Metallic foams are a new type of material class using in the much-diversified area such as automotive, biomedical, and construction etc. Thanks to its porous structure, it stands out with its energy and impact absorption as well as its lightness. Due to the properties, metal foams have the potential for use in many applications. As the number of uses and potential applications increases, it becomes important to develop adequate joining technologies for metallic foams and to select appropriate methods for their widespread industrial use. However, various problems are encountered in welding metallic foams with a foam or a face sheet. The most important feature that causes differences in the welding process and characteristics of these materials is porosity. While the methods such as MIG/TIG could be preferred in the past, the methods such as laser welding have come to the fore with today's needs. The welding of metallic foams is a subject that is still being studied and developed. In this study, studies in the literature are examined to understand the problems encountered in metallic foams during welding and to develop welding techniques. It is aimed to create a wide source for the welding of metallic foams by referring to the methods used and the advantages and disadvantages of the methods with this review.

The release of aluminum (Al) and vanadium (V) ions represents a critical concern limiting the long-term performance and biocompatibility of Ti6Al4V-based permanent orthopedic implants. This study focuses on improving the corrosion resistance of Ti6Al4V alloys through the application of a novel organic–inorganic ZnO nanocoating. In addition, the present study investigated the influence of substrate roughness on surface morphology, microhardness, and wettability characteristics. Xanthan gum (XG) and celite (CE) were utilized as a biopolymeric–ceramic matrix for the ceramic–biopolymer-assisted synthesis of ZnO nanoparticles (ZnO NPs) through ultrasonication, which was subsequently followed by deposition onto Ti6Al4V substrates with varying surface roughness (Ra) achieved through controlled turning. The synthesized XG/CE-ZnO NPs exhibited a uniform spherical morphology with an average particle size of nearly 50 nm and a hexagonal wurtzite crystalline structure, as confirmed by TEM, XRD, and FTIR analyses. Contact angle (CA) measurements indicated that wettability increased with higher Ra, while SEM with energy-dispersive X-ray spectroscopy characterization revealed morphology transitions from smooth, homogeneous coatings to agglomerate, star-like nanostructures as Ra increased. Electrochemical testing in Ringer’s solution demonstrated a significant improvement in corrosion resistance after coating, with protection efficiencies ranging from 95.18% to 98.48%, particularly for smoother substrates. Although increased Ra may enhance coating adhesion through mechanical interlocking, smoother substrates promote the formation of more homogeneous coatings, resulting in superior corrosion protection. These results demonstrate the significant influence of substrate topography in enhancing the functional performance of biocompatible ZnO nanocoatings, providing valuable insights for the surface engineering of metallic implants.