The macro morphology of the preform is shown in figure (a). After sintering, ztap is fully wrapped by HCCI to form a honeycomb structure. The diameter of the middle through-hole is 20 mm, which can increase the contact area between molten iron and the preform during the casting process, and improve the bonding strength between the metal matrix formed by the through-hole filling and the preform.
After grinding, the ztap / HCCI composite has no crack and shrinkage cavity. The macro morphology is shown in Fig. (b). The composite surface can be divided into composite zone and columnar zone. In the composite zone, ztap is evenly distributed on the surface of HCCI matrix. Ceramic particles are isolated from each other and separated by HCCI matrix, and no agglomeration occurs, as shown in Fig. (c). In HCCI casting process, the honeycomb preform holes are injected and filled to form a columnar zone. There are no dispersed ceramic particles in the columnar region, which indicates that the sintered preform can effectively resist the high temperature erosion of molten iron in the casting process.