Flexural Stress Homogenization Effects of Interfacial Transition Layers in Modified ZrB₂-Al₂O₃/Epoxy Composites

Abstract

The effect of interfacial modification on flexural strength of epoxy composites filled with modified ZrB₂-Al₂O₃ composite fillers was investigated in order to explore the stress distribution of modified composites under external load. The mechanical performance of epoxy composites filled with 0 vol%, 1 vol%, 3 vol% and 5 vol% unmodified and modified ZrB₂-Al₂O₃ fillers was characterized by three point bending (TPB) tests. The fracture surfaces of epoxy composites were observed by scanning electronic microscope (SEM). The results showed that the epoxy composite reinforced by 1 vol% modified fillers exhibited the optimal mechanical performance. According to the Von Mises stress contours simulated by finite element models (FEM) and the SEM images, it was shown that the modified ZrB₂-Al₂O₃ multiphase fillers could homogenize the stress in the epoxy composites due to the transition effect resulted from the interfacial modification layers on the surfaces of multiphase fillers. It contributed to the improvement of mechanical performance of epoxy composites further.

Keywords

surface modification / stress transfer / polymer-matrix composites (PMCs) / finite element analysis (FEA)

References

[1] Wetzel B, Haupert F, Zhang M Q. Epoxy Nanocomposites with High Mechanical and Tribological Performance[J]. Compos. Sci. Technol., 2003, 63: 2055-2067.

[2] Chen P, Li J, Zhang L. Analysis of Mechanical Characteristics of Fly Ash Cenospheres Reinforced Epoxy Composites[J]. J. Wuhan Univ. Technol.-Mater. Sci. Ed, 2018, 33: 139-145.

[3] Zhou Y, White E, Hosur M, et al. Effect of Particle Size and Weight Fraction on the Flexural Strength and Failure Mode of TiO₂ Particles Reinforced Epoxy[J]. Mater. Lett., 2010, 64: 806-809.

[4] Amaro A M, Bernardo L, Pinto D G, et al. Effect of Irregular Shaped Nanoalumina on the Enhancement of Mechanical Properties of Epoxy Resin Nanocomposites Using DDM as Hardener[J]. Compos. Part B, 2016, 84: 17-24.

[5] Wu Y C, Yu Z Q. Thermal Conductivity of in situ Epoxy Composites Filled with ZrB2 Particles[J]. in situ, 2015, 107: 61-66.

[6] Yu Z Q, Wu Y C, Wei B, et al. Boride Ceramics Covalent Functionalization and Its Effect on the Thermal Conductivity of Epoxy Composites[J]. Mater. Chem. Phys., 2015, 164: 214-222.

[7] Wu Y C, Yu Z Q, He Y N, et al. Heat Conduction Models of Interfacial Effects for TiB₂-Al₂O₃/Epoxy Composites[J]. Mater. Chem. Phys., 2015, 162: 182-187.

[8] Ivanez I, Santiuste C, Sanchez-Saez S. FEM Analysis of Dynamic Flexural Behaviour of Composite Sandwich Beams with Foam Core[J]. Compos. Struct., 2010, 92: 2285-2291.

[9] He Y N, Yu Z Q. Effect of Surface Organic Functional Modification of ZrB₂ Nanosize Multiphase Ceramics on the Thermal Properties of Its Composites[J]. Chem. J. Chin. Univ., 2015, 36: 1846-1852.

[10] Landel R, Nielsen L. Mechanical Properties of Polymers and Composites[M], 1993 Boca Raton: CRC Press.

[11] Nicolais L, Narkis M. Stress-Strain Behavior of Styrene-Acrylonitrile/Glass Bead Composites in the Glassy Region[J]. Polym. Eng. Sci., 1971, 11: 194-199.