Optimizing Binder Selection for Reduced Contamination in Binder Jetting of Nickel Titanium Alloys

The fabrication of Nickel Titanium (NiTi) alloys through additive manufacturing (AM), particularly binder jetting, presents unique challenges due to residual contamination from binders, which can affect the final product's properties. This study evaluates various commercially available binders for their thermal decomposition characteristics and ability to minimize residual carbon content post-debinding. We mixed NiTi powder with selected binders (SPJ-04, Aquafuse, and PEI 800), cast the mixture into molds, and subjected the green parts to Thermogravimetric Analysis (TGA), ensuring uniform binder distribution and precise control over binder-to-powder ratios. <br><br>Through TGA, we identified binder compositions that demonstrated optimal decomposition and minimal contamination. Aquafuse exhibited the lowest residual weight when tested alone, while SPJ-04 had the lowest residual weight when interacting with NiTi powder, closely resembling the actual binder jetting process. SEM images provided further insights into the microstructure and the effectiveness of binder removal. <br><br>These findings emphasize the importance of binder selection in enhancing the quality of NiTi parts, achieving superior mechanical and functional properties. This approach provides a systematic method for optimizing binder compositions in binder jetting AM, offering time and cost savings. Furthermore, this refined methodology can significantly streamline the development process, facilitating faster innovation in critical fields like aerospace and medical devices, where high material integrity and performance are essential. The insights gained from this research underscore the potential for improving material properties and manufacturing efficiency through careful binder selection and process optimization.