Pressure-controlled synergy between dehydrogenation and densification in TiH2 sintering

Abstract

Titanium hydride (TiH₂) ceramics have become key high-performance hydrogen storage materials. However, the sintering of TiH₂ faces significant challenges due to the low temperature of dehydrogenation reaction (300–800 °C). In this study, high-pressure spark plasma sintering (HPSPS) technique was employed to successfully realize low-temperature high-density preparation by suppressing dehydrogenation and regulating densification kinetics under a high pressure (200 MPa). Under the optimized conditions (750 °C, 200 MPa, and 10 min), a fully dense single face-centered cubic (FCC) δ-Ti(H) phase bulk material was fabricated. The initial dehydrogenation temperature of samples fabricated by high-pressure spark plasma sintering (HPSPS) was higher than the dehydrogenation temperature of powder. Mechanistic analyses showed that high pressure inhibited hydrogen escape by compressing pores while promoting particle plastic flow and interfacial bonding. Increasing holding time from 5 to 10 min enhanced diffusion-dominated densification but exacerbated dehydrogenation-induced porosity under low-pressure conditions. The study shows that high pressure compaction can alleviate the contradiction between traditional high temperature densification and low temperature decomposition of TiH₂, and offers a new strategy for the efficient densification of materials for low temperature decomposition.