Effect of Ni content on the corrosion behavior of Mo₂NiB₂–Ni cermet in H₂SO₄ solution

To promote the utilization of Mo₂NiB₂–Ni cermet under sulfuric acid drew corrosion conditions, it is essential to elucidate the resistance mechanism of these cermets to sulfuric acid corrosion. In this study, the corrosion behavior of Mo₂NiB₂–Ni cermets with different Ni content in 90 wt % H₂SO₄ solution at 110 °C was investigated, and the corrosion resistance mechanism was analyzed. The results reveal that the corrosion weight losses and corrosion rates of the cermets decreased with increasing Ni content. Mo₂NiB₂–Ni cermets with higher Ni contents exhibited improved corrosion resistance. This improvement can be attributed to the generation of a considerable amount of NiSO₄ corrosion products from the Ni binder phase corroded by H₂SO₄, which led to the subsequent formation of a large-scale, flat, and dense corrosion products layer with a certain thickness. This effectively prevented further erosion of the inner matrix and improved the corrosion resistance of the cermet. Additionally, the electrochemical results indicate that the corrosion product layer hindered the passage of electric charges through the layer, which inhibited the corrosion reaction.