3D Printing of MoSi2-Based Ceramic Heaters Using the Robocasting Method

The robocasting method is a promising and innovative approach to the layer-by-layer manufacturing of complex-shaped products. Its prospects for printing MoSi₂ ceramics by extruding a paste with a high content of solid particles (ceramics, metals, fibers, etc.) and a plasticizer to build a product layer by layer were demonstrated. A 10 wt.% solution of rubber in gasoline was chosen as the plasticizer. A comprehensive process was developed for the full cycle of manufacturing samples of heating elements, ranging from the preparation of molybdenum disilicide powder pastes to the sintering of the product in a vacuum furnace and the determination of its physical, mechanical, and electrical properties. The influence of the scale factor (variation in the size of a single printed layer) on the features of printing with the robocasting method was studied. The relationship between nozzle diameter/layer thickness and paste composition (MoSi₂ powder and plasticizer) was established. The operating range of the plasticizer content for printing with nozzles having a diameter of 0.84–3 mm was found to be 12–17 wt.%. Analysis of the rate at which the plasticizer content reduced in the preparation and transportation of the paste, caused by the evaporation of volatile components, showed that the time for preparing the paste should not exceed 5 min. Samples produced by the robocasting method were heat-treated in a vacuum drying oven at 350°C for 2 h and consolidated in a vacuum furnace at 1900°C for 1 h. X-ray diffraction performed at all production stages revealed changes in the composition of the sintered samples, including the formation of up to 15 wt.% of the Mo₅Si₃ phase. The sintered samples were tested for electrical and mechanical properties. In the determination of current–voltage characteristics, the samples were heated to 90°C at a power of approximately 1 W. The Vickers hardness was 9.5 ± 1.4 GPa.