For h-BN/mullite composite ceramics, after being sputtered by Xe ion flow, the various surface morphologies along different directions are shown in Fig. 9, indicating different sputtering erosion characteristics. On the sputtered surfaces parallel to the h-BN layers (Fig. 9(a) and (b)), there are several erosion craters generated by Xe ion bombardment. In addition, laminated grains and layered pieces can be obviously observed by removing the surface materials. In contrast, on the sputtered surfaces perpendicular to the h-BN layers, rough and uneven surfaces are obtained after sputtering, and laminated h-BN grains perpendicular to the surface are exposed (Fig. 9(c) and (d)) [42].