Influence of binder content and the ratio of plasticizer to binder on tape casting and sintering performance of CaO–B2O3–SiO2–Al2O3 glass/Al2O3 ceramics

The present research was carried out to determine the optimum amount of polyvinyl butyral binder (PVB) in CaO-B2O3-SiO2-Al2O3 (CABS) glass/Al2O3 ceramics casting slurries. The mechanism of the binder on the powder was analyzed in detail, and the optimum amount of binder addition was determined by analyzing the rheological properties of the slurries, the densities and the mechanical properties of the green tapes. Moreover, the laminated shrinkage and the roughness of green casting tapes were analyzed to further verify the optimum binder content. Under the condition of the experimental binder content, we studied the effects of different ratios of dibutyl phthalate plasticizer (DBP) to binder on green tapes and sintered bodies to determine the moderate plasticizer content. We illustrated the plasticizing mechanism of dibutyl phthalate (DBP) in casting slurry. Then, the rigidity and the breaking elongation of the green tapes with different ratio values were tested to preliminarily determine the best ratio of plasticizer to binder. Next, in the light of the TG and DSC curves of the green tape, we defined the details of sintering. Finally, according to the microstructure, dielectric loss and dielectric constant of the sintered bodies, the sample with 9.5 wt% PVB addition and the ratio value = 0.5 showed the best performance.