Surface chemistry characterization of AA2014 aluminum alloy powder through triboelectric charging

Traditional characterization techniques for powders primarily focus on bulk properties, often neglecting the critical role of surface chemistry variations that influence the performance in applications such as additive manufacturing. The method presented in this work addresses this gap by utilizing triboelectric charging concept to gain a comprehensive understanding of powder surface state under varying environmental conditions. In particular, the study investigates the detection of surface chemistry variations of AA2014 powder caused by an exposure to various relative humidity (RH) levels through a change in triboelectric charging behavior. The surface variations are analyzed in parallel with X-ray photoelectron spectroscopy (XPS). The findings reveal a direct correlation between elevated RH and increased hydroxide species content at the surface of the powder. The triboelectric charging experiments demonstrated a significant RH-dependent variations of charge accumulation, with higher humidity levels leading to reduced static charge buildup on the powder particles. The charge accumulation behavior in the powder was fitted with the compressed exponential relaxation model. The results showed that each surface chemical species exhibits a distinct correlation between charging rate and charge accumulation, confirming the effectiveness of the method to detect subtle variations in surface chemistry. The variations in the exponent of the fitted model were shown to be characteristics to the surface scale of the powder particles.