Aligned carbon nanotube reinforced high performance polymer composites with low erosive wear
Introduction
Solid particle erosion is a dynamic process which involves the progressive loss of materials from a surface by means of impinging particles from various directions. This type of wear has been paid much attention as it causes severe problems including loss of efficiency, reduced performance and high maintenance costs in many industrial applications. For example, helicopter rotor blades and high-speed vehicles, whose surfaces are usually exposed to air which contains sharp and solid particles. Extreme conditions like sandy or dusty environments may even speed up the erosive wear process resulting in more damage.
Since the early 1980s, research studies on the solid particle erosive wear behaviour of materials have extended from metallic materials to fibre reinforced polymer composites [1], [2], [3]. Fibre reinforced polymer composites provide extra benefits including lightweight, excellent specific stiffness and strength, freedom in design due to tailorable anisotropy [4], and these advantages contribute to various applications from daily-use appliances to high-tech engineering and aircraft systems. However, the erosive wear resistance has remained a major issue because polymer composites usually exhibit relatively poor resistance to erosion compared to metallic materials [3] and, in some cases, the presence of fibres reduces the erosion resistance of the polymer matrix [5], [6]. Efforts have been made to design composite laminates reinforced with multi-directional fibres which help to absorb additional impact energy from solid particles, but the improvements in erosion resistance were found to be very limited in the case of both carbon fibres [7] and glass fibres [5].
Since the discovery of carbon nanotubes (CNTs) [8], their extraordinary multifunctional properties have stimulated great interest in polymer composites reinforced with CNTs. Particularly, due to their graphitic structure, CNTs exhibit lubricating behaviour [9], [10], [11], [12] which is reported to make significant improvements to the abrasive wear resistance of CNT based nanocomposites [13], [14]. However, the erosive wear resistance of CNT based polymer composites has received much less attention due to the developing stage of CNT synthesis as well as the manufacturing difficulties in production of bulk polymer composites containing a high loading fraction of CNTs. The erosive wear performance of epoxy composites reinforced with aligned CNT arrays synthesized by substrate-grown CVD method has only recently been reported [15]. In this paper, the presence of vertically aligned CNT arrays within epoxy matrix gives improved erosion resistance which opens up a new way for erosive wear applications of polymer composites using aligned CNTs. Inspired by this work, CNTs films synthesized by the continuous CVD process [16] can be assembled together to fabricate uni- or multi-directional CNT film/epoxy based composites. Such CNT structures can then be mechanically comparable to conventional fibre reinforced polymer composites. To date, the incorporation of multi-layered CNT films in an epoxy matrix has produced composites with significantly improved fracture toughness and Young’s modulus [17].
In the present work we investigate the erosive wear behaviour of epoxy based composites reinforced with as-produced, uncondensed CNT films. The CNT film epoxy composites were prepared in two different nanotube alignment configurations, where CNT films within the epoxy matrix were stacked either unidirectionally (0°) or bidirectionally (0°/90°) in order to investigate the effect of CNT film orientations on the erosive wear behaviour of epoxy based composites. In addition, unidirectional (0°) carbon fibre/epoxy composites were also fabricated for comparison.
CNTs used in this work were synthesised using the direct-spinning CVD method, from which continuously long CNTs were collected onto the rotational drawer, forming CNT films. A vacuum bagging system was set up to fabricate both unidirectional (0°) and bi-directional (0°/90°) CNT film/epoxy composites.
This work demonstrates methods to investigate the erosive wear resistance of epoxy composites reinforced with a high loading fraction of aligned CNT films. Results have shown that the two types of CNT film reinforced epoxy composites exhibit superior erosive wear resistance compared to unidirectional (0°) carbon fibre reinforced epoxy composites. In particular, the bidirectional CNT films within the epoxy matrix will absorb additional impact energy from solid particles, resulting in improved erosion resistance. The erosive wear mechanisms of composites were further investigated at various impingement angles using SEM analysis. In addition, the aligned CNT film reinforced epoxy composites with high electrical conductivity also provide an exciting opportunity for multifunctional purposes such as lightweight lighting strike protection [18].
Section snippets
CNT synthesis and characterisation
Carbon nanotubes used in the study were synthesised via continuous CVD process [16]. Methane was used as the hydrocarbon feedstock and was injected into the hot furnace (1300 °C) along with ferrocene and thiophene. CNTs start to grow in the furnace and form an aerogel, which can be mechanically drawn out of the furnace. In this way, CNT films were produced by continuously collecting CNTs onto the rotational winder until the winder was fully covered. Typical collection time is about 1 h. The
Erosion performance
A series of erosion tests were carried out to assess the effect of two alignment configurations of CNT films in the epoxy matrix on the erosive wear behaviours. The results were compared to unidirectional (0°) carbon fibre epoxy composite and neat epoxy (Fig. 5a and b).
Fig. 5a shows the erosion rates as a function of impingement angles. Ductile and brittle erosion behaviour can be clearly differentiated from this diagram. The maximum erosion rate of unidirectional (0°) carbon fibre/epoxy
Conclusions
The effect of CNT film reinforced structures on erosive wear performance of epoxy composites has been investigated. The aligned, as-produced CNT films were stacked in two alignment configurations: unidirectional (0°) and bidirectional (0°/90°). The experimental results show that the two types of CNT film reinforced epoxy composites have the same ductile erosive wear behaviour as neat epoxy where their erosion rates peak at the impingement angle of 30–45°. Their erosion resistance is superior to
Acknowledgements
K.K.K. Koziol and J. Chen thank the Royal Society for financial support of this work. J.A. Trevarthen gratefully acknowledges the support of the EPSRC under its ACCIS Doctoral Training Centre, Grant EP/G036772/1.
References (22)
Solid particle erosion of reinforced composite materials
Wear
(1981)- et al.
Solid particle erosion of polymeric coatings
Wear
(1981) - et al.
Erosive wear of composite materials
Wear
(1986) - et al.
Erosive wear studies of epoxy-based composites at normal incidence
Wear
(2008) - et al.
General method for predicting the sand erosion rate of GFRP
Wear
(2006) - et al.
Solid particle erosion of CFRP composite with different laminate orientations
Wear
(2009) - et al.
Sliding friction properties of carbon nanotube coating deposited by microwave plasma chemical vapour deposition
Tribol Int
(2004) - et al.
Investigation of tribological properties of polyimide/carbon nanotube nanocomposites
Mater Sci Eng, A
(2004) - et al.
The effect of carbon nanotube orientation on erosive wear resistance of CNT–epoxy based composites
Carbon
(2014) - et al.
Lightning strike protection of composites
Prog Aerosp Sci
(2014)
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