International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue5- May 2013
Tribological Properties Of Epoxy/Al2o3
Nanocomposites
Sudheer Kumar.N 1, Venkateswara Rao.K2*, Chakraverti.G1, Shilpa Chakra.CH2
1
Department of Mechanical Engineering Mahaveer Institute of Science and Technology, Hyderabad
2
Center for Nano Science and Technology, IST, JNTU Hyderabad
Andhra Pradesh, India
Abstract— Tribology is the science and technology of friction,
wear and lubrication of interacting surfaces in relative motion.
The sliding wear performance of Epoxy composites filled with
nano-sized Al2O3 particles was studied in this paper. For this
study, Al2O3 nanoparticles were synthesized by solution
combustion process and size was found to be 28nm from X-ray
Diffraction (XRD) and Morphology of Al2O3 nanoparticles by
Scanning Electron Microscopy (SEM). Epoxy/ Al2O3 nano
composite were synthesized by Al2O3 nanoparticles and resin
with different hardeners like K-6, K-47 with appropriate
amounts like 1 wt% of Al2O3 nanoparticles. The wear
performances were studied by using pin-on-disc wear testing
machine.
Keywords— Epoxy/Al2O3nanocomposites, XRD, SEM, and Pinon-Disc set up
I. INTRODUCTION
In any high-tech structural application, strength, stiffness,
durability and light weight are required, epoxy resins are seen
as the minimum standard of performance for the matrix of the
composite. This is why in aircraft and aerospace applications,
as well as offshore racing boats, epoxies have been the norm
for years [1]. Epoxy resins have been widely used in many
industrial applications such as construction materials,
composite adhesives, laminates, and coatings owing to their
excellent mechanical properties, low cost, ease of processing,
fine adhesion to many substrates, and good chemical
resistance [2].
Over the last 10 years, epoxy nanocomposites have
been attracted considerable attention from both fundamental
research and application point of view. Resin B-47 (3221) is a
modified liquid resin of low viscosity used in this study. It can
be suitably formulated into high strength adhesives, solvent
free coatings and floor toppings. These formulations are
generally used as room temperature curing systems and it
appearance clear pale yellow liquid. Epoxy Hardeners like K6, K-46 (5107) are added to the resin at a ratio of
100:10,100:50 and these acts as curing agent.
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The most common material used as a matrix in
nanocomposites are polymers (e.g. epoxy, nylon, polyepoxide,
polyetherimide, etc.,), ceramics (e.g. alumina, glass, porcelain,
etc.,), and metals (e.g. iron, titanium, magnesium, etc.,).
Polymers and their composites form a very important class of
tribo-engineering materials and were invariably used in
mechanical components such as gears, cams, bearings, bushes,
bearing cages, etc. where wear performance in non-lubricated
condition was a key parameter for the material selection [3].
II. EXPERIMENTAL DETAILS
A. Materials
The material used in this study to produce epoxy
resin specimens were resin B-47 (3221) and the hardeners K-6
and K-46 (5107) from Allied Agencies. The epoxy resin
system is widely used in practice and has an advantage of low
viscosity at room temperature. For this study, aluminium
oxide is prepared by solution combustion process (diameter 28
nm).
B. Synthesis of Al2O3 nanoparticles
Aluminium oxide is prepared by solution combustion
process. Stoicheiometric amount of aluminium nitrate and
urea are taken into beaker and stirred it for 30 minutes on a
magnetic stirrer and placed it on a hot plate (~1000°C).
Heating rapidly the solution contains redox mixture boils,
frothing and smouldering, flaming, fumes and catches fire and
burns with an in candescent flame to yield Al2O3 with
evolution of large amount of gases like carbon dioxide,
hydrogen oxide in the form of flames. This procedure was
done in open air instead of doing it in closed vessel.
C. Synthesis of Epoxy/Al2O3 Nanocomposites:
Synthesis of Epoxy/Al2O3 nanocomposites are
prepared by mixing resin type B-47(3221) with different
Epoxy hardeners (K-6, K-46(5107)) of ratio 100:10, 100:50
for 1 wt% of Al2O3nanoparticles. For preparing nanoAl2O3/Epoxy composites, both the resin and filler with desired
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proportion were carefully mixed under magnetic stirrer for 30
min and ultra-sonication for another 30 min and then pour in a
prepared wooden mould of 60x6mm length and diameter and
cure it for one day, it taken out from the mould and post cure
it for another one day, then the wear specimens are cut as per
the dimensions. The above fabrication process is carried for 1
wt% of treated Al2O3 nanoparticles. The treated Al2O3
nanoparticles are reinforced with 1 wt% of Al2O3
nanoparticles to study the influence of Al2O3 nanoparticles.
Fig.1(a): Sample (k-6)
Fig.1(b): Sample (k-47)
The above figure 1(a) and 1(b) shows synthesized
Epoxy/Al2O3 nanocomposites with different hardeners like K6, K-47. It is very hard to remove the samples from the
wooden mould.
D. Wear Experimental Procedure
Wear Experiments have been conducted in the Pinon-disc type friction and wear monitor (DUCOM; TL-20)
with data acquisition system, (Figures 2(a) and 2(b)) which is
used to evaluate the wear behaviour of the composite, against
hardened ground steel disc (En-32) having hardness of 65
HRC and surface roughness (Ra) of 0.5µm. It is versatile
equipment designed to study wear under sliding condition
only. Sliding generally occurs between a stationary pin and a
rotating disc.
Fig.2(a): Pin on disc set up
The disc rotates with the help of a D.C. motor having
speed range 0-2000 rev/min with wear track diameter 50 mm180 mm, which could yield sliding speed 0 to 10 m/sec. Load
is to be applied on pin (specimen) by dead weight through
pulley string arrangement. The system has a maximum
loading capacity of 200N.
Dry sliding tests were conducted at ambient
conditions of temperature and humidity with different normal
loads (5N, 10N) and sliding velocity 640 RPM. Prior to each
test, the composite specimens was rubbed over a Sic abrasive
paper upto 166-grade to ensure proper intimate contact
between the sliding face of the specimen and stainless steel
counter face. Also before each test, the wear track on the disc
was refreshed by pressing on abrasive paper (silicon carbide
water proof, grade 800) for few minutes to ensure same initial
condition.
E. Characterization Techniques
Al2O3 nanoparticles were characterised by X-Ray
Diffraction (XRD) to find the average crystalline size.
Scanning Electron Microscopy (SEM) is used to find the
morphology of Aluminium Oxide. Pin-on–Disc wear testing
machine is used to find the friction force, coefficient of
friction and wear properties of Epoxy/Al2O3 nanocomposites.
III RESULT AND DISCUSSION
A. X-Ray Diffraction of Al2O3:
In the XRD pattern of the Al2O3 nanoparticles, the
peaks are observed at 25.560, 35.140, 37.770, 43.340, 52.560,
57.480 and 68.180 the (h k l) values of the peaks are (0 1 2),
(1 0 4), (1 1 0), (1 1 3), (0 2 4), (1 1 6) and (3 0 0) respectively.
These results are coincided with JCPDS card number 77-2135,
and it shows that the Al2O3 nanoparticles having the
rhombohedra structure. The average crystalline size is
measured by using Debye-Scherer’s formula [4].
Fig.2(b): Pin on disc
Fig.3: XRD Pattern of Al2O3 Nanoparticle
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International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue5- May 2013
According to the Debye-Scherer’s equation:
approximately in both the cases and the wear rate increases
gradually in K-6 hardener compared to K-46 hardener as
shown in the graph below.
Where D – Average size of the particle (nm)
--Wavelength of the radiation (A°)
θ –Diffraction angle (degree)
B – Full width half maximum (FWHM) of the peak
(radians)
From the above formula we obtained the average crystalline
size is 28nm. The lattice parameter a = b = 4.760 A°, c =
12.994 A°.
B. Scanning Electron Microscopy of Al2O3:
Scanning Electron graphs were taken with a
HITACHI S3400NS SEM operated at 15KV. It shows
different surface properties at different magnification as
shown in the figure below. The Al2O3 nanoparticles are
formed like sheet structure because the combustion of Al2O3
nano particles was done in open air, instead of doing in closed
vessel. This is the reason why it appears sheet like structure.
Fig. 5(a): Wear loss of k-6 hardener
Fig. 5(b): Wear loss of k-46 hardener
Finally we conclude from the figure 6 that the mass
loss of K-6 hardener is better compare to K-46 hardener in
both the cases. Especially the mass loss of K-46 hardener at
7.5KN is twice that of the K-6 Hardener as shown in the
figure below 6.
Fig. 6: Wear volume of composites as a function of loads
IV. CONCLUSIONS
Fig. 4 : SEM images of Al2O3 Nanoparticle
C. Wear Performance:
In general, the friction and wear properties always
describe the whole tribological system rather than a material
property alone [5]. Sliding speed of the disc is 0.52 m/sec and
also calculated the sliding distance from the data is 942.6
meters. Initially the test was conducted at 2KN with 250rpm
on En-31 Steel Disc of hardens 65 Rc, track diameter of 40mm
and surface roughness of 0.4µm it shows no mass loss in the
composites.
The second test was conducted at 5KN with same
parameters, then ultra- soincate the sample for 5 minutes. The
weight is measured to know the mass loss of the composites.
The frictional force and coefficient of friction remain constant
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Filling of nano Al2O3 particles in epoxy changed the
microstructure of epoxy and prevented the destruction of
epoxy banded structure during the friction process which
might be one of the anti-wear mechanisms of nano Al2O3. The
improvement and the best tribo-performance of the
epoxy/1wt% of Al2O3 nanocomposites attributed to the
agglomerations of nano Al2O3 particles in epoxy composite
have been avoided. Epoxy Hardener K-6 shows better Wear
performance compared to K-46 hardener at different loading
conditions. The mass loss of the hardener K-46 is twice that of
K-6 hardener at 7.5KN. XRD pattern reveals that the Al2O3
Nanoparticles contains the Rhombohedra Structure and
average crystalline size measured to be 28nm.Morphology of
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International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue5- May 2013
Al2O3 nanoparticles shows sheet like structure because of the
combustion was done in open air.
REFERENCES
[1] Gurit, the Advantages of Epoxy Resin versus Polyester in
Marine Composite Structure.
[2]
WalidNaous,
Xiao-Yanyu,
Qing-Xin
Zhang,
Kimiyoshinaito, Yutakakagawa, Journal of polymer science:
Part B: Polymer Physics, 44 1466-14732006.
[3] Hutchings I.M., Tribology, Friction and Wear of
Engineering Materials.CRC press, London 1992.
[4] Vineet Singh, Pratima Chauhan Chalcogenide Letters 6
421 2009
[5] Naga Raju B., Ramji K.and Prasad V. S. R. K.,ARPN
Journal of Engineering and Applied science vol. 6, no. 6, June
2011.
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