Ultrafine-bubble-water-promoted nanoceramic decoration of metal powders for additive manufacturing

Abstract

The design of composite powders for exploiting the multifunctionality of metallic nanocomposites via laser additive manufacturing (AM) is challenging. Conventional ball-milling processes are prone to cause uncontrollable powder morphology and reduced flowability, while recently developed nanodecoration technologies are limited by complicated processing and impurity inclusion. Herein, a facile and scalable approach was developed using ultrafine bubble (UFB)-assisted heteroagglomeration to fabricate high-concentration, impurity-free nanoceramic/metal composite powders. Individual ZrO2 or Al2O3 nanoparticles up to ~10 wt% were homogeneously decorated on the surface of Ti-6Al-4V powders through the bridging effect of the negatively charged UFBs, leading to enhanced flowability and laser absorptivity. The nanoceramics were completely decomposed and dissolved into the matrix upon laser irradiation; therefore, a unique Ti nanocomposite exhibiting both high strength and ductility was obtained. Our work provides new insights into the application of UFBs and the fabrication of multifunctional AM components. Researchers have developed a novel ultrafine bubble-assisted heteroagglomeration (UFBH) method to economically fabricate high-concentration, impurity-free nanoceramic/metal powders for additive manufacturing. Using negatively charged UFBs, they successfully promoted the uniform decoration of positively charged nanoceramic particles on metal powder surfaces via electrostatic self-assembly. The resulting 1 wt% ZrO2/Ti64 component fabricated by laser powder bed fusion (L-PBF) exhibited a unique combination of high tensile strength and high ductility due to significant solid solution strengthening and grain refinement. This study introduces a facile and scalable approach using UFBH and laser AM processes to design multifunctional metallic components, paving the way for the production of novel composite powders and high-performance AM components. A facile and scalable approach was developed using ultrafine bubble (UFB)-assisted heteroagglomeration to fabricate high-concentration, impurity-free nanoceramic/metal composite powders for additive manufacturin. Individual ZrO2 or Al2O3 nanoparticles up to ~10 wt% were homogeneously decorated on the surface of Ti-6Al-4V powders through the bridging effect of the negatively charged UFBs. The nanoceramics were completely decomposed and dissolved into the matrix upon laser irradiation; therefore, a unique Ti nanocomposite exhibiting both high strength and ductility was obtained.