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UAB SCHOOL OF ENGINEERING

The Uses of Metal

Matrix Composites inBi!les

Kerry Bisset

S"#mitte$ to% &r' Cha(la

Abstract:

The "se of metal matrix omposites ha)e #een expan$in* to all $i+erent

appliations inl"$in* rereational "ses' The nee$ for a li*hter !et $"ra#le frame is

nee$e$ for #i!le, an$ the (a! to ma-e these $eman$s possi#le is thro"*h

material alteration' Bi!le frames s(ithe$ to li*ht.(ei*ht al"min"m allo!s to

lo(er the (ei*ht' There (as a nee$ for #etter properties in the #i!le frame, an$


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the material alteration (ent to a metal matrix omposite, (hih the #ase allo! (as

still al"min"m' This allo(e$ for a (ei*ht re$"tion an$ (as a sti+er material that

meet the spei/ations of the appliation'


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Table of ContentsAbstract:''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 0

I. Introduction''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 1

II. The Processing for MMCs in Bicycles''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''2

III. Why are MMCs used in Bicycles''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''3

a' Al"min"m.SiC''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''4

#' Al"min"m.Boron Car#i$e'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''05

IV. Problems ith use of MMCs in Bicycles'''''''''''''''''''''''''''''''''''''''''''''''''''00

V. Conclusions of MMCs in Bicycles''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''06

7I' 8or-s Cite$''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 09


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I. Introduction

Metal matrix omposites ha)e #een inreasin* in pro$"tion in the last 25

!ears' The pro$"tion of metal matrix omposites :MMCs; has #een "se$ in the

lo(er meltin* temperat"re metals #ea"se of the eas! of pro$"tion' One of the

most ommon metals for MMCs is al"min"m' This metal is hosen for its lo( meltin*

point, hi*h stren*th, an$ lo( $ensit! for spei/ (ei*ht appliations' The

reinforement a$$iti)e is selete$ #! the (etta#ilit! an$ the mo$"l"s of the

reinforin* a$$iti)e :Cha(la


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"n$erstan$in* of (hat fail"res that o"r in@"ene the hoie of the material' In

*eneral, as the maxim"m loa$in* pre$ite$ thro"*h #"-lin* an$ !iel$in* $o not

s"**est re*"lar fail"res' The main a"ses of fail"res are a"se$ #! fati*"e, ra-

*ro(th, material $efets, or orrosion :Reina, 6553;' Usin* /nite element anal!sis

:FEA;, the strains in a #i!le frame an #e seen in Fi*"re 6' The FEA sim"lation

sho(s that the material nee$s to #e a#le to ha)e a stron* oint onnetion' The

frame also nee$s a material (ith a *reat sti+ness to pre)ent the (arpin* of the

frame' 8ith erami reinforements, metal matrix omposites allo( for the a$$ition

sti+ness nee$e$ to impro)e the #i!le frame'

Figure #. Maimum rincile strains for s(uare element model in a nite elementanal)sis !*eina, #$$+%.

II. The Processing for MMCs in Bicycles

The rise in #i!lin* enth"siast has reate$ $eman$ for a #etter #i!le (ith

hi*her performane str"t"re' The properties of fati*"e, stress frat"rin*, an$

str"t"ral shatterin* are "s"al onse="enes of the impat fores seen in more an$

more ro"*h terrain #i-in*, espeiall! on the (heels of the #i!le' There are se)eral

sol"tions to ma-in* the #i!le more protete$ a*ainst these fail"res that ha)e

#een teste$% omposite pol!meri /#er.resin matrix rims, others alter the tr"ss st!le

of the rim pro/le, an$ "sin* metal matrix omposites' The omposite pol!meri


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/#er.resin matrix rims a#sor# the sho-, lo(er the (ei*ht, an$ ha)e the ran*e in

stren*ths to meet the "stomers re="irement' The $ra(#a- to this material is the

#ra-e to rim interfae $oes not reate s"ient #ra-in* po(er an$ the (heels

onstantl! nee$ to #e reali*ne$ #ea"se of the lo( sti+ness' The $esi*n of the tr"ss

$esi*n allo(s for a hi*her sti+ness, #"t reate$ stress si*hts that a"se$ more

frat"res' Al"min"m metal matrix omposites o+er the i$eal propert! set for #i!le

rims'

There are other MMCs that an #e fo"n$ in #i!les to ma-e "p the frame or

the (heels' These t(o omponents are the most ommon to #e ma$e "p of MMCs'

The matrix of MMCs ommonl! "se$ in #i!les are al"min"m, ma*nesi"m, or

titani"m' Eah on has their o(n spei/ appliation' The al"min"m is the most

ommon an$ (i$el! pro$"e$' Ma*nesi"m MMCs are fo"n$ in rae #i-es (here the

li*htest (ei*ht helps the raer' Titani"m MMC #i!les are fo"n$ for the ro"*hest

on$ition for #i!les' The a$$iti)e materials $i+er from ompan! to ompan!' The

most ommon reinforin* a$$iti)es are al"mina, #oron ar#i$e, an$ other ar#i$es'

Al"min"m is a li*ht(ei*ht an$ easil! $eforma#le material, #"t it is also a

mo$eratel! #rittle material (ith lo(er than a)era*e resistane to a#rasion'

Al"min"m MMCs are ommeriall! a)aila#le for extr"sion' These #illets are #ein*

pro$"e$ "sin* po($er metall"r*!, spra! an$ astin*' Al"min"m MMCs ha)e an

e)en $istri#"tion of f"ll! (ette$ partiles in the matrix'

MMCs #i!les an #e t"ne$ for some of the most extreme enth"siast' 8hile

the #i!les *et more t"ne$ for the ri$er the ost of the #i!le omes to a pea-'

MMCs are onl! seen in top en$ #i!les #ea"se for e)er!$a! mass transit #i!les

these stren*th re="irements are not neessar!' These #i!les also ost more

#ea"se of the proessin* nee$e$ to ma-e the #i!les'


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The extr"sion of al"min"m matrix omposites ho( most of the frame is

ma$e' The in*ots tho"*h an #e pro$"e$ from t(o metho$s% astin* an$ sinterin*'

The metho$ to form most metal matrix omposites for #i!les is to melt an

al"min"m in*ot, a$$ the erami reinforement, stir, an$ ast into an extr"sion

#illet' This proess an #e seen in Fi*"re 1' The t(o important parts of this proess

are the stirrin* of the molten omposite to *et a homo*eno"s $istri#"tion of the

reinforement phase an$ the soli$i/ation of the #illet' The importane of the

homo*eno"s $istri#"tion of the reinforin* phase has a *reat e+et on the

mehanial properties' The soli$i/ation of the in*ot is important #ea"se of the

thermal stresses *enerate$' The metal (ill ha)e a thermal on$"ti)it! an$ in

*eneral a hi*her thermal expansion than the erami phase' This thermal mismath

(ill reate a stress an$ if hille$ to ="i-l! the erami phase (ill #e frat"re$'

Figure . -chematic of the uralcan rocess that is t)ical for MMCs !Chawla /Chawla, #$$0%.


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III. Why are MMCs used in Bicycles

Bi!les are *enerall! ma$e "p of )er! ommon material s"h as steel an$

al"min"m' These are still ma-e "p the maorit! of #i!les fo"n$ to$a!' These

materials are ommon #ea"se the! ha)e #een aro"n$ lon*er, ha)e #een st"$ie$,

an$ the proess to ma-e these materials is in$"strialiDe$' The materials nee$e$ to

f"rther the a$)anement of #i!les are more omplex than "st plain ar#on steel'

Composites ha)e o+er the f"rther a$)anement of materials s"h as metal

reinfore$ omposites' This is the most ommon t!pe of MMC in #i!les is

al"min"m reinfore$ omposite'

As pre)io"sl! $enote$ the main plaes that "se MMCs in #i!les are in the

frame an$ in the rim of the (heels' There is a *reat $i+erene in the t(o in the t(o

parts an$ that is ho( the parts interat (ith the other feat"res on the #i!le' The

frame has to *o "n$er some oinin* operation (hile the rims rel! on mehanial

onnetions to interat (ith the rest of the #i!le' The metho$ of oinin* ommonl!

seen in #i!les is (el$in*, ho(e)er this is not the ase in MMCs' The most ommon

metho$ to oin MMC #i!le frames is thro"*h an a$hesi)e #on$' This allo(s for

interatomi attahments (itho"t the $ama*in* e+ets of (el$in*' In pro$"tion

these a$hesi)e frames ta-e a shorter amo"nt of time to prepare than (el$e$

frames, in a$$ition to the ne( a$hesi)es ha)in* similar mehanial properties to

(el$in*'

The $e)elopment in MMCs #i!les is mainl! in the proessin* of the MMCs,

espeiall! in the al"min"m matrix omposites' Al"min"m is one of the easier metals

to ma-e into a omposite #ea"se of the lo(er meltin* temperat"re an$ the metals

@"i$it! so that it (ets the reinforin* phase' One of the maor a$)anements in

omposites is the pretreatment of the reinforement phase an$ the monitorin* of


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the siDe of the reinforin* phase :Cha(la


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Figure . &ensile test data showing the variance in the tensile testing data with thearticle si2e var)ing !Chawla ". "., #$1#%.

One of the most $esri#e$ allo!s "se$ in MMCs is #i!les is al"min"m (ith

silion ar#i$e :SiC; parti"late reinforement' The amo"nt of reinforement an$

parti"late siDe is "p to the ompan! ma-in* the #i!le' Fi*"re sho(s al"min"m

(ith 15 perent SiC partiles that are "se$ in #i!le frames :Moore, 0??4;'


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Figure 3.4tical micrograh of olished 5l-iC cross section. -iC articulate hase

!dark contrast% and 5l metal6matri !white contrast% ll orosit) of -iC reform

comletel) to form a full) dense 5l-iC6comosite microstructure :Ohionero,

6552;.

#' Al"min"m.Boron Car#i$e

8hile silion ar#i$e is the most ommon partile in MMCs "se$ for #i!les,

#oron ar#i$e is also another parti"lar reinforement that (ill #e examine$' Boron

ar#i$e is the har$est material pro$"e$ #! tonna*e :USCalifornia >atent No'

2,?45,56, 0???;' The fa#riation to pro$"e the #oron ar#i$e MMC is $i+erent

than that of other t!pial MMCs #ea"se it is not ma$e thro"*h molten proess' The

#oron ar#i$e MMC is pro$"e$ thro"*h po($er metall"r*! then s"#ete$ to hi*h

press"re to on)ert the elements into in*ots' These in*ots an #e f"rther proess

thro"*h extr"sion to ma-e the shape neessar! for #i!les' The a)era*e siDe of

these partiles is aro"n$ 4'9 mirons, an$ is *enerall! aro"n$ 06 #! (ei*ht' The

stren*th of #oron ar#i$e parti"late MMC is similar to that of hromol! steel

:USCalifornia >atent No' 2,?45,56, 0???;' One of the #ene/ts of the #oron ar#i$e

MMC is the rea$iness for (el$in*' An example of #oron ar#i$e in al"min"m an #e

seen in Fi*"re 3' This mirostr"t"re sho(s the parti"late reinforement that has

#een "se$ in #i!le fa#riation'
http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582http://www.pcb007.com/pages/zone.cgi?a=63582


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Figure +. Micrograh of aluminum matri with boron carbide articulatereinforcement !7- 8atent 9o. :,$$,#0, #$11%.

Boron /#ers an$ parti"lates are "se$ #ea"se of the hi*h stren*ths that are

o#taine$' These properties, as an #e ima*ine$, are onl! nee$e$ for the most

extreme ir"mstanes for #i!les' The stren*th of the #orsi /#ers an #e seen in

Fi*"re 4' The stren*th to (ei*ht ratio, spei/ stren*th, for these omposites is also

)er! hi*h (hih means less material has to #e "se$' The spei/ stren*ths for

)ario"s material an #e seen in Fi*"re ?'


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Figure :. -trengths of various aluminum allo)s and comosites !5skeland, Fula), /;right, #$11%.

Figure


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IV. Problems ith use of MMCs in Bicycles

A ommonl! fo"n$ erami partile in al"min"m MMCs is silion ar#i$e' In

these parti"lar MMCs, the silion ar#i$e is thermo$!namiall! "nsta#le in the

molten al"min"m, (hih lea$s to the formation of al"min"m ar#i$e' This formation

of al"min"m ar#i$e at the interfae is #elie)e$ to ha)e a ne*ati)e e+et on the

mehanial properties of the omposite' This $etriment is #ea"se of the interfae

stren*th an$ omposition' This reation ma-es this ommon omposite more

$i"lt to o#tain an$ th"s a"sin* a prie inrease #ea"se of the aref"l

proessin* tehni="es that m"st #e pratie$ :USCalifornia >atent No' 2,?45,56,

0???;'

oinin* a material is a r"ial part of ma-in* a #i!le frame' The most

ommon an$ relia#le (a! to oin materials in a #i!le frame is thro"*h (el$in* the

frame piees to*ether' The (el$in* proe$"re has a maor impat on the materials

mirostr"t"re an$ therefore impats the properties of the material at that point'

The mirostr"t"re of a MMC is s"#ete$ to *rain o)er enlar*ement :Moore, 0??4;'

This *rain enlar*ement is seen in all materials, #"t the loal *rain *ro(th aro"n$

the reinforin* partiles'

There are man! proessin* tehni="es for MMCs, #"t for the soli$i/ation of

the in*ots to *o to the $i+erent proesses s"h as a fo"n$r! or an extr"sion plant'

Extr"sion of these in*ots an a"se a pro#lem #ea"se of the reinforin* phase

a"sin* faster $ie (ear, in #oron ar#i$es MMCs the extr"sion $ie is ma$e "p of

titani"m $i#ori$e' The main pro#lem (ith metal matrix omposites in #i!les is the

ost, an$ (ith t"n*sten an$ titani"m $ies nee$e$ for the MMCs raises the ost to

ma-e ommon items s"h as #i!les o"t of the ran*e for t!pial ons"mers'


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V. Conclusions of MMCs in Bicycles

Bi!les ha)e #een ma$e o"t of #asi materials s"h as steels an$ al"min"m

in the past' The re)ol"tions is metal matrix omposites ha)e ma$e an impat on

most appliations, #"t no( it spans to rereational "ses' Bi!les enth"siast re="ire

a #i!le that (ill (ithstan$ the most ri*oro"s ir"mstanes' MMC #i!le o+er

more t"ne$ properties to allo( for the more extreme ases' The parts on the #i!le

that experiene the most stress are the rim of the (heels an$ the #i!le frames'

These are "s"all! ma$e from al"min"m, an$ no( an #e ma$e (ith al"min"m

matrix omposites'

These #i!les are more expensi)e than re*"lar #i!les ha)e easier

proessin* tehni="es an$ there less $eman$ for MMC #i!les than re*"lar

#i!les (hih inreases pro$"tion ost' MMC #i!les an #e pro$"e$ in man!

metho$s, #"t the metho$s inl"$e re$"in* inter.$en$riti triple points, (hih are a

maor start point for ra-s' The spei/ MMCs pertainin* to those "se$ in #i!les

a$$ sti+ness, fati*"e life, an$ stren*th to the frame an$ the rims' There are also

thermo$!nami reations that m"st #e onsi$ere$ (hen ma-in* metal matrix

omposites #ea"se of the (ea-er phase$ that o"l$ #e forme$ if the proessin* is

prepare$ (ron*'

There are se)eral $ra( #a-s to pro$"in* MMCs% oinin* iss"es, ost, an$

onsisten!' 8hile a$hesi)e ha)e #eome stron*er, the a$hesi)es nee$e$ for the

MMC #i!les are not ="ite as stron* as (el$in* oint' MMCs annot #e (el$e$

#ea"se of their mirostr"t"re an$ the reinforin* phase' The mirostr"t"re of

MMC is har$ to ontrol thro"*h the sinterin* proess, #"t the amo"nt an$ t!pe of

reinforin* phase allo(s for the material to #e nearl! anisotropi'


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7I' 8or-s Cite$

As-elan$, &' R', F"la!, >' >', 8ri*ht, 8' ' :6500;' &he -cience and =ngineering of

Materials.Stamfor$% Cen*a*e Learnin*'

Car$en, R' A' :0???;'7->California 8atent 9o. ,

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