Thermal Characterisation of Binder Constituents and Wax-Based Aluminium Metal Injection Moulding Feedstock for Micro-Metal Parts

Abstract

Thermal decomposition behaviours of the binder constituents have been identified to influenced the quality of metal injection moulding (MIM) feedstock and sintered parts. This research investigates the thermal characterisation of the binder constituents and wax-based aluminium MIM feedstock. The binder system is composed of paraffin wax (PW) – 65 wt.%, high density polyethene (HDPE) – 30 wt.% and Stearic acid (SA) – 5 wt.%. While, the wax-based aluminium MIM feedstock is formulated with the proportions of the binder constituents and 99.999% pure aluminium powder at solid loading of 62 vol.%. Thermal characterisation technique employed for the evaluation of the binder constituents and wax-based aluminium MIM feedstock were differential scanning calorimetry and thermogravimetric analysis (TGA). Significant changes were observed for the binder constituents at various temperatures 45 °C and 60 °C (PW), 135 °C (HDPE), 75 °C (SA) and 45 °C, 60 °C, 135 °C (Wax-based aluminium MIM feedstock) on the DSC profiles. While TGA results revealed that binder constituents can be removed completely around 580 °C from the wax-based aluminium MIM feedstock. Thermal behaviour of the binder system established will be useful for setting suitable injection moulding temperature, development of the thermal profile(s) for debinding and sintering processes of the aluminium MIM micropart production.