aluminium based composite materials applied to automotive industry

ALUMINIUM BASED COMPOSITE MATERIALS APPLIED TO AUTOMOTIVE INDUSTRY

MADE BY :

MOHD NASEEM AHMAD(2K13/ME/101)

MAYANK(2K13/ME/92)

RAHUL NEGI(2K13/ME/125)

HARBAN SINGH MEENA(2K13/ME/74)

ACKNOWLEDGEMENT

We would like to place on record my deep sense of gratitude to Prof. MR. R.S WALIA HOD-Training and Placement Department, D.T.U,Delhi and MR. RAVI BUTOLA, India for their generous guidance, help and useful suggestions.

SIGNATURE

MR. R.S WALIA

MR. RAVI BUTOLA

CERTIFICATE

We hereby certify that the work which is being presented in the B.Tech. Minor Project Report entitled “ALUMINIUM BASED COMPOSITE MATERIAL APPLIED TO AUTOMOTIVE INDUSRTY”, in partial fulfillment of the requirements for the award of the Bachelor of Technology in Mechanical Engineering and submitted to the Department of Mechanical Engineering of Delhi Technological University is an authentic record of my own work carried out during a period from August 2015 to November 2015( 5th semester) under the supervision of Mr. R.S Walia and M.r Ravi Butola, Mechanical Department.

Introduction

A Composite material is a material system composed of two or more macro constituents that differ in shape and chemical composition and which are insoluble in each other. The history of composite materials dates back to early 20th century. In 1940, fiber glass was first used to reinforce epoxy.

-Applications:

Aerospace industry

Sporting Goods Industry

Automotive Industry

Home Appliance Industry

Composite Survey

L arg e-p artic le

D isp ers ion -s tren g th en ed

P artic le -re in forced

C on tin u ou s(a lig n ed )

A lig n ed R an d om lyorien ted

D is con tin u ou s(s h ort)

F ib er-re in forced

L am in ates S an d w ichp an els

S tru c tu ra l

C om p os ites

Composite Survey: Particle-I

StructuralFiber-reinforcedParticle-reinforced

60

m

(brittle)

)

C3Fe

( cementi

te

particles:

(ductile)

ferrite ()

matrix:

steel

- Adapted from Fig. 10.19, Callister 7e. (Fig. 10.19 is copyright United States Steel Corporation, 1971.)

• Examples:

600

m5-12 vol

:mV hard(brittlWparticle

(ductilcobalmatri

carbide

cemented

- Adapted from Fig. 16.4, Callister 7e. (Fig. 16.4 is courtesy Carboloy Systems, Department, General Electric Company.)

0.75

m

(stiffer)

C

particles:

(compliant)

rubber

matrix:

tires

- Adapted from Fig. 16.5, Callister 7e. (Fig. 16.5 is courtesy Goodyear Tire and Rubber Company.)

Composite Survey: Particle-II

Composite Survey: Fiber

• Fibers themselves are very strong

– Provide significant strength improvement to material

– Ex: fiber-glass

• Continuous glass filaments in a polymer matrix

• Strength due to fibers

• Polymer simply holds them in place and environmentally protects them

Structuralaaaal

Fiber-reinforcedParticle-reinforcedConcrete – gravel + sand + cement

- Why sand and gravel? Sand packs into gravel voids Reinforced concrete - Reinforce with steel rebar or remesh

- increases strength - even if cement matrix is crackedPrestressed concrete - remesh under tension during setting of concrete. Tension release puts concrete under compressive force

- Concrete much stronger under compression. - Applied tension must exceed compressive force

Post tensioning – tighten nuts to put under rod under tension but concrete under compression

nutthreadedrod


Composite Survey: Fiber

• Fiber Materials

– Whiskers - Thin single crystals - large length to diameter ratio

• graphite, SiN, SiC

• high crystal perfection – extremely strong, strongest known

• very expensive

– Fibers

• polycrystalline or amorphous

generally polymers or ceramics

– Wires

• Metal – steel, Mo, W


Nanocomposites Composite material is a mixture of two or more materials or insoluble in one another, possessing properties which are superior to any of the component materials. Pedro et al. (2009); Seal et. al. (2004); Vencl, Rac and Bobic (2004) defined nanocomposites as a class of materials that contain at least one phase with constituents in the nanometre size range (1 nm = 10–9 m). Nanocomposite is a multi-phase material which has nano particles in its composition within its structure, the size will be less than 100 nm. The properties including mechanical, electrical and thermal may differ depending upon the composition of the materials used for the synthesis of the composites. Ozdemir et al. (2008) and Veeresh, Rao and Selvaraj (2011) shown that the structure and the properties of nanocomposites are controlled by the type and size of the reinforcement, nature of bonding and processing technique The amount, size and distribution of reinforcing particles in the metal matrix play an important and critical role in enhancing or limiting the overall properties of the composite material. Reinforcing aluminium matrix with much smaller particles, submicron or nano-sized range, is one of the key factor in producing high-performance composites, which yields improved mechanical properties A simple example of a normal composite is the concrete in our houses. It is a composite of cement, sand, and metal rod. These composition changes the overall property of the material used. It becomes so hard that it can withstand tonnes of load equally

a) CERAMIC MATRIX NANOCOMPOSITES (CMNC):- In this group of composites the main part of the volume is occupied by a ceramic, i.e. a chemical compound from the group of oxides, nitrides, borides, silicides etc. In most cases, ceramic-matrix nanocomposites encompass a metal as the second component. Ideally both components, the metallic one and the ceramic one, are finely dispersed in each other in order to elicit the particular nanoscopic properties. Nanocomposites improve their optical, electrical and magnetic properties as well as tribological, corrosion-resistance and other protective properties. Ceramic Matrix Nanocomposites include Al2O3/SiO2, SiO2/Ni, Al2O3/TiO2, Al2O3/SiC, Al2O3/CNT etc.

b) METAL MATRIX NANOCOMPOSITES (MMNC):- Metal matrix nanocomposites (MMNC) refer to materials consisting of a ductile metal or alloy matrix in which some nanosized reinforcement material is implanted. These materials combine metal and ceramic features, i.e., ductility and toughness with high strength and modulus. Thus, metal matrix nanocomposites are suitable for production of materials with high strength in shear/compression processes and high service temperature capabilities. They show an extraordinary potential for application in many areas, such as aerospace, automotive industries and other Metal Matrix Nanocomposites include Al/Al2O3, Al/SiC, Fe-Cr/ Al2O3, Ni/ Al2O3, Co/Cr, Fe/MgO, Al/CNT, Mg/CNT etc.

c) POLYMER MATRIX NANOCOMPOSITES (PMNC):- Adding nano particles to a polymer matrix can enhance its performance, often in very dramatic degree, by simply capitalizing on the nature and properties of the nanoscale filler. This strategy is particularly effective in yielding high performance composites, when good dispersion of the filler is achieved and the properties of the nanoscale filler are substantially different or better than those of the matrix, e.g. reinforcing a polymer matrix by much stiffer nanoparticles of ceramics, clays, or carbon nanotubes. Polymer Matrix Nanocomposites include thermoplastic/thermoset polymer/layered silicates, polyester/TiO2, polymer/CNT, polymer/layered double hydroxides.

Types of Nanocomposites a) Ceramic Matrix Nanocomposites (CMNC) b) Metal Matrix Nanocomposites (MMNC) c) Polymer Matrix Nanocomposites (PMNC)

Aluminium matrix compositesAluminiummatrixcomposites(AMCs)refertotheclassoflightweight highperformancealuminiumcentricmaterialsystems.ThereinforcementinAMCs could be in the form of continuous/discontinuous fibres, whisker or particulates, in volume fractions ranging from a few percent to 70%. Properties of AMCs can be tailoredtothedemandsofdifferentindustrialapplicationsbysuitablecombinations of matrix, reinforcement and processing route. Presently several grades of AMCs are manufactured by different routes. Three decades of intensive research have provided a wealth of new scientific knowledge on the intrinsic and extrinsic effects of ceramic reinforcement vis-a-vis physical, mechanical, thermo-mechanical and tribological properties of AMCs. In the last few years, AMCs have been utilised in high-tech structural and functional applications including aerospace, defence, automotive, and thermal management areas, as well as in sports and recreation. It is interesting to note that research on particle-reinforced cast AMCs took root in India during the 70’s, attained industrial maturity in the developed world and is currently in the process of joining the mainstream of materials. This paper presents an overview of AMC material systems on aspects relating to processing, microstructure, properties and applications.

Types of AMCsAMCs can be classified into four types depending on the type of reinforcement.

Particle reinforced aluminium matrix composites (PAMCs)

These composites generally contain equiaxed ceramic reinforcements with an aspect ratio less than about 5. Ceramic reinforcements are generally oxides or carbides or borides (Al2O3 or SiC or TiB2) and present in volume fraction less than 30% when used for structural and wear resistance applications. However, in electronic packaging applications reinforcement volume fraction could be as high as 70%. In general, PAMCs are manufactured either by solid state (PM processing) or liquid state (stir casting, infiltration and in-situ) processes. PAMCs are less expensive compared to CFAMCs. Mechanical properties of PAMCs are inferior compared to whisker/short fibre/continuous fibre reinforced AMCs but far superior compared to unreinforced aluminium alloys. These composites are isotropic in nature and can be subjected to a variety of secondary forming operations including extrusion, rolling and forging. Figure 1a shows the microstructure of cast aluminium matrix composite having high volume fraction (40 vol%) SiC particle reinforcements

Short fibre- and whisker-reinforced aluminium matrix composites (SFAMCs)

These contain reinforcements with an aspect ratio of greater than 5, but are not continuous. Short alumina fibre reinforced aluminium matrix composites is one of the first and most pop- ular AMCs to be developed and used in pistons. These were produced by squeeze infiltration process. Figure 1b shows the microstructure of short fibre reinforced AMCs. Whisker reinforced composites are produced by either by PM processing or by infiltration route. Mechan- ical properties of whisker reinforced composites are superior compared to particle or short fibre reinforced composites. However, in the recent years usage of whiskers as reinforcements in AMCs is fading due to perceived health hazards and, hence of late commercial exploitation of whisker reinforced composites has been very limited. Short fibre reinforced AMCs display characteristics in between that of continuous fibre and particle reinforced AMCs

Continuous fibre-reinforced aluminium matrix composites (CFAMCs)

Here, the reinforcements are in the form of continuous fibres (of alumina, SiC or carbon) with a diameter less than 20µm. The fibres can either be parallel or pre woven, braided prior to the production of the composite. AMCs having fibre volume fraction upto 40% are produced by squeeze infiltration technique. More recently 3MTm corporation has developed 60 vol%alumina fibre (continuous fibre) reinforced composite having a tensile strength and elastic stiffness of 1500 MPa and 240 GPa respectively. These composites are produced by pressure infiltration route. Figure 1c shows the microstructure of continuous fibre (alumina) reinforced AMCs.

Mono filament reinforced aluminium matrix composites (MFAMCs)

Monofilaments are large diameter (100 to 150µm) fibres, usually produced by chemical vapour deposition (CVD) of either SiC or B into a core of carbon fibre or W wire. Bending flexibility of monofilaments is low compared to multifilaments. Monofilament reinforced aluminium matrix composites are produced by diffusion bonding techniques, and is limited to super plastic forming aluminium alloy matrices.

In CFAMCs and MFAMCs, the reinforcement is the principal load-bearing constituent, and role of the aluminium matrix is to bond the reinforcement and transfer and distribute load. These composites exhibit directionality. Low strength in the direction perpendicular to the fibre orientation is characteristic of CFAMCs and MFAMCs. In particle and whisker reinforced AMCs, the matrix is the major load-bearing constituent. The role of the reinforcement is to strengthen and stiffen the composite by preventing matrix deformation by mechanical restraint.

In addition to four types of AMCs described above, another variant of AMCs known as hybrid AMCs have been developed and are in use to some extent. Hybrid AMCs essentially contain more than one type of reinforcement. For example, mixture of particle and whisker, or mixture of fibre and particle or mixture of hard and soft reinforcements. Aluminium matrix composite containing mixture of carbon fibre and alumina particles used in cylindrical liner applications is an example of hybrid composite

Primary processing of AMCsSolid state processing

Powder blending and consolidation (PM processing): Blending of aluminium alloy powder with ceramic short fibre/whisker particle is versatile technique for the production of AMCs. Blending can be carried out dry or in liquid suspension. Blending is usually followed by cold compaction, canning, degassing and high temperature consolidation stage such as hot isostatic pressing (HIP) or extrusion. PM processed AMCs, contain oxide particles in the form of plate-like particles of few tens of nm thick and in volume fractions ranging from 0·05 to 0·5 depending on powder history and processing conditions. These fine oxide particles tends to act as a dispersion-strengthening agent and often has strong influence on the matrix properties particularly during heat treatment.

Diffusion bonding: Mono filament-reinforced AMCs are mainly produced by the diffusion bonding (foil-fibre-foil) route or by the evaporation of relatively thick layers of aluminium on the surface of the fibre. 6061 Al-boron fibre composites have been produced by diffusionbondingviathefoil-fibre-foilprocess.However,theprocessismorecommonlyused to produce Ti based fibre reinforced composites. The process is cumbersome and obtaining high fibre volume fraction and homogeneous fibre distribution is difficult. The process is not suitable to produce complex shapes and components

Physical vapour deposition: The process involves continuous passage of fibre through a region of high partial pressure of the metal to be deposited, where condensation takes place so as to produce a relatively thick coating on the fibre. The vapour is produced by directing a high power electron beam onto the end of a solid bar feed stock. Typical deposition rates are 5–10µm per minute. Composite fabrication is usually completed by assembling the coated fibres into a bundle or array and consolidating in a hot press or HIP operation. Composites with uniform distribution of fibre and volume fraction as high as 80% can be produced by this technique.

Liquid state processing

Stir casting: This involves incorporation of ceramic particulate into liquid aluminium melt and allowing the mixture to solidify. Here, the crucial thing is to create good wetting between the particulate reinforcement and the liquid aluminium alloy melt. The simplest and most commercially used technique is known as vortex technique or stir-casting technique. The vortex technique involves the introduction of pre-treated ceramic particles into the vortex of molten alloy created by the rotating impeller. Lloyd (1999) reports that vortex-mixing technique for the preparation of ceramic particle dispersed aluminium matrix composites was originally developed by Surappa & Rohatgi (1981) at the Indian Institute of Science. Subsequently several aluminium companies further refined and modified the process which are currently employed to manufacture a variety of AMCs on commercial scale. Microstructural inhomogeneties can cause notably particle agglomeration and sedimenta- tion in the melt and subsequently during solidification. Inhomogeneity in reinforcement distribution in these cast composites could also be a problem as a result of interaction between suspended ceramic particles and moving solid-liquid interface during solidification. Gene- rally it is possible to incorporate upto 30% ceramic particles in the size range 5 to 100µm in a variety of molten aluminium alloys. The melt–ceramic particle slurry 11 may be trans- ferred directly to a shaped mould prior to complete solidification or it may be allowed to solidify in billet or rod shape so that it can be reheated to the slurry form for further processing by technique such as die casting, and investment casting. The process is not suitable for the incorporation of sub-micron size ceramic particles or whiskers. Another variant of stir casting process is compo-casting. Here, ceramic particles are incorporated into the alloy in the semi solid state.

Infiltration process: Liquid aluminium alloy is injected/infiltrated into the interstices of the porous pre-forms of continuous fibre/short fibre or whisker or particle to produce AMCs. Depending on the nature of reinforcement and its volume fraction preform can be infiltrated,withorwithouttheapplicationofpressureorvacuum.AMCshavingreinforcement volume fraction ranging from 10 to 70% can be produced using a variety of

infiltration techniques. In order for the preform to retain its integrity and shape, it is often necessary to use silica and alumina based mixtures as binder. Some level of porosity and local variations in the volume fractions of the reinforcement are often noticed in the AMCs processed by infiltration technique. The process is widely used to produce aluminium matrix composites having particle/whisker/short fibre/continuous fibre as reinforcement.

Spray deposition: Spray deposition techniques fall into two distinct classes, depending whether the droplet stream is produced from a molten bath (Osprey process) or by continuous feeding of cold metal into a zone of rapid heat injection (thermal spray process). The spray process has been extensively explored for the production of AMCs by injecting ceramic particle/whisker/short fibre into the spray. AMCs produced in this way often exhibit inhomogeneous distribution of ceramic particles. Porosity in the as sprayed state is typically about 5–10%. Depositions of this type are typically consolidated to full density by subse- quent processing. Spray process also permit the production of continuous fibre reinforced aluminium matrix composites. For this, fibres are wrapped around a mandrel with controlledinter fibre spacing, and the matrix metal is sprayed onto the fibres. A composite monotype is thus formed; bulk composites are formed by hot pressing of composite monotypes. fibre volume fraction and distribution is controlled by adjusting the fibre spacing and the number of fibre layers. AMCs processed by spray deposition technique is relatively inexpensive with cost that is usually intermediate between stir cast and PM processes.

Literature review

PAPER TITLE

JOURNAL NO.

COMPOSITION OF METAL ALLOY

MECHANICAL PROPERTIES MEASUREMENT TECHNIQUES

FABRICATION METHOD

APPLICATION OF COMPOSITES

Girisha H.n. , Dr.K.V Sharma

Effect of magnesium on strength and microstructure of Aluminium Copper Magnesium alloy

ISSN 2229-5518

Al4Cu+Mg(.5-2%) subjected to T6 heat treatment for 5hr at 175 degree Celsius.

ALLOY ULTIMATE TENSILE STRENGTH

BHN

As cast

5 hr treatment

As cast

5 hr treatment

AlCu4Mg(0)

103.52

113.94

71.68

89.7

AlCu4Mg(0.5)

106.48

133.61

72.75

91.0

AlCu4Mg1.0

118.74

216.79

89.7 91.3

AlCu4Mg(1.5)

121.09

138.94

89.88

83.2

AlCu4Mg(2.0)

163.48

113.23

89.88

91.0

Tensile and Hardness test as per ASTM standards

Gravity Die Casting

-

AUTHOR NAME

PAPER TITLE JOURNAL NO.


MECHANICAL PROPERTIES

MEASUREMENT TECHNIQUES

FABRICATION METHOD


S.A Hoseini,Khalil Ranjbar,R. Dehmolaei,A.R amirani

Fabrication of Al 5083 surface composites reinforced by CNT and cerium oxide nano particles via friction stir processing

622(2015)725-733

Al5083(Zn-0.061%,Cu-0.06%,Ti-0.04%,Si-0.22%,Cr-0.11%,Fe-0.4%,Mn-0.4%,Mg-4.51%,Al-balance)+CNT/CeO2(volume ratio25-75)

Increase in volume ratio from from 25-75 will increase meachanical properties and corrosion resistance

Tensile Test and Fractography,

-

Friction Stir Casting

In Aerospace industries.

AUTHO PAPER JOUR COMPOSITIO MECHANICAL MEASUR FABR APPLICATION OF

R NAME TITLE NAL NO.

N OF METAL ALLOY

PROPERTIES EMENT TECHNIQUES

ICATION METHOD

COMPOSITES

Pradeep Sharma, Satpal Sharma,Dinesh Khanduja

Production and some properties of Si3N4 reinforced aluminium alloy composites

3(2015)352-359

AA6082(Si-0.7-1.3%,Fe-0.0-0.5%,Cu-0.0.-0.1%,Mn-0.4-1.0%,Mg-0.6-1.2%,Zn-0.0.-0.2%,Ti-0.0.-0.1%,Cr-0.0-.25%,Al-balance)And Si3N4(0-12%)

Hradness increases with increase in % of Si3N4 i.e, from 49.5BHN to 93.5BHN.Reduction in ductility from 8.7 to 4.3 & improved tensile strength from 161.5MPa to 201MPa

-

Reciprocating engine components,turbochargers,bearings etc.

AUTHOR NAME

PAPER TITLE

JOURNAL NO.


MECHANICAL PROPERTIES MEASUREMENT TECHNIQUES

FABRICATION METHOD


Dinesh M. Pargunde,Prof. Gajanan N. Thokal,Prof. Dhanraj P. Tambuskar,Mr. Swapnil,S. kulkarni

Development of aluminium based metal matrix composite (AlSic)

E-ISSN22498944

Optimum ratio is Al-75%SiC-25%

Hardness and impact strength are maximum at optimum ratio.

SiC(%)

Hardness(BHN)

Impact Strength(J)

23 43.73 31.6724 43.73 3325 44.86 35.3326 44.76 35.3327 43.86 34

Normalised Displacement Test

Stir casting

Preparation of material

Placing raw material ina graphite crucible into a muffler furnace

Heating the crucible above the liquids temp.of both materials

Stirring is done to homogenize the microstructure at that temp. and then adding the reinforcement into the molten alloy.

Formula one car brakes, advanced bicycle frames.

AUTHO PAPER TITLE JOURNA COMPOSITION OF MECHANICAL MEASURE FABRI APPLICA

R NAME L NO. METAL ALLOY PROPERTIES MENT TECHNIQUES

CATION METHOD

TION OF COMPOSITES

Dinesh Kumar Koli,Geeta Agnihotri,Rajesh purohit

A review of properties, behavior and processing methods of for Al nano Al203 composites

6(2014)567-589

Al & Al2O3(1-7 vol%) and sintering at 620 degree temp.

Strength increased with 4% volume fraction of particulate.

-

PowderMetalllurgy

Si-7.5wt%Mg-0.38wt%Zn-0.02wt%Cu-0.001wt%Al-balance as matrix matter and then adding Al2O3 as the particulate.

Porosity level increased slightly with increasing particulate content.The yield strength and ductility improved and maximum hardness at 2.5% Al2O3 at 800 degree cast.

-

Casting

Reference-Asavavisithchai, S., Kennedy, A.R., 2006. The effect of Mg addition on the stability of Al–Al2O3 foams made by a powder metallurgy route. Scripta Mater. 54, 1331–1334.

-ASTM Designation: G99-95a, e1, 2000a. Standard test method for wear testing with a pin-on-disk apparatus.

-ASTM Designation: E9-89a, e1, 2000b. Standard test methods of compression testing of metallic materials at room temperature.

-ASTM Designation: E10, e1, 2000c. Standard test method for Brinell hardness of metallic materials.

Daoud, A., Reif, W., 2002. Influence of Al2O3 particulate on the aging response of A356 Al-based composites. J. Mater. Process. Technol. 123, 313–318.

-Dieter, G.E., Bacon, D., 1986. Mechanical Metallurgy. McGraw-Hill,

London.

Hassan, S.F., Gupta, M., 2008. Effect of submicron size Al2O3 particulates on microstructural and tensile properties of elemental Mg. J. Alloys Compd. 457, 244–250.

-Hoseini, M., Meratian, M., 2009. Fabrication of in situ aluminum– alumina composite with glass powder. J. Alloys Compd. 471, 378–

382.

-Mazahery, A., Abdizadeh, H., Baharvandi, H.R., 2009. Development of high-performance A356/nano-Al2O3 composites. Mater. Sci. Eng., A 518, 61–64.

-Naji, H., Zebarjao, S.M., Sajjadi, S.A., 2008. The effects of volume percent and aspect ratio of carbon fiber on fracture toughness of reinforced aluminum matrix composites. Mater. Sci. Eng., A 486, 413–420.

Experimental procedureDetails of apparatus

-Connecting rod is the intermediate link between the piston and the crank. And is responsible to transmit the push and pull from the piston pin to crank pin, thus converting the reciprocating motion of the piston to rotary motion of the crank. Connecting rod, automotives should be lighter and lighter, should consume less fuel and at the same time they should provide comfort and safety to passengers, that unfortunately leads to increase in weight of the vehicle. This tendency in vehicle construction led the invention and implementation of quite new materials which are light and meet design requirements.weight on crankshaft. Application of metal matrix composite enables safety increase and advances that leads to aluminium connecting rods reinforced with steel continuous fibers.

By carrying out these modifications to engine elements will result in effective reduction of weight, increase of durability of particular part, will lead to decrease of overall engine weight, improvement in its traction parameters, economy and ecological conditions such as reduction in fuel consumption and emission of harmful substances into atmosphere.

table-1

Table-2

VOLUME, WEIGHT AND STIFFNESS OF THE CONNECTING ROD.

1. For aluminium 360 2. aluminium 6061-9%SiC-15%fly ash Weight of the connecting rod = 268.1811 Weight of the connecting rod = 151.5555

Deformation = 0.137925 Deformation = 0.034481 Stiffness = weight / deformation Stiffness = weight /

deformation Stiffness = 268.1811/0.137925 Stiffness =

151.5555/0.034481 Stiffness = 1944.39 g/mm Stiffness = 4395.3336

g/m

Conclusion- WEIGHT CAN BE REDUCED BY CHANGING THE MATERIAL OF THE CURRENT AL360 CONNECTING ROD TO HYBRID ALFASIC COMPOSITES.

-THE OPTIMISED CONNECTING ROD IS 43.48% LIGHTER THAN THE CURRENT CONNECTING ROD.

-THE NEW OPTIMISED CONNECTING ROD IS COMPARATIVELYMUCH STIFFER THAN THE FORMER.

Applications of aluminium and composite materials with aluminium base provide design and produce high performance vehicles with safety improvements and improvements of energy efficiency and ecology aspects that are resistant to corrosion and with reduced masses. Composites with aluminium base are usually used for making of engine pistons, cylinders barrel, connection rods, elements of vehicles braking systems, Cardan shafts and so on. By the application of aluminium at vehicle body, indirectly an increase of engine lifetime is done, the same as increase of lifetime of gear box, breaking system, wheels and other vehicle systems.

Future aspectFrom the aspect that over 50 % of global production of composite material with metal matrices is used at automotive industry, the focus of application of this material will be put on cars. Large numbers of car parts are made of composite materials. The ratios of their prices and qualities present main causes for applications of those materials. It is obvious that composite materials with metal matrices are generally used for responsible parts at modern cars.

Engine pistons

Engine pistons operate in very hard dynamical, thermal and mechanical conditions. The pistons are loaded to cyclic mechanical load with frequency of around 100 Hz, so fatigue damages are primarily important. Pistons must provide intimate contacts with cylinders at maximal pressures during expansion periods. Dynamic endurance, high resistance to wear and thermal expansion coefficient are necessary characteristics of materials for cylinders. It is also necessary that pistons can operate at temperatures of around 3000 °C. Due to temperature gradients and thermal cycles, high thermal conductivity must be provided in order to reduce temperatures and thermal impacts.

Breakthrough in the area of aluminium MMC application is done by production of pistons for diesel engines at Toyota car manufacturer [3, 7, 19]. The serial production of those pistons started in Japan at 1983. The materials for the pistons were composite materials with aluminium alloy matrices reinforced by ceramic particles and fibres in order to reduce wear and to improve resistance to material fatigue at high temperatures. Those composites were made by squeeze casting

method. Due to large series in production of over 100.000 items per mount, the produced parts had excellent quality at satisfactory prices.

Metal matrices composites with ceramic reinforcements used for production of pistons have significantly higher resistance to wear in relation to materials used for matrices. Simultaneously, pistons have small values of thermal expansion coefficients that provide use of narrow tolerances, so that it results in increasing of maximal allowed pressures and improved thermal conductivity properties [7]. Lower weights of pistons also have positive influence to beneficial properties of materials in exploitation. Besides that, method of MMC casting is quite simpler than traditional method of piston fabrication. In general, beside higher prices of aluminium materials by units, summary prices of pistons are smaller than pistons made of traditional materials. Large numbers of positive performances of MMC application implicate use of those materials for pistons made. As reinforce materials to metal matrices silicon carbide (SiC) is usually used especially at race cars. The pistons made of MMC are widely used in Asia and West Europe car producers.

Engine piston

Engine cylinders

Wide usage of aluminium alloys for production of engine block is main cause of application of those materials for cylinders. Serial production of cylinder barrel made of aluminium MMC started in 1990. It was used for the first time at 2,3 litre engine of Honda Prelude [7]. Hybrid composite material with aluminium matrix was reinforced by carbon and Al2O3 (12 %Al2O3+9 % carbon) for this application. The cylinders barrels were made by squeeze castings at medium pressure. The example of engine with cylinder barrel made of aluminium MMC .

-Resistance to wear of aluminium MMC is higher than resistance to wear of cast iron. The summary weight of engine block is reduced by 20 % by application of MMC. Besides that, aluminium MMC has higher thermal conductivity and, by that, operating temperature is lower so exploitation period is longer. Thickness of cylinder barrel is smaller than one made of cast iron, so the increase of working volume of exact engine is provided without its redesign.

-The engines with cylinder barrel made of MMC composite are used at Honda S2000 – sport cars, also at Acura NSX cars type and at Porsche Bower motors [3, 7]. The engines at Toyota Celica 2000 cars also have cylinder barrels made of MMC. The cylinder barrels made of aluminium MMC are used, also, at high performances Honda motorbikes. Those materials are produced by powder metallurgy methods.

Engine pushrods

-Aluminium MMC reinforced by fibres is used for production of pushrods of valves at engines. As reinforcing material, fibres of Al2O3 are used, while for the matrix aluminium alloys are used. The first producer of these parts made of MMC is 3M Corporation (Fig. 5). The pushrods of engine valve made of alumina MMC have 25 % higher stiffness to flexion and twice higher absorption capacity than the related parts made of common steel. Due to smaller density and weight, number of rotations can be increased for 200 ÷ 400 1/min without additional dynamic loads. The exploitation period of those pushrods are significantly higher than ones made of steels [14, 16].

Engine connection rod

-By making engine connection rod of aluminium MMC mass reduction of 57 % related to steel one is obtained. By reduction of piston/connection rod mass, vibrations during operation are also reduced. By that, reduction of load at crankshaft and at its bearing is also done, energy losses due to friction are also reduced, the same as engine fuel consumption . It is concluded that reduction of crankshaft by 1 kg caused related reduction of balancing counterweight by 7 kg [14]. As material for making of connection rod, composites with

aluminium matrix reinforced by SiC (Nissan) or Al2O3 (Dupondt, Chrysler) are used [8]. By application of aluminium connection rod, reduction of fuel consumption and improvement of engine power are done with simultaneous increase of its total production cost .

-Further researches of MMC are focused on production of materials that can be used for pistons connecting rods. The prototype of connecting rod made of aluminium MMC . The researches in this area are still in process.

Brake systems

-Due to beneficial characteristics, high resistance to wear and high thermal conductivity, aluminium MMC is used for production of break discs and drums at cars. On the basis of the weight reductions, inertial forces are also reduced, so as summary weight of vehicles and fuel consumptions.

Al-Mg and Al-Si alloys reinforced by ceramic Al-Mg and Al-Si alloys reinforced by ceramic materials such as SiC and Al2O3 are used for production of brake discs and drums [20 ÷ 25]. The technology processes for production of composite materials are different casting

methods, while volumetric share of reinforcing materials is up to 20%. Large number of producers in automotive industry use aluminium MMC for production of brake systems. At Lotus Elise (1996 ÷ 1998) all four sets of brake system are made of MMC. PlymonthPromler rear sets of brake system are made of MMC. Uncontinual reinforced aluminium MMC is used for brake discs of Volkswagen Lupo 3L and Audi A2. Hybrid and electrical vehicles are also equipped by brake systems made of aluminium MMC as Toyota RAV4, Ford Prodigy and General Motors Precept [3, 7, 25]. Brake systems made of aluminium MMC are presented in Fig. 7.

-Brake discs made of uncontinual reinforced aluminium MMC are used at high speed trains in Germany – Inter City Express (ICE). Those brake discs are used at ICE-1 and ICE-2 trains on more than 100 train compositions [7].

-Aluminium MMC is also used at brake systems of race cars. As materials for brake systems of race cars, Al 2124/SiC/25p is used. Braking pads made of MMC are used at Porsche 911. All those composites have ceramic reinforcements

Other applications

MMC with aluminium matrices have very wide area of application. Due to specific characteristics and properties, those materials are used for production of brake calliper assembles, gears, valves, belt pulleys, turbines, turbo-compressors, housings of pumps and supporting parts.

The basic advantages of MMC as materials for machine parts are higher resistance to wear, low value of thermal expansion coefficients and good thermal properties. The prices of MMC are still high, but with decreasing trend due to quantity of produced parts made of those materials.

aluminium based composite materials applied to automotive industry

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