Recently, an experiment shows that and h-BN ceramic can evenbe completely corroded and consumed in molten steel, as reportedby Marple and Sinclair [60,61]. Thus, it is necessary to add refrac-tory components as inhibitor to form the protective barrier againstcorrosion. Experimental results for corrosion morphologies of com-posite with different ZrO2content after corroded by molten steelat 1600◦C for 40 min are investigated systematically, as shown inFig. 13 [63]. The remarkable result is that no dense transition layercan be detected in the composite incorporation with 10 vol.% ZrO2.The ZrO2skeleton would have a potential problem of collapsing dueto loss of the matrix structure since ZrO2particles are not enoughto overlap together. When ZrO2content is more than 20 vol%, thedense transition layer begins to form, and its thickness increaseswith increasing ZrO2content [63].Without protective refractories addition, the h-BN and non-oxide are easily corroded by molten steel. ZrO2are effectiveinhibitors for weakening corrosion process, which can inhibit theformation of protective layer between the bulk composite andmolten steel. The corrosion rate is decelerated by the addition ofZrO2. Therefore, the addition of ZrO2is beneficial to the decreaseof corrosion rate, and improves the corrosion resistance by retard-ing the infiltration of dissolved oxygen into bulk composite. As aresult, h-BN-ZrO2-SiC composite ceramics have been considered aspromising materials in metallurgical industry, especially directlycontacting with molten steel as containment materials for contin-uous casting of steel.The corrosion mechanisms of h-BN matrix composite ceram-ics in molten steel are mainly proposed by slight dissolution andchemical reaction with dissolved oxygen. Recently, several physicaland empirical models have been developed for corrosion processesof ceramic matrix composites. A general modeling can be madeby assuming the simple linear and parabolic terms for corrosionprocess against molten steel. Chen et al. calculated the values oflinear and parabolic rate constants of h-BN-ZrO2-SiC composites inmolten steel at 1600◦C [63]. Kumar et al. further extend this ideaby accounting for the corrosion depth in the radial direction withusing the multiphase METSIM model in combination with FactSageto investigate interaction between molten steel and compositesin N2atmosphere [62]. The model prediction trends further con-firm that residual corrosion layer as inhibitor plays an active rolein the improvement of corrosion resistance by obstructing the fur-ther infiltration of molten steel. The components would come incontact with steel only through the formed pores, which slowed itsdissolution and corrosion process.