Improving dispersibility of hafnium diboride in aqueous media using polyacrylic acid and ammonium citrate

It has been well accepted that polyacrylic acid (PAA) is an effective dispersant for metal diborides (such as ZrB₂) in aqueous media. However, when dispersing HfB₂ powder, the dispersing effect is reduced significantly. In this work, a second dispersant, ammonium citrate, was used to resolve this problem. It was found that a PAA-ammonium citrate binary dispersant system could effectively enhance the zeta potential, increase the PAA adsorption content, and improve the stability of HfB₂. The apparent viscosities of the suspensions were also investigated. Results showed that the PAA-ammonium citrate binary dispersant system was effective for improving the dispersion of HfB₂ particles in aqueous media.