Effects of Cr3C2 addition on the corrosion behavior of Ti(C, N)-based cermets

The Ti(C, N)-based cermets with different Cr3C2 addition were prepared and the effects of Cr3C2 addition on the microstructure and properties of cermets were discussed. The corrosion behavior of the cermets with different Cr3C2 addition was investigated emphatically in 2 mol/L HNO3 solution. The results indicate that there is no obvious effect of Cr3C2 addition on the densification of the cermets, and all cermets are almost fully densified during sintering. The thickness of rim phase is reduced and the core size is increased remarkably in the cermets with 1 wt.% and 3 wt.% Cr3C2 addition; the grains are refined significantly in the cermets with the increase of Cr3C2 addition to 5 wt.%. The hardness and transverse rapture strength of the cermets are improved with Cr3C2 added properly. In HNO3 solution, the corrosion resistance of cermets is improved remarkably by Cr3C2 addition. The corrosion of binder phase is predominant in the cermets in which the Ni binder phase without Cr has lower corrosion resistance than the rim phase; whereas the corrosion resistance of binder phase with high Cr content is better compared to the rim phase, so that the degradation of rim phase is predominant and a reticulate binder phase forms. With the increase of Cr3C2 addition, the Mo content in rim increases, and it is bad for the corrosion resistance of rim phase. Additionally, the inner rim phase has lower corrosion resistance than the outer rim phase owing to the higher Mo content.

► Corrosion rates of cermets decreased with Cr3C2 addition.
► Corrosion behavior of cermets with Cr3C2 addition was classified to CCB, CCD and CCR.
► Corrosion resistance of binder was improved by Cr3C2 to form a reticulate phase.
► Mo content in rim phase increased with Cr3C2 addition.
► Corrosion resistance of rim was worsened by Cr3C2 due to the increase of Mo in rim.