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Carbon fibre reinforced thermoplastics (CFRP) are intensively used in lightweight
applications due to their high strength to weight ratio. In addition they offer good crash,
damping and recycling properties. On the basis of their morphology they are suitable for large
scale manufacturing processes. A major disadvantage consists of its poor hardness properties,
which is again an important requirement to realize a good erosion and wear behaviour.
Design/methodology/approach: In this work the application of orthotropic carbon
fibre reinforced polymers (PA6), with protective TiAlN coatings, produced by physical
vapor deposition (PVD), is investigated. The characterization of the coating is performed
by nanoindentation tests, roughness measurements and scanning electron microscopy.
Furthermore micro hardness tests on selected well prepared cross sections are conducted,
to compare the coating quality with established coating systems.
Findings: By applying TiAlN coating, the hardness of the CFRP samples can be increased
substantially up to 15 GPa, in comparison to the basic substrate. In addition the quality of
the coating surface can be improved significantly by plasma etching pre-treatment.
Research limitations/implications: The presented findings are preliminary results to
prove the application of a standard processed ceramic coating on new composite types
for mass production. The PVD coating process as well as the utilized testing methods are
suitable to realize hard coatings on thermoplastic CFRP. This effect can be exploited for
several lightweight applications to increase the erosion and wear resistance of composite
materials.
Originality/value: The presented results show, that ceramic coatings can be deposited
on standard thermoplastic CFRP with polyamide 6 matrix. Therewith it can be expected,
that the PVD coating process can make a essential contribution to increase the range of
applications.
Multi-layer constructions become more and more relevant in lightweight applications due to their high strength to
weight ratio. They offer excellent crash, damping and recycling properties. Also, the morphology of thermoplastic
carbon fibre reinforced plastics (CFRP) render them interesting for large scale manufacturing processes.
Nevertheless, a major disadvantage results in a poor resistance against wear and tear, e.g. erosion, which is
attributed to weak hardness properties. Hence, this work deals with tribological investigations on orthotropic
carbon fibre reinforced polymers (PA 6) either with protective ceramic coating or without. The chosen coating
system is a well-known protective covering of metal components, e.g. metal cutting tools, produced by physical
vapor deposition (PVD). To characterize the coating system on thermoplastic CFRP, standard analyzing methods are utilized, like optical and scanning electron microscopy (SEM). The tribological investigations are conducted by the tribological ball on disk method to generate wear tracks on the sample surfaces and hence to calculate the
wear rates. These results are compared to literature findings with respect to a certain protective coating system (TiN) and a second nano-structured gel coating system, where both systems are deposited on a thermosetting
material, i.e. carbon fibre reinforced epoxy resin, respectively. For this purpose the feasibility of depositing a protective ceramic layer on thermoplastic CFRP is demonstrated. First results on suitable surface pre-treatments have shown a significant influence on the coating quality. The improved performance regarding the wear behavior with respect to tribology compared to the poor substrate and existing technologies is shown additionally.
The current trend shows an increasing demand for composites due to their high stiffness to weight ratio and the recent progress in manufacturing and cost reduction of composites. To combine high strength and stiffness in a cost-effective way, composites are often joined with steel or aluminum. However, joining of thermoset composite materials is challenging because circular holes are often used to join them with their metal counterparts. These design based circular holes induce high stress concentration around the hole. The purpose of this paper is to focus on layup configuration and its impact on notch stress distribution. To ensure high quality and uniformity, the holes were machined by a 5 kW continuous wave (cw) CO2 laser. The stress distribution was evaluated and compared by using finite element analysis and Lekhnitskii’s equations. For further understanding, the notch strength of the laminates was compared and strain distributions were analyzed using the digital image correlation technique.
In this paper the relationship between surface energy and flexural strength of metal laminate made by reinforcing glass fibre reinforced polymer on steel surfaces was investigated. Sand blasting was performed on 22MnB5 steel surface. This steel was stacked together with layers of unidirectional glass/polyamide-6 prepreg, followed by pressing in a hot press. Influenced parameters are pressure, temperature and time. 3D profilometer analysis was used to investigate the roughness profile on the surface of the steel generated by the sand blasting. The surface energy of the steel surface was calculated from a set of contact angles measured by three different liquids. To identify the optimal surface treatment, the variation of surface energy, flexural strength and roughness of the steel surface was determined as function of the surface treatment. Surface roughness (Ra of 1.08 μm), results indicate that increasing surface roughness leads to improvement in flexural modulus. The increase further leads to decrease in flexural modulus. In addition, the influence of surface energy and flexural strength on the impact damage behaviour was investigated too. The results showed that the sample with highest flexural modulus had the lowest impact-induced damage area.