The fabrication and characterisation of pure aluminium Composite/alumina particle via powder metallurgy
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Date
2009
Authors
Ahmad, Khairel Rafezi
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Abstract
This study describes the effect of particles sizes (0.5 μm, 1.0 μm, 3.0 μm, 12.0 μm and
25 μm) and weight percentage (5 wt. %, 10 wt. %, 15 wt. %, 20 wt. %) of alumina
particles reinforcement materials on the properties of pure Al metal matrix composites
(MMC) reinforced with alumina particles including the physical, mechanical, thermal
properties and corrosion resistance via powder metallurgy method. This research was
done due to the factor that Al alloy have needs to improve the low corrosion resistance
of Al alloy compared to pure Al. The composite was produced via powder metallurgy
method. The composites powder were milled for 4 hours with addition of 15 wt.% of
milling media. Composite mixture was compacted at pressure 250 MPa. Sintering was
done at 600°C for 5 hours in inert argon gas environment. Microstructure analysis,
shrinkage/expansion, density, porosity, hardness, vibration sonic modulus, three point
bend test, thermal expansion and corrosion resistant were carried out on the sintered
composites. The addition of Al2O3 particles into the Al matrix enhanced the corrosion
resistance and also increased the physical, mechanical and thermal properties of Al
matrix. Density and porosity of the composites are in range of 2.71 – 2.88 g/cm-3 and
4.17 -8.10 %, respectively. A composite reinforced with 0.5 μm Al2O3 particle shows the
highest hardness value which is 70.1 HVN and lowest coefficient of thermal expansion
which is 15.2 x 10-6 m.K-1. The pure Al MMC reinforced by particles shows better wear
and corrosion resistance compared to the matrix without reinforcement. The small
particles act as barrier to prevent movement of dislocation and sliding of matrix plane.
Composite reinforced by smaller particles contains highest amount of barrier per unit
area compared to coarser particle sizes at the same volume and weight percentage.
Increasing the weight percentage of reinforcement particles contributed to the
increasing amount of barrier which is Al2O3 which prevent the movement of dislocation
which contributed to the increasing hardness value. In overall, this research found that
the increase in particle sizes of reinforcement resulted in increasing of shrinkage,
density, elastic modulus and wear resistance of the composites. Meanwhile,
percentages of porosity, modulus of rupture, coefficient of thermal expansion increase
as the particle sizes increase. The increasing of weight percentage of reinforcement
has increased the density, hardness value, elastic modulus and wear resistance.
Meanwhile percentage of porosity, shrinkage percentage, modulus of rupture and
thermal expansion coefficient of the composites decrease with the increases of weight
percentage of Al2O3 reinforcement particle.
Description
PhD
Keywords
Science Physic , Fabrication , Pure aluminium , Powder metallurgy