Development and Investigation of AlSi12-Based Composites Reinforced with SaffilTM Fibers and Nickel-Coated Graphite Flakes

Composites based on the AlSi12 aluminum alloy reinforced with Saffil^TM fibers (Composite I) and with both Saffil^TM fibers and nickel-coated graphite flakes (Composite II) were developed using the squeeze casting method in the fabrication process. The objective of this work was to evaluate the influence of the employed reinforcements on the mechanical properties and corrosion behavior of the obtained materials. To achieve this, investigations were conducted, including SEM analysis, flexural strength testing, Brinell hardness testing, linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Corrosion measurements were performed in a 3.5% NaCl solution at room temperature. Mechanical investigations revealed a significant increase in flexural strength and hardness for Composite I compared to the plain matrix alloy. In contrast, Composite II's flexural strength was reduced by the weakening effect of graphite flakes. Performance under bending improved by 46% for Composite I and 25% for Composite II compared to the AlSi12. The corrosion resistance of the tested materials followed the order AlSi12 > Composite I > Composite II. The LSV and EIS results indicate that the explanation for this may be differences in the properties of the protective oxide/hydroxide layer. Furthermore, SEM images showed a weak bond between nickel and graphite.