Effects of Metal Surface Treatment on the Interfacial Strength in Magnesium Alloy-Based Fiber Metal Laminates

Abstract

Magnesium alloy-based fiber metal laminates (FMLs) represent a novel composite type, increasingly recognized for their potential in high-performance engineering applications, particularly in the aerospace and automotive industries. A strong bonding interface is a key factor in improving the durability of these laminates; to achieve this, appropriate surface treatments of the magnesium alloy sheets need to be applied.

The study aims to compare different metal surface treatments, specifically phosphating and sandblasting, to enhance the interfacial strength between the metal skins and the composite core of the fiber metal laminates. The morphology, composition, and surface energy of the differently treated metal surfaces were analyzed using scanning electron microscopy, chemical analysis, and measurements of wettability and roughness. Subsequently, the resistance of the interfacial strength was evaluated through lap shear tests under mode II loading conditions. After mechanical testing, the characteristics of the fractured surfaces were analyzed.

Although the FML samples with phosphatized metal surfaces exhibit a less defective interface than those with sandblasted metal surfaces, they are characterized by a lower mechanical strength. This behavior is attributed to the premature peeling off of the phosphating layer from the magnesium alloy sheets. With the gained insights, further research avenues open up towards optimized interfaces for FML components.