Innovative Chemical Approach for Powder Declogging of Internal Channels of Metal am Parts

Metal additive manufacturing (AM) has made rapid advancements, but surface-related defects (SRDs) like roughness, waviness, partially sintered powders, and near-surface porosity remain significant challenges, particularly in internal channels. These defects disrupt fluid dynamics, reduce cleanliness, and impair component performance. Internal channels also clog due to trapped powder, often rendering parts unusable. Few solutions exist for removing this trapped or partially sintered powder from internal channels and cavities. In this work, we are testing a chemical-flowing approach to remediating clogged channels and improving surface texture and cleanliness. The method employs specially designed chemistry with selective reactivity towards the unfused powder while being weak enough to avoid damaging the fused material. This self-limiting reaction does not continuously dissolve the fused material, as in traditional chemical milling, but effectively reduces and dissolves powder particles to unclog channels. Following this, a chemical polishing (CP) formulation is applied to improve the surface roughness of internal passages further. Although still ongoing, our findings demonstrate that this approach can significantly enhance internal surface quality, improving fluid dynamics, cleanliness, and overall performance of metal AM components. The process has been tested on single and multi-channel systems and complex gyroidal heat exchangers with varying sizes of internal diameters (IDs). Materials tested include AlSi7Mg, IN-718, and Ti-6Al-4V, all of which showed marked improvements after treatment. This technique addresses high levels of SRD remediation and surface planarization, offering a comprehensive solution for optimizing internal channels in AM components. The study was funded by the USAF (SBIR-FA864923P0707 and FA864922P0969).