DLP 3D PRINTING OF CORUNDUM CERAMICS: DEVELOPMENT OF TEMPERATURE-TIME FIRING MODES AND PHYSICAL MECHANICAL PROPERTIES OF SINTERED CERAMICS OBTAINED BY THE ADDITIVE METHOD

The paper shows the use of projection stereolithographic 3D printing by digital light processing (DLP) to produce VTC-95-1 corundum ceramics. Based on data from thermogravimetric (TG) and differential scanning calorimetric (DSC) analyses, temperature regimes of debinding and clinkering have been developed. It is shown that graded debinding with a heating rate of 0,4...0,5 °C/min and exposures at 300, 375 and 470 °C, as well as subsequent clinkering at 1600 °C, ensured the achievement of a relative density of up to 95 % of the theoretical (3,47 ± 0,02 g/cm3). The water absorption was 0,69 ± 0,19 %, which indicates the predominance of closed porosity in sintered ceramics. The tensile strength during three-point bending of sintered samples ranged from 180 to 250 MPa, depending on the orientation of the layers relative to the loading vector: the maximum values (250 ± 30 MPa) were placed on record when exposed to a load along the printing axis. The Vickers hardness was 850 ± 25 HV. According to the results of the microstructural analysis, it was found that the developed heat treatment mode ensures the complete removal of the polymer binder and provides the production of sintered ceramics with a uniform grain size distribution, with an average grain size of 5,1 microns. Thus, the totality of the results obtained confirms the applicability of the considered additive method for forming the geometry of VTC-95 corundum ceramics.