On the interfacial adhesion of fiber metal laminates using surface modified aluminum 7475 alloy for aviation industries – a study

Abstract

Aluminum-based hybrid laminates are used extensively during the fabrication process of structural components in aviation industries due to its light weight and mechanical properties. A majority of airframe components are usually fitted with adhesion joints and, hence, surface adhesion has a great deal with surface and subsurface properties. To promote adhesion between substrates, various surface activating techniques could be followed. The main objective of this work is to enhance the interfacial adhesion strength between the thin aluminum alloy (AA 7475) and glass fiber. Experimentation was carried out to monitor the increase in the interfacial adhesion, by investigating the change in surface free energy which is influenced by the effect of surface etching. Aluminum sheets were treated using alkali (NaOH), iron (III) sulfate (Fe2(SO4)3) and potassium dichromate (K2Cr2O7). Etching effects were analyzed using water contact angle (WCA), profilometry, scanning electron microscope (SEM images), X-ray diffractometer (XRD) and Fourier transformed infrared spectroscopy (FTIR-ATR). Tensile strength testing was done to evaluate the interfacial adhesion strength. The outcome of experimentation proves that, iron (III) sulfate treated condition laminates have higher tensile strength and it has also increased the interfacial adhesion.