Comparison and low-temperature sintering mechanism of “K₂O–Na₂O” and “Li₂O–K₂O–Na₂O” fluxes on the porcelain building tiles

抄録

The “K₂O–Na₂O” binary and “K₂O–Na₂O–Li₂O” ternary flux systems on the densification behaviors of the porcelain building ceramic were analyzed. The results showed that when K₂O and Na₂O content were equivalently replaced by Li₂O content, the sintering temperature of “K₂O–Na₂O–Li₂O” flux samples was reduced to 1090–1130 °C, which is lower than that of “K₂O–Na₂O” binary flux sample (1130–1160 °C). The corresponding sintering temperature range of the ternary flux sample is widened from 30 to 40 °C, and thus the bending strength of the ternary flux sample is increased by 3.5 %. energy spectrometer system and “K₂O–Na₂O–Li₂O” ternary frit simulation results indicate ternary flux sample has more Al₂O₃ and SiO₂ content in glass phase than those of the binary flux sample, however, the alkaline oxide contents are higher than those of ternary flux sample. For binary flux samples, “K₂O–Na₂O” fluxes melt themselves due to low melting point and thus suddenly appear a large amount of the liquid phase and have no time to dissolve Al₂O₃ and SiO₂ contents, resulting in low glassy viscosity of the sample. However, when Li₂O content equivalently replace K₂O and Na₂O contents for the ternary flux sample, they would appear high glassy viscosity steeply, due to the formation of low eutectic mixture melted with high Al₂O₃ and SiO₂ contents. Combined with X-ray powder diffraction patterns and scanning electron microscope images, the ternary flux samples have more crystallite phase, smaller porosity and pore size than those of binary flux samples. Therefore, the properties of the ternary flux samples are superior to those of binary flux samples.