Keleş, Abdulsamet; Karabudak, Filiz; Acar, Volkan; Kula, M. Emin; Aslan, Mustafa; Karabacak, A. Hasan; Alibeyoğlu, Fatih

Metal plate core-based sandwich composites have the potential to revolutionize various industrial fields due to their mechanical strength and vibration damping. In this study, AZ91 (a magnesium alloy) and Al1050 (an aluminum alloy) metal core-based sandwich composites of AZ91/carbon fiber-epoxy, AZ91/glass fiber-epoxy, Al1050/carbon fiber-epoxy, and Al1050/glass fiber-epoxy sandwich composites were manufactured. These composites' mechanical and dynamic properties were determined through tensile, three-point bending, and vibration tests. AZ91-reinforced carbon fiber composites exhibited a 28.8% higher tensile strength than glass fiber composites, while Al1050-reinforced carbon fiber composites showed a 17.2% higher tensile strength performance than glass fiber composites. Moreover, AZ91 reinforcement led to composites with higher average flexural strength for both fibers. In vibration tests conducted under clamped and free-free boundary conditions, the highest first natural frequency was observed in AZ91/carbon fiber samples, sparking further interest. Conversely, the highest first damping ratio was observed in Al1050/glass fiber specimens. In addition, the corrosion behavior of sandwiches was evaluated, and it was found that glass fiber provided better corrosion resistance than carbon fiber. Highlights: Sandwich composites comprising AZ91/Al1050 cores and carbon/glass fiber reinforced epoxy face sheets were manufactured. Galvanic corrosion effects were evaluated, and glass fiber was found to provide higher corrosion resistance. AZ91/carbon fiber sandwich showed 28.8% higher tensile strength than glass fiber. Vibration tests revealed the AZ91/carbon fiber sandwich had the highest first natural frequency. Al1050/glass fiber sandwich exhibited the highest first damping ratio.

Alibeyoğlu, Fatih; Karabudak, Filiz; Yeşildal, Ruhi; Balcı, Arif; Efeoğlu, İhsan; Ateş, Onur Kazım

Despite their extensive use in the automotive and aerospace industries, Mg and Mg alloys, which are light metals, exhibit low fatigue and tensile strength. In this study, transition metal-nitride (TMN) multilayer coatings (Ti+TiN+Ti+TiVN) were coated twice on AZ91 Mg alloy using a Confined Field Unbalanced Magnetron Sputtering (CFUBMS) system to increase fatigue and tensile strength. The structural properties of the films were analyzed by using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometry (EDS) methods, and the mechanical properties were analyzed by rotating bending fatigue and tensile testing machines. Ti+TiN+Ti+TiVN multilayer nitride surface coatings on AZ91 Mg alloys showed a dense and columnar microstructure and according to XRD results (111) was the preferred orientation with the dominant peak. The fatigue limit value of the AZ91 base material was fixed at 60.46 MPa, while it increased to 68.48 MPa after being coated with multilayer nitride. Along with the multilayer nitride coating, the tensile strength increased from 169.98 MPa to 175.43 MPa. As a result, the multilayer hard nitride coating with low surface roughness, which fills the defects, notches, and voids on the surface of the AZ91 base material, increased the fatigue and tensile strength in parallel. Based on the outcomes of the research, the literature has been enriched with an innovative approach through the enhancement of fatigue and tensile strengths by applying a CFUBMS coating to lightweight metals and alloys, such as AZ91, especially in the transportation industry where lightness and dynamic load resistance are essential.