Fabrication of textured cordierite ceramics with low thermal expansion coefficient and custom structure via vat photopolymerization

Abstract

Owing to the orientation of grains, textured ceramics possess particular properties along a specific direction. In this study, combining reactive template grain growth (RTGG) and vat photopolymerization, the textured cordierite ceramics with low thermal expansion coefficient (CTE) and custom structure were prepared successfully. Initially, the generation mechanism of the oriented c axis of α-cordierite grains in the XY plane was revealed by analyzing the evolution of microstructure during the sintering process. Then, two printing models were used to investigate the anisotropic CTE of porous cordierite ceramics fabricated by vat photopolymerization, indicating the effect of oriented grains and microstructure on the CTE. Finally, based on the selected dominant model, the controllable oriented microstructure was achieved by altering the shear stress provided by the scraper. The results showed that the oriented α-cordierite grains and skeletons were originated from the oriented tabular talc particles. Owing to the c axis of α-cordierite grains oriented in the XY plane, the CTE of the test direction parallel to the XY plane is lower than that perpendicular to the XY plane. In addition, with decreasing the setting layer thickness to adjust shear force, the oriented degree of tabular talc particles and α-cordierite skeletons became controllable. When the layer thickness reached a minimum of 25 μm, the CTE of porous cordierite ceramic reached the lowest of 1.26 × 10−6 K−1.