Removal of the water soluble binder components from titanium and titanium alloy powder compacts produced by MIM

Abstract

This work investigates the debinding process of powder compacts formed by metal injection moulding (MIM) of feedstocks comprised of HDH Ti or HDH Ti-6Al-4V powder mixed with a binder of a predetermined ratio of water soluble polyethylene and wax. The full debinding process has three stages: a solvent debinding process to leach the water soluble component, a drying phase allowing the removal rate to be measured and a thermal treatment step for removing the wax components, leaving the backbone components to retain part geometry prior to sintering. Leaching of the water soluble component was monitored and the results were consistent with the general correlation which predicts that binder removal time increases by a factor of 4 when the section thickness is doubled. Uniformity of binder removal, defect formation and particle surface degradation in Ti MIM parts are also discussed.