Quantitative analysis and comparison on densification kinetics and grain growth mechanisms using reactively and directly densified TiB2-SiC-hBN ceramics.

Compared to samples sintered from directly mixed powders, reactive sintering enables the production of denser ceramic materials with finer grains at even lower temperatures. However, there is a lack of quantitative comparisons between the two sintering approaches in terms of densification mechanisms and grain growth kinetics. In this work, taking two types of TiB 2 -SiC- h BN ceramics sintered from raw powders containing TiB 2 , SiC and h BN (TSB-M) and TiN, Si and B 4 C (TSB-R) as model materials, above mechanisms were quantitatively investigated using spark plasma sintering. Effects of dwell temperature and sintering pressure on the microstructure evolutions, densification kinetics as well as grain growth of TSB-R and TSB-M were thoroughly examined. The densification mechanisms for both samples under different conditions were revealed by calculating the effective stress exponent and apparent activation energy. According to regression coefficients for different grain growth exponents, the dominated growth mechanisms for SiC and TiB 2 grains were also explored. [ABSTRACT FROM AUTHOR]