Silicon infiltration of silicon carbide selective laser sintered preforms

Barrow, Stacia Lynn
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High-temperature infiltration is an important process that is used to add strength to skeletal microstructures. In this study, silicon carbide preforms are created using selective laser sintering. These parts are then infiltrated with an epoxy to decrease slumping of the part. They are then infiltrated using high temperature pressureless infiltration of a silicon matrix. This materials system can be applied in a wide variety of industries, including military, aircraft, tooling and automotive. The silicon matrix adds strength to silicon carbide, is robust at high temperatures, and has a comparable coefficient of thermal expansion. Shrinkage measurements, optical microscopy, density measurements, four point bend testing, hardness testing, and scanning electron microscopy were all performed to characterize the parts. The silicon carbide/silicon parts had little shrinkage, were fully infiltrated, have good flexural strength. Flexural strength for non-epoxy silicon infiltrated parts was 147 MPa, and for epoxy silicon infiltrated parts, 163 MPa. Vickers hardness values for non-epoxy silicon infiltrated parts was 1400, and for epoxy silicon infiltrated parts, 1420. Scanning electron microscopy revealed that some undesirable reactions took place, but reaction bonded silicon carbide was formed.