Formulating titanium powder feedstocks for metal injection moulding from a clean binder system

Impurity control is paramount in achieving success in titanium metal injection moulding (Ti-MIM), primarily due to Ti being a universal solvent for interstitial elements such as oxygen and carbon. This study developed a clean binder system with a low decomposition temperature based on polypropylene carbonate/polyoxymethylene (PPC/POM). However, due to the poor shape retention of the PPC/POM binder system, polyethylene glycol (PEG) was incorporated to facilitate the formation of a porous network within the compact structure, allowing efficient removal of residual binder for subsequent debinding process. The results reveal that increasing the PEG content leads to a higher binder removal rate, while adding POM enhances shape retention during debinding. The optimal PEG/PPC/POM binder system compositions were identified as 40/48/10% w/w, respectively, offering a higher PEG removal rate and improved shape retention. Lastly, the resultant debound titanium feedstock from this novel binder system showed low impurity contents, complying with ASTM F2989 requirements.