Mold flux serves the crucial metallurgical function of absorbing inclusions, directly impacting the smoothness of the casting process as well as the cast slab quality. In this study, the dissolution behavior and mechanism of TiO 2 and TiN inclusions in molten CaO–SiO 2– B 2 O 3 -based fluorine-free mold flux were explored by in situ single hot thermocouple technology combined with X-ray photoelectron spectroscopy. The results showed that TiO 2 inclusions are effectively dissolved by the molten slag within 76 s, during which the original octahedral [TiO 6 ] 8− structures are destroyed and convert to the networker tetrahedral [TiO 4 ] 4− structures. However, the dissolution rate is much lower for TiN inclusions than for TiO 2 inclusions. This can be attributed to the fact that the TiN particles need to be oxidized and then dissolved in the molten slag to form tetrahedral [TiO 4 ] 4− and octahedral [TiO 6 ] 8− structures during the TiN inclusion dissolution process, which is accompanied by the generation of a large amount of N 2 gas. Moreover, CaTiO 3 crystals tend to nucleate and grow on bubble surfaces with sufficient octahedral [TiO 6 ] 8− structures and Ca 2+ ions, eventually resulting in the molten slag being in a solid–liquid mixed state.
This present work aimed to attain a high-performance tape for LTCC application by using butyl benzyl phthalate as plasticizer in tape casting slurry of CaO–SiO 2 –B 2 O 3 glass–ceramics. The plasticizing mechanism of butyl benzyl phthalate in suspensions was demonstrated in depth. Dried droplets of binder were prepared to preliminarily judge the compatibility of binder and plasticizer, and the optimal additive amount was determined by rheological characteristic. In addition, a series of qualitative and quantitative methods were carried out to assess the tensile strength and elongation of green tapes, microwave properties and densification of sintered bodies. The experimental results revealed that when the addition of BBP was up to 45 wt%, tape casting slurries had the optimal fluidity and green tapes obtained the excellent performance with density at 1.65 g/cm 3 , tensile strength at 1.43 MPa and elongation at 13.4%. Meanwhile, sintered bodies fired at 850 °C achieved the highest density at 2.42 g/cm 3 with ε r = 5.94 and tanδ = 10 × 10 −4 at 10 GHz.
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