Surface modification of metallic powders plays a critical role in improving their chemical stability, interfacial characteristics, and processing behavior in powder metallurgy applications. In this study, micron-sized iron powders were treated using a controlled gas-phase phosphating process to investigate surface layer formation and microstructural evolution. The influence of treatment conditions on phase stability, surface morphology, and elemental distribution was systematically analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The results confirm the preservation of the body-centered cubic α-Fe phase within an optimized temperature range, while a conformal phosphate-based surface layer was successfully formed. Increased treatment severity led to partial surface oxidation and localized microstructural heterogeneity. Elemental mapping revealed homogeneous phosphorus distribution under controlled processing conditions, indicating uniform coating development. The study establishes clear correlations between gas-phase processing parameters and surface layer formation mechanisms. These findings provide insight into the controlled surface engineering of iron powders and offer practical guidance for optimizing gas-phase phosphating routes in advanced powder metallurgy and metallurgical applications.

Foodborne disease remains a major global health and economic burden, with recent World Health Organization estimates attributing roughly 866 million illnesses and 1.52 million deaths annually to 42 major foodborne hazards. Conventional preservation and decontamination strategies are increasingly challenged by antimicrobial‐resistant pathogens, chemical residues, and mycotoxin contamination, creating demand for complementary nanotechnology‐based interventions. Zinc oxide (ZnO) nanoparticles and their heterojunctions with graphitic carbon nitride (g‐C ₃ N ₄ ) have emerged as versatile platforms combining broad‐spectrum antimicrobial activity with visible‐light‐driven photocatalytic detoxification. This review synthesizes recent literature on the synthesis of ZnO nanoparticles by conventional and green/biogenic routes, including microbially mediated synthesis using actinobacteria such as Streptomyces species, and on the design of g‐C ₃ N ₄ /ZnO S‐scheme heterojunctions that suppress charge‐carrier recombination while preserving strong redox potentials. We examine the principal antimicrobial and photocatalytic mechanisms—reactive oxygen species generation, Zn ²⁺ ion release, and direct membrane interaction—and their translation into food‐relevant applications, including antimicrobial active packaging films and coatings, photocatalytic degradation of mycotoxins and pesticide residues, and nanomaterial‐based biosensors for pathogen and spoilage detection. Toxicological and regulatory considerations, including nanoparticle migration from food‐contact materials and evolving European Food Safety Authority and United States Food and Drug Administration frameworks, are discussed alongside persistent gaps in standardized safety testing, scale‐up reproducibility, and life‐cycle assessment. We conclude by outlining research priorities—particularly the systematic evaluation of biogenic ZnO and g‐C ₃ N ₄ /ZnO composites under real food matrices and regulatory‐relevant conditions—needed to advance these materials from laboratory demonstration toward safe, standardized, and sustainable adoption across the food value chain.