Production of alumina parts by powder injection molding with a binder system based on high density polyethylene

In this experimental work, injection molding of alumina parts was performed with a developed binder system based on high density polyethylene (HDPE), paraffin wax (PW) and stearic acid. Firstly, the optimum binder composition was determined by torque measurements and rheology. Alumina feedstocks with powder loadings between 50 and 60% in volume were prepared with the developed binder system. A suitable formulation for powder injection molding was chosen based on torque measurements, rheological behaviour and homogeneity of feedstocks. All the feedstocks studied exhibited a pseudoplastic behaviour with flow behaviour index n < 1. Feedstock with 58 vol.% solid loading exhibited the most suitable behaviour for ceramic injection molding and was chosen to perform the complete process. Debinding cycle was designed based on thermogravimetrical analysis and differential scanning calorimetry. The best results were found using solvent debinding followed by thermal debinding. Final parts had densities close to 99% after sintering at 1600 °C during 2 h.