Fatigue behavior of alpha-zirconium phosphate/epoxy nanocomposites

Abstract

Fatigue crack growth in ±-Zirconium phosphate/epoxy nanocomposites was investigated. A new fatigue testing technique was implemented for miniature samples. Two different methods “strength of materials and Rayleigh-Ritz - were used in determining the bending stress. The fatigue stress and fatigue life of different nanocomposite specimens were plotted in a traditional stress-life (S-N) curve. It was inferred from the S-N plot that the values obtained from both the methods compare well. The experimental results showed that fatigue life of filled epoxy nanocomposite is more than that of the unfilled epoxy composite. A model for bending stresses, ultimate strength and the number of cycles to failure was obtained to predict a component service life without conducting elaborate tests. Scanning electron examination of the fractured surfaces revealed that the crack takes a tortuous path during its propagation course, indicating crack blunting and crack deflection roles of ZrP and CSR nanofillers, which consequently improve the fracture resistance. In case of the M-ZrP-epoxy systems, delamination of ZrP platelets from surrounding epoxy matrix was proposed as the reason behind crack growth. The improved fracture resistance of these nanocomposites was attributed to the delamination of ZrP platelets and deflection of crack direction. The superior behavior of CSR-ZrP-epoxy composites was attributed to the cavitation process and void coalescence due to CSR particles delamination.