Powder effects in SiC matrix layered structures fabricated using selective area laser deposition vapor infiltration (SALDVI)

Abstract

Silicon carbide has been deposited by laser-induced chemical vapor infiltration from the gas precursor tetramethylsilane, Si(CH3)4, into loosely packed powder layers of SiC, ZrO2-Y2O3, or Mo. The goal is to produce dense layered structures of arbitrary shape by computer controlled laser scanning where the pore spaces between the powder particles are filled with solid material deposited from the gas phase using the selective area laser deposition vapor infiltration (SALDVI) process. Layered samples were fabricated for each powder material using both single line (bar) and multiple line (slab) laser scan patterns and 10 Torr Si(CH3)4, 2.5 μm/s scan speed, 1000°C target temperature, and 120 μm layer thickness. Samples of SiC and ZrO2-Y2O3 are prone to surface cracking in the bar geometry, and cracking and delamination of layers in the slab geometry. Samples fabricated with Mo powder have no cracks or delamination defects in either bar or slab geometry as well as a better surface appearance.