j m a t e r r e s t e c h n o l . 2 0 1 4;3(1):916

Available online at www.sciencedirect.com

www. jmrt .com.br

Origina

Corro Mhybrid composites reinforced with rice husk ash and siliconcarbide

Kennetha Departmenb School of Mc Departmen

a r t i c

Article histor

Received 3 S

Accepted 10

Available on

Keywords:

AlMgSi all

composites

Rice husk as

Silicon carb

Corrosion

Stir casting

Wear

1. Int

The develobased wastmore conve

CorresponE-mail: k

2238-7854/$ http://dx.do Kanayo Alanemea,, Tolulope Moyosore Adewaleb, Peter Apata Olubambic

t of Metallurgical and Materials Engineering, Federal University of Technology, Akure, Nigeriaaterials, Faculty of Engineering and Physical Sciences, University of Manchester, Manchester, United Kingdomt of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria, South Africa

l e i n f o

y:

eptember 2013

October 2013

line 23 November 2013

oy based hybrid

h

ide

a b s t r a c t

The corrosion and wear behaviour of AlMgSi alloy matrix hybrid composites developed

with the use of rice husk ash (RHA) and silicon carbide (SiC) particulates as reinforcements

were investigated. RHA and SiC mixed in weight ratios 0:1, 1:3, 1:1, 3:1, and 1:0 were utilized

to prepare 5, 7.5 and 10 wt% of the reinforcing phase with Al Mg Si alloy as matrix using

double stir casting process. Open circuit corrosion potential (OCP) and potentiodynamic

polarization measurements were used to study the corrosion behaviour while coefcient of

friction was used to assess the wear behaviour of the composites. The corrosion and wear

mechanisms were established with the aid of scanning electron microscopy. The results

show that the effect of RHA/SiC weight ratio on the corrosion behaviour of the composites

in 3.5% NaCl solution was not consistent for the different weight percent of reinforcement (5,

7.5, and 10 wt%) used in developing the AlMgSi based composites. It was evident that for

most cases the use of hybrid reinforcement of RHA and SiC resulted in improved corrosion

resistance of the composites in 3.5% NaCl solution. Preferential dissolution of the more

anodic AlMgSi alloy matrix around the AlMgSi matrix/RHA/SiC particle interfaces was

identied as the primary corrosion mechanism. The coefcient of friction and consequently

the wear resistance of the hybrid composites were comparable to that of the AlMgSi alloy

matrix reinforced with only SiC.

2013 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier

Editora Ltda. All rights reserved.

roduction

pment of Aluminium based composites using agro-es as sole or complementary reinforcement to thentional reinforcing materials such as alumina and

ding author.alanemek@yahoo.co.uk (K.K. Alaneme).

silicon carbide is attracting much attention from researchers[1,2]. Aluminium based metal matrix composites (MMCs) arehighly acclaimed for the attractive property combinationswhich they possess, making them very popular and top choicecandidate material for a wide range of engineering appli-cations [3]. The properties of aluminium matrix composites

see front matter 2013 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda. All rights reserved.i.org/10.1016/j.jmrt.2013.10.008l Article

sion and wear behaviour of Al gSi alloy matrix

10 j m a t e r r e s t e c h n o l . 2 0 1 4;3(1):916

Table 1 Elemental composition of AlMgSi alloy.

Element Si Fe Cu Mn Mg Cr Zn Ti

wt% 0.3961 0.0302 0.0202 0.0125

Element Li Na V Al

wt% 03 0.0000 0.0009 0.0027 98.88

(AMCs) whare: high srosion resishigh tempemal managbased matother commmagnesium[7]. They cniques adoCurrently, derived frobased matnut shell amerated adand amongneering apof materiaaccommodmaterials.

The devAMCs newlreinforcingis highly imof materialand limits based wastate materiawith the usthe resultscal behavioused as hybof corrosionconsistent erties [15].

Corrosioacknowledas shown contradictiAMC systebehaviour opart of asseand suitabof paramouagro wastedata are cucorrosion. Wdeveloped consideredforced withapplication

re is currently no work available which has studiedrrosion and wear behaviour of AlMgSi alloy matrixsites reinforced with rice husk ash and silicon carbide.terest in studying the corrosion and wear behaviour isted by the promising mechanical properties of theseSi arableess

s [20erstaar AMldingHA

Ma

Ma

Si agatiocal cis (Taelecs to be witsk an asg ofing p

wan th

Co

lMgC weantie (SiCons

2

ound0.4002 0.2201 0.008 0.0109

Ni Sn Pb Ca Cd

0.0101 0.0021 0.0011 0.0015 0.00

ich have been explored for varied technical usespecic strength and stiffness, good wear and cor-tance, low thermal coefcient of expansion, goodrature mechanical properties, and excellent ther-ement potentials among others [46]. Aluminiumrices are also noted to be the cheapest amongon metallic matrix materials (copper, titanium,) for metal matrix composites (MMCs) productionan also be processed easily using similar tech-pted for the production of metals and alloys [8].AMCs are being reinforced using waste productsm industrial processes (red mud, y ash) and agroerials (rice husk ash, bamboo leaf ash, groundsh, bagasse, among others) [9,10]. All the enu-vantages have made AMCs become very popular

top choice materials for a wide range of engi-plications by virtue of its excellent combinationl properties, ease processing, reduced cost, andation of waste materials as reinforcement resource

elopment of reliable material property database fory developed with the use of agro wastes as hybrid

materials (to either alumina or silicon carbide)perative. This is of vital importance in the area

s selection to determine the most suitable areasof application of these AMCs reinforced with agroes. To this end, there have been efforts to gener-l properties data for a number of AMCs developede of agro waste based reinforcements [1113]. From

generated, a fairly consistent trend in mechani-ur has been observed for the different agro wastesrid reinforcements in AMCs [10,14]. But in the case

and wear properties, the results have not been asas the observations recorded for mechanical prop-

n behaviour of AMCs in particular has beenged to be difcult to comprehensively predictby the wide variation and not too infrequentng results reported by researchers for differentms [1618]. A measured forecast of the corrosionf AMCs in different environments is very helpful asssments required in establishing its performance

ility in a number of service environments. This isnt importance in AMCs developed with the use of

Thethe cocompoThe inmotivaAlMgcompatoughnpositein undpeculiin buialloy/R

2.

2.1.

AlMginvestichemianalyswere spositecarbidrice hupositioburninfollownesiumbetwee

2.2.

The Aand SiThe qucarbidment c

Table

Comp

s as hybrid reinforcements, since little corrosionrrently available to understand its mechanisms ofear assessments are also very crucial where AMCs

with the use of hybrid reinforcements are to be as replacement for the conventional AMCs (rein-

Silicon carbide or alumina solely) for tribologicals [19].

Silica (SiO2Carbon Calcium oxMagnesiumPotassium HaematiteOthers lloy based hybrid composites which have shown strength characteristics and improved fractureover the single reinforced AlMgSi alloy/SiC com-]. The output from this research will be helpfulnding the corrosion and wear behaviour of theseCs. It would also serve as resource information

a database of material properties for AlMgSiSiC hybrid composites.

terials and methods

terials

lloy was selected as aluminium alloy matrix for then. The alloy was obtained in form of billets and itsomposition determined using spark spectrometricble 1). Silicon carbide (SiC) and rice husk ash (RHA)ted for use as hybrid reinforcement for the com-e developed. For this purpose high purity siliconh average particle size of 28 m was procured. Thesh (with mesh size under 50 m and chemical com-

presented in Table 2) was prepared from complete the rice husks, thermal processing, and sievingrocedures in accordance with Alaneme [10]. Mag-s selected as wetting agent to improve wettabilitye AlMgSi alloy and the reinforcements.

mposites production

Si alloy matrix composites reinforced with RHAre produced using double stir casting process [21].tative amounts of rice husk ash (RHA) and silicon) required to produce 5, 7.5, and 10 wt% reinforce-

isting of RHA and SiC in weight ratios 0:1, 1:3, 1:1,

Chemical Composition of the Rice Husk Ash.

/element (constituent) Weight percent) 91.564.8

ide CaO 1.58 oxide, MgO 0.53oxide, K2O 0.39, Fe2O3 0.21

0.93

j m a t e r r e s t e c h n o l . 2 0 1 4;3(1):916 11

3:1, and 1:0, respectively, were initially determined. In orderto eliminate dampness in the reinforcements and improvewettability with the molten AlMgSi alloy, the rice husk ashand silicon carbide particles were preheated in an oven at atemperature of 250 C. A gas-red crucible (tted with a tem-perature probe) was used to melt the AlMgSi alloy billetscompletely by ring to a temperature of 750 30 C (above theliquidus temperature of the alloy). The molten liquid alloywas then allowed to cool to a semi solid state at a temper-ature of about 600 C before charging in the preheated ricehusk ash and SiC particles (along with 0.1 wt% magnesium).Manual stirring of the slurry was performed at this tempera-ture (600 C) for 510 min. The composite slurry was afterwardssuperheated to 800 50 C and a second stirring performedusing a mechanical stirrer. The stirring was performed at aspeed of 400 rpm for 10 min before casting into prepared sandmoulds inserted with metallic chills. Table 3 presents thedesignations used to represent each grade of the compositesproduced.

2.3. Corrosion test

The corrosion behaviour of the composites produced wasinvestigated in 3.5% NaCl solution at room temperature (25 C)using potentiodynamic polarization electrochemical meth-ods. A Princeton applied research Potentiostat (VersaSTAT 400)with versaSthe corrosioa three-eleple as the wreference eing electrodwire to oneing tape, asurfaces ofbide paper

ASTM [22] standard. Afterwards, the samples were washedwith distilled water, degreased with acetone and dried in air.Open-circuit corrosion potential (OCP) measurements werecarried out in a separate cell for 120 min while Potentiody-namic polarization measurements were performed using ascan rate of 1.6 mV/s at a potential initiated at 200 mV to+1500 mV. After each experiment, the electrolyte was replaced,while the test samples were polished, rinsed in water andwashed with acetone to remove the products that might haveformed on the surface which could affect the measurement.Three repeat tests were performed for each grade of compositeproduced to guarantee reproducibility and repeatability of testresults that were actually observed to be good as there wereno signicant differences between results from triplicates.

2.4. Wear test

The wear behaviour of the composites produced was testedusing a CETR UMT-2 Tribometer. A load of 25 N was used for1000 s, at a frequency of 5 Hz; and the coefcient of frictionwith time for each grade of composite recorded.

2.5. Scanning electron microscopy (SEM)

The corrosion and wear mechanisms of the composites wereestablished by scan electron microscopic (SEM) analysis ofthe surface morphology of the test samples. A JSM 7600F

ra-hcope

Re

Ele

riatisites

Table 3 omp

Sample des

A0

B1 B2 B3 B4 B5

C1 C2 C3 C4 C5

D1 D2 D3 D4 D5 TUDIO electrochemical software was utilized forn studies. The experiments were performed usingctrode corrosion cell set-up comprising the sam-orking electrode, saturated silver/silver chloride aslectrode, and platinum as counter electrode. Work-es were prepared by attaching an insulated copper

face of the sample using an aluminium conduct-nd cold mounting it in resin. Prior to testing, the

the samples were wet ground with silicon car-s from 220 down to 600 grade in accordance with

Jeol ultmicros

3.

3.1.

The vacompo

Corrosion potentials and corrosion current densities of the c

ignation Composition weight ratio of RHA:SiC

0 wt%

5 wt%0:1 1:3 1:1 3:1 1:0

7.5 wt%0:1 1:3 1:1 3:1 1:0

10 wt%0:1 1:3 1:1 3:1 1:0 igh resolution eld emission gun scanning electron (FEG-SEM) was utilized for the microscopy studies.

sults and discussion

ctrochemical behaviour

on in the open circuit potentials of the produced exposed to 3.5% NaCl solution is presented in

osites produced.

Ecorr (V) Icorr (A/cm2)

807.772 0.819

794.939 1.754808.280 0.542801.970 0.945710.055 0.415765.650 3.812

758.550 4.261754.751 7.103808.853 7.837822.612 2.706780.424 0.940

773.265 0.901805.241 4.329814.855 2.345821.102 5.978760.232 2.076

12 j m a t e r r e s t e c h n o l . 2 0 1 4;3(1):916

0

0

-0,88

-0,86

-0,84

-0,82

-0,8

-0,78

-0,76

-0,74

-0,88

-0,82

-0,86-0,84

-0,8-0,78-0,76-0,74-0,72

-0.7

-0,88

-0,82

-0,86-0,84

-0,8-0,78-0,76-0,74-0,72

-0.7a

b

c

Pote

ntia

l (V)

Pote

ntia

l (V)

Pote

ntia

l (V)

0

Fig. 1 Varthe AlMgRHASiC rereinforcem3.5% NaCl

Fig. 1. It isprole of thment, that this series to be B1 (th5 wt% SiC) tion of OCPis typical olm formasive envirothe compoAlMgSi c

3:1) had the highest open circuit potential in comparison withthe other c

st tholutis confted re oA0). nce

comts ofSiCer O2000 4000

Time (s)

A0 B1 B2 B3 B4 B5

6000 8000

the leaNaCl spositeare shiing moalloy (and hetion inamounof RHAof highA0 C1 C2 C3 C4 C5

2000 4000

Time (s) 6000 8000

A0 D1 D2 D3 D4 D5

1000 2000 3000 4000 5000 6000 7000 8000

Time (s)

iation of the open circuit potential with time forSi based composites containing (a) 5 wt%inforcement, (b) 7.5 wt% RHASiCents, and (c) 10 wt% RHASiC reinforcement; insolution.

observed from Fig. 1(a), which presents the OCPe composites containing 5 wt% RHASiC reinforce-the open circuit potentials for all the composites inuctuates continuously. The exception is observede single reinforced AlMgSi composite containingwhich had a fairly stable OCP prole. The uctua-

values in the manner observed in these compositesf materials systems undergoing repeated passivetion and breakdown due to exposure to a corro-nment [15]. On observation of the OCP proles ofsites in this series, it is noted that B4 (the hybridomposite containing RHA and SiC in weight ratio

RHA contement. By cand C3 (conrespectivelsingle reinfAlMgSi acomposite tendency tthe single rcontainingit is the coSiC (D1 andand the hyratio 1:3) ththe other c

The potposites in more thoroFig. 2 showlar polarizacorrosion ptinct for anwhich prescurrent dewas obtainpotentials compositesin the weigweight ratithe OCP cudensity (IcoFig. 3. In trent densit(B series) w10 wt% RHA5 wt% RHAlower corroparison wiRHASiC respecimen Band SiC indensity indtance. Thisthe OCP vathat the oting RHA analso had lowomposite grades. This suggests that B4 will haveermodynamic tendency to corrode in the 3.5 wt%on. It also appears that the OCP proles of the com-taining higher weight ratios of RHA (B3, B4, and B5)to higher values in comparison with those contain-f SiC (B1, and B2) and the unreinforced AlMgSiThis connotes a higher thermodynamic stabilitya lesser tendency to corrode in 3.5 wt% NaCl solu-parison with the composite grades containing less

RHA. For the composite grades containing 7.5 wt% reinforcing phase, there was no clear advantageCP values for the composite grades with higher

nt as observed in the case of the 5 wt% reinforce-ontrast, it is noted that the hybrid composites C2taining RHA and SiC in weight ratios of 1:3 and 1:1,y) had higher OCP values in comparison with theorced composites (C1 and C5), and the unreinforcedlloy (A0). This again shows that some of the hybridgrades in this series have a lower thermodynamico corrode in the NaCl solution in comparison witheinforced composites. However for the composites

10 wt% RHASiC reinforcement, it is observed thatmposite grades containing higher weight ratios of

D2 which are respectively the single reinforcedbrid composite containing RHA and SiC in weightat had higher values of OCP in comparison with

omposite grades in this series.entiodynamic polarization curves for the com-3.5% NaCl solution (Fig. 2) helped in analysingughly the corrosion behaviour of the composites.s that the composites generally displayed simi-tion curves and passivity characteristics. But theotentials (Ecorr) of the composites were clearly dis-d dened in the ranges of 0.83 to 0.71 V. Table 3ents the corrosion potential (Ecorr) and corrosionnsity (Icorr) data of all the composites produceded from Fig. 2. It is seen clear that the corrosion(Ecorr) and corrosion current density (Icorr) of the

did not follow a consistent trend with variationht percent of reinforcement phase and RHA/SiC

os of the composites produced as was the case withrves (Fig. 1). The scatter in the corrosion current

rr) of the composites is better appreciated fromhis gure, it is observed that the corrosion cur-ies of the composites with 5 wt% reinforcementere averagely lower than that of the 7.5 wt% andSiC reinforced composites. This indicates that theSiC reinforced AlMgSi based composites havesion susceptibility in 3.5% NaCl solution in com-th the higher reinforcement grades. For the 5 wt%inforced composite series, it is further noted that4 (the hybrid AlMgSi composite containing RHA

weight ratio 3:1) had the least corrosion currenticating that it has the overall best corrosion resis-

observation is consistent with the results fromlues (Fig. 1a) discussed earlier. It is also observedher hybrid composite grades B2 and B3 (contain-d SiC in weight ratios of 1:3 and 1:1, respectively)er corrosion current densities in comparison with

j m a t e r r e s t e c h n o l . 2 0 1 4;3(1):916 13

-0.6

-0.65

-0.7

-0.75

-0.8

-0.85

-0.9

-0.95

Pote

ntia

l (v)

-1

-1.05

-0.6

-0.65

-0.7

-0.75

-0.8

-0.85

-0.9

-0.95

Pote

ntia

l (v)

-1

-1

-1.05

-0.6

-0.65

-0.7

-0.75

-0.8

-0.85

-0.9

-0.95

Pote

ntia

l (v)

-1.05

1.00E-1

1.00E-0

1.00E-1

a

b

c

Fig. 2 PotAlMgSi breinforcem10 wt% RHA

the single corrosion cwith 7.5 wtincreases wcorrosion cweight ratiresulted incompositeswas no coh

8

7

6

5

4

3

2

1

0A

/cm

2 )3 1.00E-10 1.00E-07 1.00E-04 1.00E-01

Corro

sion

curre

nt d

enist

y (ACurrent density (A/cm^2)

Current density (A/cm^2)9 1.00E-07 1.00E-05 1.00E-03 1.00E-01

Current density (A/cm^2)

A0 D1 D2 D3 D4

A0

A0 B1 B2 B3 B4 B5

C1 C2 33 C4 C5

4 1.00E-12 1.00E-10 1.00E-08 1.00E-06 1.00E-04 1.00E-02 1.00E+00

entiodynamic polarization curves for theased composites containing (a) 5 wt% RHASiCent, (b) 7.5 wt% RHASiC reinforcements, and (c)SiC reinforcement; in 3.5% NaCl solution.

reinforced grades B1 and B5 which had higherurrent densities. In the case of the composites% reinforcement, the corrosion current densityith increase in the RHA weight ratio attaining peakurrent density for specimen C3 (which has RHA:SiCo of 1:1). Further increase in the RHA weight ratio

decrease in the corrosion current density. For the containing 10 wt% RHASiC reinforcement, thereerent trend in the corrosion behaviour (corrosion

Fig. 3 Varsolution fo

current deRHA/SiC wsity values having 7.5 of RHA/SiCweight perdevelopingthat for mand a cheapproperties

Secondathe corrosifor all themore anodthe AlMgtative SEM in Fig. 4 conism. The such as reinmechanicadislocationmonly obsein electrochand the ma

3.2. We

The variatiposites progrades conobserved thweight ratiparison wihybrid comand SiC wecient of fricompositesite containcomposite addition oftary reinfordoes not dcompositesthe highest0 B1 B2 B3 B4 B5 C1 C2

CompositesC3 C4 C5 D1 D2 D3 D4 D5

iation of corrosion current density in 3.5% NaClr all the AlMgSi based composites produced.

nsity variation) with respect to changes in theeight ratio. However the corrosion current den-were averagely lower than that of the compositeswt% RHASiC reinforcement. Although the effect

weight ratio was not consistent for the differentcent of reinforcement (5, 7.5, and 10 wt%) used in

the AlMgSi based composites, it was very clearost cases the use of hybrid reinforcement of SiC

complement RHA does not degrade the corrosionof the composites in 3.5% NaCl solution.ry electron imaging of all the composites afteron test indicates that the corrosion mechanism

composites was preferential dissolution of theic AlMgSi alloy matrix which occurs aroundSi matrix/RHA/SiC particle interfaces. Represen-images of some of the composites are presentednrming the afore-mentioned corrosion mecha-presence of physical or chemical heterogeneitiesforcement/matrix interface, defect, intermetallic,

lly damaged region, grain boundary, inclusion, or is responsible for the localized corrosion com-rved in MMCs [23,24]. This is due to the differenceemical potentials between these heterogeneitiestrix which is often more anodic [18].

ar behaviour

ons of coefcient of friction with time for the com-duced are presented in Fig. 5. For the compositetaining 5 wt% RHASiC reinforcement (Fig. 5a), it is

at the hybrid composite B2 (which has RHA and SiCo of 1:3) had the least coefcient of friction in com-th the other composites in this series. The otherposite compositions B3 and B4 (which have RHAight ratios of 1:1 and 3:1, respectively) had coef-ction comparable to that of the single reinforced

B1 (single reinforced AlMgSi matrix compos-ing SiC) and B5 (single reinforced AlMgSi matrixcontaining RHA). This is a clear indication that the

low cost agro waste product, RHA, as complemen-cement to SiC in AlMgSi alloy based compositesegrade the wear resistance characteristics of the. The unreinforced AlMgSi alloy, as expected, had

coefcient of friction. For the AlMgSi alloy based

14 j m a t e r r e s t e c h n o l . 2 0 1 4;3(1):916

a

b

c

Fig. 4 Somcorroded sthe electroAlMgSi/5(C3), and (c

compositesobserved thcontain RHtively) hadreinforced forcement,

0.5aCOF

0.4

0.3

0.2

0.1

0

-0.1

-0.2e representative SEM photomicrograph of theurfaces of the AlMgSi based composites afterchemical test in 3.5% NaCl solution (a)

wt% SiC (B1), (b) AlMgSi/5 wt% RHA5 wt% SiC) AlMgSi/7.5 wt% RHA.

containing 7.5 wt% RHASiC reinforcement, it isat the hybrid composites C2, C3, and C4 (whichA and SiC in weight ratios 1:3, 1:1 and 3:1, respec-

comparable coefcient of friction with the singleAlMgSi/SiC composite (C1). For the 10 wt% rein-

it is observed that D4 (hybrid composite containing

COF

0

0.5

0.4

0.3

0.2

0.1

0

-0.1

-0.2

COF

0.5

0.4

0.3

0.2

0.1

0

-0.1

-0.2

0

0

b

c

Fig. 5 VarAlMgSi breinforcem10 wt% RHA

RHA and SAlMgSi/Rhigher RHAparison wiand the sinthat the adAlMgSi b

The weamicrographthe secondcomposite topographiwhich occasamples. Tthat showedue to the l(Fig. 6c andthese compcoefcients200 400 600

Time (s)A0 B1 B2 B3 B4 B5

800 1000

200 400 600

Time (s) 800 1000A0 C1 C2 C3 C4 C5

A0 D1 D2 D3 D4 D5

200 400 600

Time (s) 800 1000

iation of coefcient of friction with time for theased composites containing (a) 5 wt% RHASiCent, (b) 7.5 wt% RHASiC reinforcements, and (c)SiC reinforcement.

iC in weight ratio of 3:1) and D5 (single reinforcedHA composite) which are both characterized by

content have lower coefcient of friction in com-th the other hybrid composite grades (D2 and D3)gle reinforced grade D1. This is an added indicationdition of RHA can improve the wear resistance ofased composites.r results reported in Fig. 5 are supported by the SEMs mechanisms proposed above and conrmed byary electron images of the worn surfaces of all thegrades. These images show similar wear surfacees characterized mostly by abrasive wear featuressional worn debris welded to the surface of thehe samples C5 and A0 were the few exceptionsd a more predominant adhesive wear mechanismarge accumulation of debris visible on the surfaces

d). Adhesion of worn out debris to the surface ofosites is largely responsible for the higher friction

observed [25,26].

j m a t e r r e s t e c h n o l . 2 0 1 4;3(1):916 15

A

B

C

Fig. 6 Somworn surfaAlMgSi/7RHA3.75 w

4. Co

The corrosi

The effebehaviou

consistent for the different weight percent of reinforcement(5, 7.5, and 10 wt%) used in developing the AlMgSi based

posias evementancerentrix acom It w

forcresis

Prefmate representative SEM photomicrograph of theces of the composites produced (a).5 wt% SiC (C1), AlMgSi/1.25 wt%t% SiC (B2), and (c) AlMgSi/7.5 wt% RHA (C5).

nclusions

on and wear results show that:

ct of RHA/SiC weight ratio on the corrosionr of the composites in 3.5% NaCl solution was not

faces wa The coe

resistancthat of SiC.

The prodcomposiforcemencorrosionthe corrohybrid co

Conicts

The author

r e f e r e n

[1] Prasad propert2011;33

[2] ZuhailaFabricareinforc4755.

[3] SenthilKeerthiAl2O3 amatrix 2012;62

[4] Hao S, XmechancomposMater R

[5] Sajjadi mechancompos2011;52

[6] Kaveen(Al3Zr +reinforcpressin

[7] Rohatgstretch2007;2:1

[8] TahamtAl/A206milling2013;49

[9] NareshcomposresistanEnginee2006. p.tes.ident that for most cases the use of hybrid rein-t of RHA and SiC resulted in improved corrosione of the composites in 3.5% NaCl solution.ial dissolution of the more anodic AlMgSi alloyround the AlMgSi matrix/RHA/SiC particle inter-s identied as the primary corrosion mechanism.fcient of friction and consequently the weare of the hybrid composites were comparable tothe AlMgSi alloy matrix reinforced with only

uction of low cost AlMgSi alloy matrix hybridtes using rice husk ash as a complementing rein-t to silicon carbide has great promise for high

and wear resistance applications judging fromsion and wear properties exhibited by most of themposites.

of Interest

s declare no conicts of interest.

c e s

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velan T, Gopalakannan S, Vishnuvarthan S,varan K. Fabrication and characterization of SiC,nd B4C reinforced AlZnMgCu alloy (AA 7075) metalcomposites: a study. Adv Mater Res2623:12959.ie J. Tensile properties and strengtheningisms of SiCp-reinforced aluminum matrixites as a function of relative particle size ratio. Jes 2013;28:204755.SA, Ezatpour HR, Beygi H. Microstructure andical properties of AlAl2O3 micro and nanoites fabricated by stir casting. Mater Sci Eng A8:876571.dran B, Wang GS, Huang LJ, Geng L, Peng HX. In situ

Al2O3np)/2024Al metal matrix composite with novelement distributions fabricated by reaction hotg. J Alloys Compd 2013;581:1622.i P, Schultz B. Light weight metal matrix composites ing the boundaries of metals. Mater Matters69.an S, Halvaee A, Emamy M, Zabihi MS. Fabrication of-Al2O3 nano/micro composite by combining ball

and stir casting technology. Mater Des:34759.

P. Development and characterization of metal matrixite using red Mud an industrial waste for weart applications. India: Department of Mechanicalring, National Institute of Technology Rourkela;

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Corrosion and wear behaviour of AlMgSi alloy matrix hybrid composites reinforced with rice husk ash and silicon carbide1 Introduction2 Materials and methods2.1 Materials2.2 Composites production2.3 Corrosion test2.4 Wear test2.5 Scanning electron microscopy (SEM)

3 Results and discussion3.1 Electrochemical behaviour3.2 Wear behaviour

4 ConclusionsConflicts of InterestReferences