Additive manufacturing of SiO2–Al2O3 refractory products via Direct Ink Writing

Abstract

The Direct Ink Writing (DIW) method is an approach for fabricating refractory products with complex shapes in an efficient and cost-effective manner. This study investigated the influence of printing parameters on the performance of Al2O3 refractory products prepared via DIW. It was found that the layer height is an effective parameter for tuning the inter-space size and the adhesion between layers, under constant extrusion rate and distance between the deposited filaments. The inter-space size could be eliminated by decreasing the layer height to 1.0 mm (i.e., 50% of the nozzle diameter); the flexural strength was enhanced from 45 MPa to 61 MPa when the layer height decreased from 1.8 mm (i.e., 90% of the nozzle diameter) to 0.8 mm (i.e., 40% of the nozzle diameter). Changing the layer height led to a deviation in printing, this deviation could be eliminated by optimizing the travel speed of the nozzle. At a layer height of 0.8 mm, the size deviation could be reduced from 10.5% to 0.59% when the nozzle travel speed changed from 35 mm/s to 70 mm/s. Consequently, there was a considerable improvement in the printing efficiency. These results indicate that, owing to their dense microstructures, samples prepared at a layer height of 0.8 mm exhibit superior slag resistance and a high flexural strength of 61 MPa after sintering at 1600 °C for 3 h.