Laser powder bed fusion as a net-shaping method for reaction bonded SiC and B₄C

Additive manufacturing (AM) technologies for technical ceramics are rapidly emerging. Many of these processes rely on a polymer binder-assisted printing approach followed by de-binding and furnace sintering for densification. However, the required de-binding step is long and sensitive, and the presence of densification shrinkage requires a compensation in design. This study explores laser powder bed fusion (LPBF) as an additive manufacturing method for full net-shaping of reaction bonded silicon carbide (RBSC) and reaction bonded boron carbide (RBBC). During LPBF, silicon is used as a structural binder instead of traditional sacrificial polymer binders. By combining this with liquid silicon infiltration (LSI) as a densification method, long de-binding times and densification shrinkage are avoided. This leads to a net-shaping, additive manufacturing process for RBSC and RBBC ceramics with high Young's modulus (285 and 308 GPa respectively), flexural strength (220 and 168 MPa) and hardness (2045 and 2242 HV).