Investigating the effect of modified silica fume on the mechanical behavior of basalt fibers-epoxy composites under bending and tensile loading

Polymer matrix composites are one of the most widely used types of composites due to their lightness, and special strength and stiffness. Fibers-reinforced composites are the most important composites, and basalt fibers are one of the important types of mineral fibers that are used in the matrix of polymers. In this research, the effect of addition of silica fume particles (which has not been used in fibers reinforced polymer composites) on the mechanical properties of basalt fibers-epoxy composites under bending and tensile loadings was studied. The silica fume particles are surface modified with silane and then with different percentages (2, 4 and 6 wt.%) were distributed inside the epoxy matrix using a mechanical stirrer and ultrasonic waves. Hand lay-up method was used to make composite samples. The results of this research showed that with the addition of silica fume particles, the greatest improvement in the properties of the tensile strength and modulus, as well as the bending strength and modulus of the sample containing 4 wt.% silica fume is 22, 34, 27 and 40% respectively in compared to the sample without silica fume. On the other hand, the results of mechanical tests and microstructural examination after failure showed that the improvement of the interface between the fibers and the matrix as a result of the proper distribution of these particles inside the matrix has a significant effect on improving the mechanical properties. Also, the unfavorable distribution of these particles leads to the loss of mechanical properties under different loadings.