Influence of dispersant on the microstructure and performance of the hot-pressed B4C-YB4 ceramics

Abstract

The influence of different dispersants on the dispersion of Y₂O₃ sintering aid in B₄C powder and the microstructure and performance of the subsequently hot-pressed ceramics were studied in this paper. The results indicated that ammonium polycarboxylate (APC) could effectively enhance the distribution of Y₂O₃ in B₄C powder, and further improve the distribution homogeneity of the formed second phase YB₄ in the fabricated ceramics. Polyethyleneglycol (PEG) 600 was beneficial to breaking the Y₂O₃ agglomeration in B₄C powder and improving the distribution of YB₄. The remaining PEG 600 in the mixed powder would react with B₄C and Y₂O₃ particles to form the dendritic-structure second phase in the sintering process, which comprised some whisker-like branches and a layer of film. The distribution of YB₄ in the fabricated ceramics was slightly improved by adding sodium citrate (SC) dispersant. Y₂O₃ reacted with B₄C to form the intergranular and intragranular YB₄, and liquid phase was formed in the sintering process, facilitating the rearrangement of B₄C grains and improving the densification. The dispersant APC could improve the homogeneity of YB₄, promoting the densification and strength of the ceramics.