Tribocorrosion behaviors of TiC-based cermets with CoCrNi multi-principal element alloy binders

TiC-based cermets are lightweight substitutes to the conventional WC-Co composites in ocean drilling applications. However, the tribocorrosion behaviors of these cermets remain little understood, raising additional concerns on their service durability. In this work, the role of metallic binder composition on the tribocorrosion behaviors of TiC-based cermets was studied. Specifically, the TiC-CoCrNi and TiC-Ni cermet samples were fabricated using the spark plasma sintering (SPS) method, and their corrosion and tribocorrosion properties were assessed in 3.5 wt% NaCl solutions. Results showed that the TiC-CoCrNi exhibited declined corrosion current density by ∼12 %, benefiting from the reduction of galvanic corrosion, the decreased number of interfaces and the favorable formation of Cr2O3. In addition, the TiC-CoCrNi revealed decreased volumetric losses by ∼30 % under the open circuit potential (OCP) condition. It was found that the comparatively intact CoCrNi binders in the corrosive media guaranteed the tolerance of TiC skeleton to the sliding-induced plastic deformation and facilitated the formation of tribolayers that consisted of detached TiC and transferred Al2O3, both of which contributed to the maintenance of robust contact surfaces. Hence, this work demonstrates the possibility of employing multi-principal element alloy binders to strengthen the tribocorrosion properties of TiC-based cermets through the build of stable tribolayers. •Tribocorrosion mechanism of TiC-based cermets with CoCrNi binders was studied.•CoCrNi binders alleviated galvanic corrosion and guaranteed surface deformability.•Protective tribolayers containing wear debris and transferred materials were noted.