Microwave Sintering of 3D Printed Composites from Polymers Reinforced with Titanium Nitride Particles

The production of intricate samples from polymer–ceramic composites employing fused deposition modeling was studied. The samples were subjected to high-temperature heat treatment in microwave furnaces to yield titanium nitride ceramics. The conditions for making polymer–ceramic materials from polypropylene and titanium nitride powders and 3D printing conditions for associated intricate parts were examined. The TiN–polypropylene composite was produced at a temperature of 190°C through extrusion of a previously prepared homogeneous mixture with a reinforcement content of 10, 20, 40, 46, 50, and 60 vol.% TiN. Using fused deposition modeling, a gear-shaped part made of the polymer–ceramic material was printed. The printed samples with 20 and 40 vol.% TiN were heat-treated in microwave furnaces in air in a carbon black backfill and in a nitrogen flow. Following the heat treatment in microwave furnaces, the samples preserved their initial shape. The composite samples treated in a carbon black backfill in air exhibited a porosity of ~38% and those treated in a nitrogen flow showed a porosity of ~22%. The samples subjected to microwave heat treatment in a carbon black backfill in air underwent sintering and partial oxidation. After microwave heat treatment in a nitrogen flow, the titanium nitride samples showed higher density and bimodal structure with titanium nitride grains varying from several micrometers to 400–200 nm. The microhardness of the samples heat-treated in a carbon black backfill was 6.5–8.5 GPa and that of the samples treated in a nitrogen flow was 16 GPa.