Densification process of TaC/TaB2 composite in spark plasma sintering

A TaC composite with ∼11 wt% in situ TaB2 was fabricated by spark plasma sintering at 1600–1900 °C. The densification process was studied by analysis of the densifying shrinkage of the powder compacts. Three distinct stages for densification were determined. The starting powder mixture of TaC, B4C and Ta completed reaction to form the desired TaC and TaB2 at temperature <1583 °C. At around ∼1750 °C, the TaC/TaB2 material significantly improved relative density to ∼95% with rapid grain growth. The final densification took place very rapidly at 1900 °C by releasing a high pressure vapor.

Research highlights
► A TaC composite with ∼11 wt% in situ TaB2 was prepared by spark plasma sintering at 1600–1900 °C.
► The densification process was investigated.
► The difficulties in eliminating the last residual pores was found to be associated with an evaporting mechanism.