Friction and wear properties of graphite/SiC composites built by SLS

Abstract

This paper integrates Selective Laser Sintering (SLS) with Liquid Silicon Infiltration (LSI) to fabricate graphite/SiC composite materials. The graphite content is modified through multiple cycles of impregnation carbonization and graphitization. The results indicate that the microstructure of the composite materials significantly influences their tribological properties as the graphite content increases. When the graphite content is below 7.86 vol%, SiC forms a three-dimensional dual-continuous structure. The limited wear debris on the friction surface results in a relatively high average coefficient of friction (COF). Conversely, when the graphite content exceeds 79.83 vol%, a unique "sandwich" structure develops between the graphite and SiC. With this specific microstructural change, the average COF of the composites not only did not decrease but actually increased, while the mechanical properties gradually diminished and the thermal properties gradually improved. When the graphite content is within the range of 22.75 vol% to 34.59 vol%, the composite materials exhibit a lower average COF (0.26 ∼ 0.17) and wear rate (0.73 ∼ 6.69 × 10⁻⁶·mm³·N⁻¹·m⁻¹). By regulating the graphite content, the application range of the composite materials is broadened. This research lays the groundwork for future investigations into more complex factors affecting SiC ceramic composite materials.