The fracture microstructures of the CS and CSP-CS 0YN specimens sintered at 1400℃ for 2 h and 48 h are presented in Fig. 3. The CS specimen sintered for 2 h displays neck formation between the particles (Fig. 3a), while the CSP-CS specimen sintered for 2 h (Fig. 3c) reveals significant densification compared to the CS specimen. Hence, considering the density of 88.5±0.64% indicated in Fig. 2, the 2-hour CS treatment can still be regarded as an intermediate sintering stage. When the sintering time was increased to 48 h (Fig. 3b and d), the densifications of both specimens were improved.