EXTRUSION, DEBINDING AND SINTERING OF A COMMERCIAL PURE TITANIUM INK FOR ROBOCASTING

Abstract

Among additive manufacturing technologies, robocasting emerges as a versatile and an affordable method for processing metallic materials. However, the success and competitiveness of robocasting depend on the development of easy-to-process metallic inks that do not generate residues after debinding and production of high purity metallic parts. The additive manufacturing of titanium is in particular attractive and challenging. Titanium is a high-performance material with high specific mechanical strength, high fracture toughness, low elastic modulus, and high corrosion resistance with important applications in aerospace, marine, medical, alimentary, energy, recreational, and chemical industries. It is difficult to process titanium due to its high reactivity with oxygen and other elements that leads to the formation of oxides and brittle inclusions that impair the mechanical performance. The aim of this study is to understand the extrusion behaviour of a titanium ink and the debinding at different temperatures to obtain carbide- and oxide-free commercially pure titanium structures by robocasting. The results show that the ink meets all rheological requirements for robocasting allowing the fabrication of a variety of different titanium structures with a maximal unsupported span of 2 mm. Furthermore, the optimization of the debinding process avoided the thermal oxidation of titanium while maximised the elimination of the binder, showing superior efficiency than other binders studied previously. The microstructure and chemical analysis of the sintered samples confirmed the chemical and crystalline purity of the material.