Outdoor-weathering durability of polyamide composites in firearm-frames via plasma activated ceramic coatings

Glass fiber–reinforced polyamide 66 (PA66-GF) composites are widely used in critical applications such as plastic firearm frames owing to their low density, favorable mechanical properties, and relatively high tribological resistance. However, long-term exposure to UV radiation, humidity, and temperature fluctuations can significantly degrade the surface and fiber–matrix interface, thereby reducing performance and service life. As such, increasing the natural weathering resistance of PA66–GF composites is imperative. In this study, it is tested whether a plasma-assisted Ceramic Coating (Cerakote) process improves protection from environmental degradation. The uncoated samples withered after approximately 3 months and showed microcracks, matrix degradation, and oxidation, whereas the coated samples showed no critical microstructural changes over the aging stage. The mechanical characterization demonstrated the coating was advantageous; at 3 months postcoated aging both coated and uncoated samples demonstrated a tensile strength of 80 MPa and 66 MPa respectively, an enhancement of above 20%. At six and nine months of aging, this pattern persisted. In addition, the coated samples exhibited approximately 50% higher wear resistance than the uncoated samples after 3, 6, and 9 months of aging.