Homogeneity of microwave sintering of large porcelain objects shaped by robocasting
Résumé
The application of additive manufacturing (AM) technologies, such as robocasting, can be used to produce technical and architectural ceramic parts for a variety of applications in a range of sectors, including the craft industry [1]. AM opens up and enriches the possibilities for craftspeople, helping them to create innovative forms. Robocasting can be used to produce parts from traditional ceramics such as porcelain. This technology can be combined with non-conventional sintering processes such as microwave (MW) sintering. MW sintering offers the possibility of speeding up the manufacturing process by allowing higher heating ramps to be achieved. Studies on MW sintering have focused on the sintering of small pellets. This study aims to determine the homogeneity of densification by MW sintering for larger parts with complex shapes. After printing the commercial porcelain paste, the parts were dried and sintered. A multimode MO cavity was used to accommodate larger parts. Two identical parts were placed in two different orientations (vertical and horizontal) in a crucible made of thermal insulators (RATH®) and SiC plates. In a previous study [2], thermal cycles were optimised on porcelain pellets formed by robocasting. The same thermal cycles were used in this study : temperature ramp of 50°C/min, temperature plate of 1300°C for 30 minutes. In order to obtain the most accurate characterisation of the densification homogeneity, the parts were cut into several pieces. These pieces were characterised : measurement of the 2D porosity rate using an optical microscope, measurement of the density by Archimedes weighing and measurement of the Vickers hardness. The main parameters influencing the MW sintering process were studied : the microwave power delivered to the cavity and the positioning of the part in the crucible. The results show that the positionning in the crucible has an influence on the characteristics of the final part. References [1] C. Marquez et al., « Direct Ink-Write Printing of Ceramic Clay with an Embedded Wireless Temperature and Relative Humidity Sensor », Sensors, vol. 23, p. 3352, mars 2023, doi: 10.3390/s23063352. [2] M. Peroglio, C. Meunier, J. Favre, J. Faucheu, et C. Petit, « A parametric study of conventional and high-speed microwave sintering of robocast porcelain », Open Ceram., vol. 9, p. 100246, mars 2022, doi: 10.1016/j.oceram.2022.100246.