Study on dual binders for fabricating SiC particulate preforms using selective laser sintering

The SiC preforms were successfully produced by selective laser sintering and thermal treatment for fabricating the near-net-shape composites with high SiC volume fraction. The effects of dual binders on the forming accuracy, microstructure and mechanical properties of SiC preforms were investigated. Results show that the SiC preforms with forming accuracy of 98.89% were fabricated by using the dual binders of nylon 6 + NH4H2PO4, which fits the requirement of subsequent near-net-shape manufacturing compared with using single binder of nylon 6 after thermal treatment, the tensile and bend strength were significantly improved by using the dual binders of nylon 6 + NH4H2PO4, which are strong enough to support the external load during infiltration. The bonding among SiC particulates primarily depends on nylon 6 after laser sintering, but after the decomposing of nylon 6, the reaction product of SiP2O7 phases can provide effective bonding for maintaining the forming accuracy and supporting mechanical properties of SiC preforms.