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The paper presents the characteristics of Ti-Mo-xTiC composites manufactured under experimentally selected conditions using the upgraded field-assisted sintering technique (U-FAST). Mixtures of microstructural titanium powders and nc-Ti0.9Mo0.1C/C carbide powders protected from oxidation by a carbon shell were subjected to sintering. The powders with nc-Ti0.9Mo0.1C/C contents of 10 and 20 wt% were used. The content of carbon forming the carbon shell was approximately 3 or 40 wt%. Composites with near full density were reinforced with titanium carbides in a Ti-Mo matrix. The composites with the highest content of reinforcing phase are characterized by the highest values of hardness, Young's modulus and wear resistance. Although the hardness of these composites is similar to that of ceramics, their nature is not brittle. Despite the high value of the Young's modulus, the addition of hard particles of the reinforcing phase to the titanium matrix significantly increases the values of the H/E ratio of the composites compared to the reference samples of cp-Ti and Ti6Al4V. A comparison of the research results for the composites with the highest share of titanium carbides showed that lowering the sintering temperature from 1300 to 1150 °C resulted in the inhibition of grain growth, a reduction in composite heterogeneity, composite roughness and hardness as well as a rise in the Young's modulus. An increase in the sintering temperature from 1150 to 1300 °C contributed to the higher high angle grain boundaries (HAGB) content.
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.