Digital light processing additive manufacturing of in situ mullite-zirconia composites

Digital light processing (DLP) can produce small series ceramic parts with complex geometries and tiny structures without the high cost of molds usually associated with traditional ceramic processing. However, the availability of feedstock of different ceramics for the technique is still limited. Mullite-zirconia composites are refractory materials with diverse applications, nevertheless, their 3D printing has never been reported. In this work, alumina and zircon were used as raw materials for additive manufacturing by DLP followed by in situ mullite and zirconia formation. Thus, coarse zircon powder was milled to submicrometric size, alumina-zircon photosensitive slurries were prepared and characterized, parts were manufactured in a commercial DLP 3D printer, debound, and sintered at different temperatures. The printed parts sintered at 1600 °C completed the reaction sintering and reached a flexural strength of 84 ± 13 MPa. The process proved capable of producing detailed parts that would be unfeasible by other manufacturing methods.