Over-infiltration mechanisms in selective laser sintered Si/SiC preforms

摘要

Purpose - The paper aims to evaluate mechanisms for silicon overfilling including volume expansion of silicon on solidification for composite silicon/silicon carbide (SiC) objects generated using post-process infiltration of selective laser sintered (SLS) SiC preforms. Design/methodology/approach - Overfilling was characterized through geometrical means and microscopy, and results were used for further study and discussion of overfilling mechanisms. Findings - Silicon overfilling in silicon infiltrated SLS SiC parts is attributed primarily to its infiltrant silicon volume expansion on solidification. Si/SiC composites were found to be thermally stable with good material bonding. Research limitations/implications - Silicon as an infiltrant is unusual as it expands on solidification, whereas most infiltrants contract. Overfilling during infiltration of SLS porous performs is therefore not considered to be prevalent. Originality/value - This paper provides an examination of the value of silicon as an infiltrant material for SLS SiC preforms. Various mechanisms are presented for volume change during post-process infiltration of indirect SLS non-metallic performs.