiles (2010-01-1149) .27Nano-fiber reinforced composites . 39Polyamide 6 Reinforced With Carbon Nanotubes for Automotive Parts 41(2008-36-0132)Mechanical Properties of MWCNT/Elastomer Nanocomposites and the Cellulation Model (2009-01-0606) .47Development of a Transparent N
12、anocomposite for Automobile Polymer Glazing (2012-01-0749) .53Nano-platelet reinforced composites 59Twenty-Year Review of Polymer-Clay Nanocomposites at Toyota Central R thus, it has superior electrical conductivity. The CNT also has very high thermal conductivity: 3500 W/m/K, compared to 385 W/m/K
13、for copper 1-6. Due to the exceptional mechanical, thermal, and electrical properties, carbon nanotubes have long been considered as ideal reinforcement fillers to make strong, multifunctional composites. CNTs can be dispersed into polymer matrices through conventional molding processes to form fibe
14、r reinforced nanocomposites. A polystyrene nanocomposite with only 1% CNT is reported to have exhibited a 36-42% increase in elastic stiffness and 25% increase in tensile strength 1-7. The properties of PMMA (polymethyl methacrylate) nanocomposites with a 5% CNT content have shown increases in tensi
15、le strength and modulus by 90% and 150%, respectively 1-8. The integration of carbon nanotubes also has improved the fracture toughness of polymers. An epoxy based nanocomposite with 3% CNT fibers has shown a 62% increase in fracture toughness, and the same composite with only 0.5% CNT fibers has it
16、s fatigue life increased by almost 10 times 1-9. Further, due to the strong interfaces between CNT fibers and polymer matrices, the dynamic mechanical properties of the nanocomposites have been improved: with an addition of CNT of only 0.5-1%, the damping ratio of the epoxy based composites has been
17、 increased by 1400% 1-10. Although significant improvements exist, CNT nano-fiber composites have not exhibited the ideal properties as promised. This is due to the poor dispersions of the CNT fibers in polymer matrices. Because of the van der Waals interactions between individual nanotubes, the CNT
18、 fibers are often agglomerated. In addition, the long CNT fibers can become highly wavy (non-straight) during the molding processes and thus significantly lose their strength. Different techniques have been attempted in achieving consistent dispersion and alignment of the CNT fibers in polymer matri
19、ces. These include the in situ polymerization of nanocomposites, the use of polymers to coat nanotube surfaces, ultrasonic dispersion of carbon nanotubes in solution, the electrospinning technique, etc. The use of a high magnetic field to align the nanotubes has been attempted, and the resultant CNT
20、 nanocomposite has exhibited a much improved modulus and transition temperature 1-11. (2) Nano-Platelet Reinforced CompositesThe most commonly used nano-platelets are the layered silicates. Layered silicates are from the smectite family of clays, so the nano-platelets are also referred to as nano-cl
21、ays. The most widely used nano-clay employed in composites is the modified montmorillonite clay. Montmorillonite is a two-to-one layered smectite clay mineral with a platy structure. Each layer has two tetrahedral sheets containing an octahedral sheet between them. Individual platelet thicknesses ar
22、e just 1 nm, but the lateral dimensions are in the range of 100-1000 nm, resulting in unusually high aspect ratios. The specific surface area of the nano-clay filler is estimated to be approximately 700,000 m2/kg. Hundreds or thousands of these layers are stacked together with van der Waals forces t
23、o form clay particles 1-12.Nano-clay reinforced nanocomposites are of great interest in the industry because they show substantial enhancements of material properties. Two decades ago, Toyota introduced the first nano-clay polymer nanocomposites. With the incorporation of only 4.2% nano-clay platele
24、ts, a doubling of the tensile modulus and strength is achieved for nylon based nanocomposites, along with an 80oC increase in the heat distortion temperature 1-13. Subsequent studies have shown that nano-clay composites have exhibited many other advantages, including enhanced barrier characteristics
25、 1-13, 1-14, reduced gas permeability 1-15, increased modulus and strength 1-14, a high heat distortion temperature 1-16, and a decreased thermal expansion coefficient 1-17. Nano-clay composites are lightweight materials that rival metals in stiffness and strength, so they are expected to be widely
26、applicable to heat-resistant materials, film materials, and automobile lightweight plastic materials. The key to obtaining high-performance nano-clay composites is to have a fully exfoliated, homogeneous dispersion of the nano-clay platelets in polymer matrices. The silicate is naturally hydrophilic
27、, which makes it incompatible with a non-polar polymer matrix. The methods used to overcome this difficulty fall into two categories. The first one focuses on the modification of the layered silicates by using organo-intercalant to reduce the interaction between the clay platelets while simultaneous
28、ly making them more compatible with the polymer matrix. The second method concerns modification of the polyolefin matrix by incorporating a more hydrophilic coupling agent to make it more compatible with the clay 1-18.P151546_PT-172.indb 2 12/11/15 9:19 AM3(3) Nano-Particle Reinforced CompositesNano
29、-sized particles are defined as spherical particles with diameters that are 100 nm and less. Unlike nano-sized fibers and nano-sized platelets, nano-sized particles are available in a wide range of materials, including metal (Al, Fe, Au, Ag, etc.), metal oxide (ZnO, Al2O3, CaCO3, TiO2, etc.), non-me
30、tal oxide (SiO2), and others (SiC). Each type of nanoparticle has certain advantages and disadvantages. For example, Al nano-particles have very high conductivity, CaCO3 particles are known for relatively low cost, and SiC nano-particles possess great hardness and stiffness. The selection of nano-pa
31、rticles generally depends on the desired mechanical, thermal, and electrical properties of the nanocomposites. Nano-sized particle enhanced composites have shown significant improvement in mechanical, thermal, and electrical properties. For example, polyamide nanocomposites filled with 5% silica nan
32、o-particles have been shown to increase the tensile strength by 15%, strain-to-failure by 150%, Youngs modulus by 23%, and impact strength by 78% 1-19. Polyethylene nanocomposites with TiO2nano-particles have shown significant improvement in electrical properties. It is reported that the PVA nanocom
33、posite with 1% Ag nano-particles has its glass transition temperature increased by 20K and thermal stability improved by 40K 1-20. Nano-particles have been commonly used for preparing metal-based nanocomposites. SiC nano-particle reinforced Al composites have displayed notably high modulus and hardn
34、ess 1-21. Pb nano-particle reinforced Al composites have had greatly improved frictional features 1-22. The important issue in achieving high-quality nano-particle composites is to have a strong interaction between nano-sized particles and matrices. Preparation methods should facilitate a strong che
35、mical covalent or ioniccovalent bond between the organic and inorganic phases in the composites. Common methods for preparing polymer/inorganic particle nanocomposites include in situ polymerization, solution blending, melt compounding by twin-screw extrusion, and high shear mixing with three roll m
36、illing.Nanocomposites for Automotive Applications For the past decade or so, composites have been experiencing several transitions, one of them being the transition from micro-scale reinforcement fillers to nano-scale reinforcement fillers, which has resulted in a new type of composites: the nanocom
37、posite. This type of composites has tremendous advantages over conventional composites, and thus it is expected to have a profound effect on the automotive industry. This book presents the historical development and practical applications of nanocomposites in the automotive industry. The chapters co
38、nsist of technical papers selected from the automotive composites and other relevant sessions that the editors have organized for the SAE World Congress over the past decade. The book begins with a section on the perspectives of nanocomposites in the automotive industry. It consists of three excelle
39、nt review papers given by experts from the automotive industry and academia: Nanocomposites: Recent Development and Potential Automotive Applications by Wang and Xiao from University of New Brunswick, Nanomaterials A New Dimension in Automotive Engineering by Stauber and Cecco from BMW, and Nanotech
40、nology Applications in Future Automobiles by Wallner et al. from Delphi. Following the perspective are three sections on the three major nanocomposites (Figure 1.3): Nano-fiber reinforced composites Nano-platelet reinforced composites Nano-particle reinforced compositesThe section on nano-fiber rein
41、forced composites consists of three papers on the uses of carbon nanotube fibers and boehmite fibers in composites. The matrix materials used are polyamide thermoplastic, nitrite rubber, and polycarbonate glass. The section on nano-platelet reinforced composites consists of three papers on the uses
42、of nano-clays in composites, including an excellent review paper on the historical development of nano-clay polymer composites at Toyota R whereas nanodispersion hardened Cr-layers are already implemented on valves in diesel engines. In order to obtain scratch resistant polymeric surfaces, surface c
43、oatings with hard nanoparticles are used, for example as a coating on polycarbonate glazing or in paint with high scratch resistance. Though highly promising, there are still several problems to overcome with most developments of functional surfaces. High costs of production, stability, durability,
44、reliability and technological problems in production have to be considered in this context. While some ideas are ready for application in series production, others are still in the development stage or have to be seen as future visions. NANOPARTICLE REINFORCED MATERIALS Carbon black is well establis
45、hed as filler in tires. New developments of carbon black nanoparticles improve properties like rolling friction or the lifetime of a tire, while nanoscaled silica is integrated in the tread to improve wheel grip. Nanoparticle reinforced construction materials metals and polymers - show highly promis
46、ing potential, although most of the applications are still under development or in prototype stage. Marked improvements in mechanical strength and stiffness, as well as an improved heat resistance or less thermal elongation are benefits that can be obtained by nanoparticle reinforcement. In this con
47、text, high expectations focus on the potential of carbon nanotubes in composite materials, promising remarkable mechanical stiffness with low specific weight 14. P151546_PT-172.indb 12 12/11/15 9:19 AM13Metals containing nanoscale phases are produced by the segregation of nanophases during appropria
48、te thermal treatments. Steels of high strength and very good hot formability are already commercially available 15. Metal matrix composite (MMC) materials are reinforced by adding nanoparticles of a different material, especially ceramic nanoparticles. These materials show an increased fracture resi
49、stance and can undergo frequent changes in temperature without damage. As an example, the tensile strength of Aluminum that is reinforced with oxide nanoparticles can reach twice the value of a conventional AlMgSi-alloy 14. Nanocomposites Nanocomposites are prominent examples for reinforced polymers and have the potential to replace conventional plastics in areas such as interior applications, exterior body parts, polymeric glazing, the en
