Characterization of Coconut Shell Ash for

P.B Madakson et al. / International Journal of Engineering Science and Technology (IJEST)

Characterization of Coconut Shell Ash for Potential Utilization in Metal Matrix Composites for Automotive Applications. P.B Madakson, D.S.Yawas and A. Apasi. Department of Mechanical Engineering, Ahmadu Bello University, Samaru, Zaria, Nigeria Abstract Coconut shell ash is agricultural waste. The waste is produced in abundance globally and poses risk to health as well as environment. Thus their effective, conducive and eco-friendly utilization has always been a challenge for scientific applications. This paper mainly deals with identification of characteristics of coconut shell ash using spectroscopic and microscopic analysis. Density, Particle size, Refractoriness, SEM, XRD, XRF and FTIR spectroscopic methods were used for the characterization of the coconut shell ash. The results were compared and it was observed that the ash possesses nearly same chemical phases and other functional groups as reinforcement like fly ash, rice husk ash, bagasse ash that have been in Metal Matrix Composites (MMCs) specifically for automobile applications. Hence, coconut shell ash can be used as a low cost reinforcement in Metal Matrix Composites (MMCs). Key Words: Density; microstructure; particle size; refractoriness

1.

Introduction

Researches all over the world today are focusing on ways of utilizing, either industrial or agricultural wastes as a source of raw materials for the industry. These wastes utilization would not only be economical, but may also result to foreign exchange earning and environmental pollution control[1-2] Metal matrix composites (MMCs) posses significantly improved properties including high specific strength specific modulus, damping capacity and good wear resistance compared to unreinforced alloys[2-4]. Similarly, there has been an increasing interest in composites containing low density and low cost reinforcements. Among various discontinuous dispersoids used are fly ash, red mud, Rice husk ash[1-5] are

some of the most

inexpensive and low density reinforcement available in large quantities as solid waste by- product. Coconut shell is an agricultural waste and is available in very large quantities throughout the tropical countries of the world. Moreover, coconut is becoming an important agricultural product for tropical countries around the world as a new source of energy-biofuel[6]. Previously, coconut shell was burnt as a means of solid waste disposal which contributed significantly to CO2 and methane emissions [6]. However as the cost of fuel oil, natural gas and electricity supply has increased and become erratic, coconut shell has come to be regarded as source of fuel rather than refuse. Presently, the Nigeria coconut shell is used as a source of fuel for the boilers, and residual coconut shell is disposed off as gravel for plantation roads maintenance. Black smiths also buy the coconut shell as fuel material in their casting and forging operations[6].

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Bamgboye and Jekayinfa[6] regretted that 90% of coconut (empty fruit bunches, fibers, fronds, trunks, shell) was discarded as waste and either burned in the open air or left to settle in waste ponds. This way the coconut processing industries waste according to him contributed significantly to CO2 and methane emissions. Based on economic as well as environmental related issues, efforts should be directed world wide towards coconut management issues i.e. of utilization, storage and disposal.

Different avenues of coconut shell

utilization are more or less known but none of them have so far proved to be economically viable or commercially feasible. Hence, the objective of this present work is to characterize coconut shell in order to explore its use in metal matrix composites. 2.

Materials and Method

2.1

Material The coconut shell used in this work was obtained from a coconut seller in Kaduna, Kaduna state of

Nigeria. The photograph of the coconut shell is shown in Plate 1.

(a) Coconut shell

(b) Crushed coconut shell Plate 1: Photograph of the Coconut shell.

2.2

Equipment Equipment used in this research are- electrical resistance furnace, X-ray diffractometer (XRD),

Scanning electron microscope with energy dispersive spectrometer (SEM/EDS) Machine, X-ray fluorescent XRF 2.3

Methods

2.3.1

The processing of the coconut shell (Carbonization) The coconut shell was grinded to form coconut shell powder, the powder was packed in a graphite

crucible and fired in electric resistance furnace at temperature of 1300oC to form coconut shell ash (CSAp)(see Plate 2 ).

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(a) Coconut shell powder

(b) Coconut shell ash

Plate 2: Photograph of coconut shell ash

2.3.2

Particles size analysis The particle size analysis of the coconut shell ash particles was carried out in accordance with

BS1377:1990[7].

About 100g of the coconut shell ash particles was placed unto a set of sieves arranged in

descending order of fineness and shaken for 15minutes which is the recommended time to achieve complete classification. The weight retained on each sieve was taken and expressed as percentages of the total sample weight. From the weight retained, the grain fineness number (AFS) was computed [8]. 2.3.3 Density Measurement Density measurements were carried out on the coconut ash sample using Archimedes’s principle. The buoyant force on a submerged object is equal to the weight of the fluid displaced. This principle is useful for determining the volume and therefore the density of an irregularly shaped object by measuring its mass in air and its effective mass when submerged in water (density = 1 gram/cc). This effective mass under water was its actual mass minus the mass of the fluid displaced. The difference between the real and effective mass therefore gives the mass of water displaced and allows the calculation of the volume of the irregularly shaped object. The mass divided by the volume thus determined gives a measure of the average density of the sample [8]. 2.3.4 Refractoriness The Pyrometric Cone Equivalent (PCE) as recommended by ASTM Test C-24 was used in the determination of the refractoriness of the sample [2]. 2.3.5 Mineralogical Characterization of the Coconut Shell ash Mini Pal compact energy dispersive X-ray spectrometer (XRF) was used for the elemental analysis of the coconut shell ash. The system is controlled by a PC running the dedicated Mini Pal analytical software [8]. The XRD analysis of the coconut shell ash was carried out using Philips X-ray diffractometer. The o X-ray diffractograms was taken using Cu Kα radiation at scan speed of 3 / min. The samples were rotated at

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precisely one-half of the angular speed of the receiving slit, so that a constant angle between the incident and reflected beams is maintained. The receiving slit is mounted in front of the counter on the counter tube arm, and behind it is usually fixed a scatter slit to ensure that the counter receives radiation only from the portion of the specimen illuminated by the primary beam. The intensity diffracted at the various angles was recorded automatically on a chart and the appropriate (Ө) and (d) values were then obtained[7-9].

2.3.6

Micro structural Analysis

The microstructure and the chemical compositions of the phases present in the coconut shell ash was TM studied using a JOEL JSM 5900LV Scanning Electron Microscope equipped with an Oxford INCA Energy Dispersive Spectroscopy system. The s a m p l e was placed on sample holder and the images were captured under various magnifications. Prior to it, sample was applied with the gold coating to avoid charge effect, so to obtain clear images. The SEM was operated at an accelerating voltage of 5 to 20 kV[2].

2.3.7

Fourier Transform Infrared Spectroscopy (FTIR)

FTIR-8400S Fourier transform infrared spectrophotometer (SHIMADZU ) was used for the functional groups present in the coconut shell ash. Spectrometer and detector, capable of measuring functional group to the predetermined minimum detectable level. The system include a personal computer with compatible software that provides real-time updates of the spectral profile during sample collection and spectral collection using FTIR system using 1 cm-1 resolution, 22 meter path length, and a broad band MCT detector. The Data analysis was performed using appropriate reference spectra whose concentrations can be verified using CTS spectra[7].

3.0 Result And Discussion From the particle size analysis results, it is shown that, the coconut shell ash has a Grain Fineness Number (GFN) of 75.08. The sample can be considered to be fine as GFN value of 100 is ranked the finest. Also, the sample can be considered to have met the AFS specification since four sieve-size, has the bulk of the retained sample on four consecutive sieves corresponding to 355μm, 180μm, 125μm, and 63μm size fractions respectively [2]. The density of the coconut shell ash is 2.05g/cm3 which means that coconut shell ash is very light material. The value obtained fall within the range of density of fly ash, bagasse and silica which is 1.8 and 2.2 g/cm3 respectively [1, 2] currently used in metal matrix composites

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The coconut shell ash was observed to have Seger Cone No. 22, with equivalent temperature of 1500oC. This means coconut shell ash can withstand operating temperature of 1500oC without load [1-4].

The XRD pattern(see Figure 1) obtained reveal that, the major diffraction peaks are 20.75°, 10.22° and 35.40o and their inter-planar distance, 3.87Å, 8.66 Å and 2.54Å, and their

relative intensity of X-ray

scattering are 100.00, 61.90 and 8.44 and phases at these peaks as Quartz(SiO2), Cordierite, syn (Mg2 Al4Si5O18) and

Moissanite(SiC), while each of these phases have a score of 44, 32 and 16

respectively(see Table 1).

Si O2; Si C

5 00

Si O2; Si C

Si O2; Si O2

Si C

10 00

Mg2 Al4 Si5 O18

Mg2 Al4 Si5 O18

d2_ 00940 -ver3 .raw

Si O2; Mg2 Al4 Si5 O18; Si O2

Mg2 Al4 Si5 O18

Si O2; Mg2 Al4 Si5 O18; Si O2

C ounts

0 20

30

40

50

60

70

80

90

P ositio n [°2 Theta]

Figure 1: XRD pattern of Coconut shell ash

Table 1: Identified patterns list of coconut shell ash Visible

Ref. Code

Score

Compound Name

Displacement

Scale Factor

Chemical Formula

[°2Th.] *

00-043-0596

44

Silicon Oxide

0.000

0.912

Si O2

*

00-013-0294

32

Cordierite, syn

0.000

0.590

Mg2 Al4 Si5 O18

*

01-089-1961

26

Quartz low,

0.000

0.642

Si O2

0.000

0.207

Si C

dauphinee-twinned *

01-075-1541

16

Moissanite 6\ITH\RG

The results showed that SiO2 has the highest percentage of all the compound and element present as revealed by the XRD analysis. Complete Mineralogical analysis carried out by X-ray diﬀraction also

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revealed that the ash contains each of these elements C, O, Mg, Al, Si" Fe, Na, K, Zn and none of these elements H, He, Li, Be, B, N, F, Ne, P, S, Cl, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, which means that with the absence of all these other elements the coconut shell ash may not contain radioactive materials. This is in par with the earlier of other biomass by[1-2]. The XRD result showed that both SiO2 and SiC have a fine structure, the former having a finer one. This could b e associated with pore size [2]. The XRF chemical composition of the coconut shell ash is represented in Table 2.

X RF ana lysis

confirmed that SiO2, Al2O3, MgO and Fe2O3 were found to be major constituents of the ash. Silicon dioxide, iron oxide and alumina are known to be among the hardest substances. Some other oxides viz. CaO, K2O, Na2O and MnO were also found to be present in traces. The presence of hard elements like SiO2, Al2O3 a n d Fe2O3 suggested that, the coconut shell ash can be use as particulate reinforcement in various metal matrixes. This result of XRF is in agreement with the result of XRD obtained. Therefore, the present work suggests the possibility of using coconut shell ash as particulate in metal matrix composites since the chemical composition has close similarity with the XRF analysis of rick husk ash, bagasse ash and fly ash currently used in metal matrix composites[1-4]. Table 2: XRF analysis of Coconut shell ash

Element

Al2O3

CaO

Fe2O3

K2O

MgO

Na2O

SiO2

MnO

ZnO

%

15.6

0.57

12.4

0.52

16.2

0.45

45.05

0.22

0.3

Particle Morphology of coconut shell ash can be seen in back scattered electron (BSE) as shown in Figure 2. Coconut shell ash particles were observed to be solid in nature, but irregular in size. Some spherical shape particles can also be seen in the Figure 2. The chemical analysis of the coconut shell ash morphology consists mainly of Si, C, O, Mg, Al with small amounts of Fe as shown in the EDS scan (see Figure 2). The results are consistent with XRD and XRF analysis of other biomass by[1-5].

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Figure 2: SEM/EDS spectrum of Coconut shell ash

Mainly twenty peaks were detected in the FTIR Analysis of the coconut shell ash as visible in Figure 3. These peaks are shown in Table 3. This result has shown that the presence of quartz in the original ash gives rise in the IR spectrum to a series of bands located at 1132 and 443.64 cm-1. The presence of mullite, in turn, is responsible for a series of bands at around 3797 cm-1. The presence of carbon group is present in series of bands at around 4091.15-4617.74 cm-1. Quartz, mullite and the vitreous phase of the ash overlap in the area between 1220 cm-1 and 1434.12cm-1. Hence Quartz, Mullite, carbon and vitreous phases are confirmed to be present. More over the peaks in treated and untreated cases does not show any variations. This is in agreement with the earlier work of [4, 9].

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Figure 3: FTIR spectrum of Coconut shell ash

Table 3: Identification Peaks of the FTIR analysis

4. Conclusions

From the analysis of the results and discussion given above, the following conclusions can be made.

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1)

XRD analysis of the coconut shell ash reveals Silicon Oxide: (SiO2), Corderite,syn:(Mg2 AlSi5O18),Quartz:(SiO2) and Moissanite (SiC) as the primary compound with SiO2 as the highest percentage of all the compound and element present.

2)

XRF studies revealed the presence of hard element like SiO2, Al2O3, MgO and Fe2O3 as major constituents which can be used as particulate reinforcements in MMCs for automobile applications.

3)

FTIR graphs showed that Quartz, Mullite and Vitereous, carbon phases were present in coconut shell ash powder and proposed to use coconut shell ash as particulate reinforcement in MMCs.

4)

The coconut shell ash can withstand a temperature of up to 1500oC with a density of 2.05g/cm3. That means this ash can be use in production light weight MMCs component with good thermal resistance.

5.0 REFERENCES [1] [2] [3] [4] [5]

[6] [7]

[8] [9]

Bienia J, Walczak .M, Surowska, B, Sobczaka J (2003): Microstructure and corrosion behaviour of aluminum fly ash composites, Journal of Optoelectronics and Advanced Materials, 5, No. 2,493 – 502. Aigbodion .V. S., Hassan S. B., Ause .T. and Nyior,.G.B(2010):. Potential Utilization of Solid Waste (Bagasse Ash), Journal of Minerals & Materials Characterization & Engineering, Vol. 9, No.1, pp.67-77, Siva Prasad. D and Rama Krishna. A(2011): Production and Mechanical Properties of A356.2 /RHA Composites, International Journal of Advanced Science and Technology Vol. 33, 51-58 Arun Kumar M. B and Swamy R. P(2011): Evaluation of Mechanical Properties of Al6061, Flyash And E-Glass Fiber Reinforced Hybrid Metal Matrix Composites, ARPN Journal of Engineering and Applied Sciences, VOL. 6, NO. 5,40-44. Naresh P(2006): Development and characterization of metal matrix composite using red Mud an industrial waste for wear resistant applications, PHD thesis Department of Mechanical Engineering, National Institute of Technology Rourkela -769 008 (India), January, pp23-34. Bamgboye A. Isaac and Jekayinfa .S. O(2006): Energy Consumption Pattern in Coconut Processing Operations. Agricultural Engineering International: the CIGR Journal Manuscript EE 05 013. Vol. VIII. Rajan T.P.D, Pillai R.M, Pai B.C., Satyanarayana K.G, Rohatgi, P.K (2007): Fabrication and characterization of Al–7Si– 0.35Mg/fly ash metal matrix composites processed by diﬀerent stir casting routes, Composites Science and Technology, 67, 3369–3377. Aigbodion. V.S(2010): Potential of using bagasses ash particle in Metal Matrix Composite, PHD Department of Metallurgical and Materials Engineering, Ahmadu Bello University, Samaru, Zaria, Nigeria Ejilofor J. U and Reddy R.G(1997): Developments in the processing and properties of particulate Al-Si Composites, Jom publication of minerals metals and materials society 49 (11), pp 31-37.

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Characterization of Coconut Shell Ash for

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