This work investigates the hybrid fiber sequence effect on the flexural and impact properties of basalt/carbon epoxy composites. In the present study, six configurations of composite laminates were fabricated by vacuum-assisted resin transfer method and tested in three-point bending and Charpy impact tests. The results show that hybrid composites outperform pure basalt or carbon laminates. The maximum flexural strength and modulus, such as in [C₂B₄C₂], were realized for the configurations with carbon fibers on the outer layers because of the rigidity of carbon. However, higher energy absorption was offered by the basalt-rich composites because of their ductility. Among the hybrids, a balanced stacking sequence like [C₄B₄] and [B₂C₄B₂] showed an optimum between stiffness and toughness. Flexural modulus was maximum at 12.1 GPa for carbon-dominant layers, whereas impact resistance was maximum for alternating hybrid layers at 120 kJ/m². SEM analysis revealed that the dominant mechanisms of failure were delamination at the fiber–matrix interface and fiber pull-out, while the stacking order was critical regarding stress distribution. Hybridization also increased cost-performance metrics by a factor of 40%, as basalt fibers reduced the cost while maintaining acceptable mechanical properties. These results prove the potential of basalt-carbon hybrid for applications requiring high strength, impact resistance, and economic efficiency.

Polymer composites have been widely used in industrial applications because of their high-specific strength and modulus. During their maintenance and service life small scratches can be formed on the surface of the composite material. These small scratches can result in crack initiation causing material failure and also some esthetic defects. When we consider that polymer composites may have various fiber orientations, it is possible to develop a remarkable increase in their scratch resistance. For this reason it is necessary to investigate the effect of fiber orientation on scratch resistance for polymer composites. In this study, scratch resistance of continuous carbon-fiber-reinforced polyetherimide composites were investigated as a function of fiber orientations by means of CSM microscratch tester machine. During the experiments the relation between the scratch resistance and operational parameters are determined as a function of scratch hardness, penetration depth, and coefficient of friction.