Physical Properties and Corrosion Behavior of Mo-YSZ Cermets in Molten Iron: Effects of Composition and Particle Size

Mo-ZrO₂ cermets are considered promising protective materials in metallurgical applications. The Mo-YSZ (3 mol pct Y₂O₃-stabilized ZrO₂) cermets were prepared by powder sintering method. The study examined how YSZ content and initial particle size affect the properties and the corrosion resistance of cermets in molten iron. Among them, the cermets fabricated using finer particle size powders exhibited superior mechanical properties and excellent corrosion resistance. For instance, U-Mo-40YSZ (a cermet with 40 vol. pct YSZ, prepared using ultrafine powders) showed 60.69 pct higher bending strength and 34.18 pct higher Vickers hardness than M-Mo-40YSZ (a cermet with 40 vol. pct YSZ, prepared using micron-sized powders). During corrosion, Mo was corroded to form a Mo–Fe solid solution, which was then melted into the molten iron at high temperatures. The corrosion kinetics of the cermets followed a parabolic law, indicating that the existence of YSZ effectively decelerated the corrosion rate. The increase in YSZ content and the reduction of initial particle size both contribute to decreasing the total corrosion depth. After corrosion for 2 h, the total corrosion depth of U-Mo-60YSZ was 46.26 pct lower than U-Mo-40YSZ and 6.43 pct lower than M-Mo-60YSZ. The residual YSZ underwent the secondary sintering during corrosion, forming a highly dense skeleton layer. This effectively restrained the penetration of molten iron into the cermet, thereby enhancing the corrosion resistance of the cermet.