Binder jetting advanced ceramics for metal-ceramic composite structures

Metal Matrix Composites (MMCs) are a class of materials combining two dissimilar materials (e.g., metal & ceramic) that when combined, provide unique properties including low density, high specific strength, high specific modulus, high thermal conductivity, and wear resistance and can be used in range of applications including high-temperature applications, structural applications, and can act as crack arrestors in fatigue applications. However, MMCs are not widely adopted due to their high cost and are limited in the geometrical configuration of the ceramic cores (e.g., extrusion, tiles, stochastic foams, etc.). In this work, the authors proposed a novel process protocol that takes advantage of the geometrical freedom offered by Additive Manufacturing (AM). Specifically, the authors look to print a complex ceramic structure from precursor powders via Binder Jetting AM technology to incorporate into a bonded sand mold and the subsequently casted metal matrix. The manufacturing process for creating a successful MMC is divided into two distinct steps: i) determination of the printing parameters, pre-and-post sintering ceramic characterization, and ii) molding, casting, and testing MMCs. Through sintering experiments, a sintering temperature of 1375 C-ay was established for the ceramic insert (70 % cordierite). Upon printing and sintering the ceramic, three-point bend tests showed the MMCs had less strength than the matrix material likely due post-processing and geometrical effects, effects of gravity casting, and relatively high porosity developed in the body. It was found that the ceramic metal interface had minimal mechanical interlocking and chemical bonding limiting the strength of the final MMCs. Furthermore, the authors provide directions for future work on how to successfully utilize the proposed manufacturing process to create printed MMCs with more effective properties.