Effect of sintering aids on the structure and corrosion behaviour of spark plasma sintering-assisted TiB2-based coatings

Abstract

The present study explores the effects of titanium (Ti) and aluminum nitride (AlN) as sintering aids on the microstructure and corrosion behaviour of TiB2-based coatings deposited on the Ti substrate by spark plasma sintering at 1200 °C. A series of compositions comprising of pure TiB2, TiB2 + 2.5 wt% Ti, and TiB2 + 2.5 wt% Ti + 5 wt% AlN were successfully deposited and investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that Ti and AlN promote in-situ formation of secondary phases like TiB, TiN, and Al5BO9, enhancing densification and interfacial bonding for the TiB2 + Ti + AlN coatings. Electrochemical tests in a simulated PEMFC environment (0.5 M H2SO4 + 2 ppm HF) showed that the TiB2 + Ti + AlN coating exhibited the lowest corrosion current density (∼1.6 × 10−5 A/cm2) and noblest corrosion potential (0.20 V vs Ag/AgCl), attributed to its compact microstructure that minimizes electrolyte ingress and TiN enrichment on the surface. In contrast, pure TiB2 and TiB2 + Ti coatings displayed higher dissolution rates due to porosity and galvanic effects. It has been shown that the combined use of Ti and AlN enables low-temperature densification of TiB2-based coatings while significantly enhancing their corrosion performance in aggressive acidic conditions, making them highly suitable for bipolar plate applications in PEMFCs. © 2026 Elsevier B.V.