Fabrication of functionally graded reaction infiltrated SiC-Si composite by three-dimensional printing (3DP™) process

Carbon performs have been fabricated using the three-dimensional printing (3DP™) process for reaction-infiltrated SiC-Si composites. Starting with glassy carbon powders of 45-105 μm sizes, the preform was produced by printing acetone-based furfuryl resin binder. The bulk density and open porosity of the resulting preform was 0.6 g cm^-3 and 48%, respectively. The binder printing conditions during preform fabrication mostly determined the preform microstructure. Pressureless reactive infiltration of such preforms at 1450°C in nitrogen atmosphere formed a SiC-Si composite with a coarse-SiC grain structure. Some residual carbon remained inside the SiC grains in this reaction bonded SiC-C due to sluggish reactivity of the larger carbon powder particles. Relatively complex-shaped carbon preforms with overhang, undercut, and inner channel structures were produced, demonstrating the capability of the 3DP process. A functionally graded SiC-Si composite was also fabricated, by varying carbon-yielding binder dosage during the preform fabrication, in order to control the spatial SiC concentration within the SiC-Si composite.