Effects of ZnO as additive on structure and properties of ceramic layer were investigated

and were compared with those of compound pipe with adding 4%SiO2+4%CaF2. The results indicate that the structure of ceramic layer is converted from arranged dendrite into fine equiaxed crystal and the density of ceramic layer as well as compressive strength of compound pipe are improved with ZnO addition. The density of ceramic layer and compressive strength of compound pipe are 4.520 g/cm3 and 406 MPa

respectively

with 6%ZnO addition

which are greatly superior to that of compound pipe with 4%SiO2 +4%CaF2 addition.