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

• Published in: Journal of the Ceramic Society of Japan 2020/10/01, Vol.128(10), pp.821-831
• Main Authors: DONG, Weixia, BAO, Qifu, ZHOU, Jianer, ZHAO, Tiangui, LIU, Kun, LI, Shizhuo, LIU, Siyu, MA, Kexin
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Bend strength; Crystallites; Densification; Diffraction patterns; Equivalence; Fluxes; Frit; Liquid phases; Lithium oxides; Low temperature; Low-temperature sintering mechanism; Melting points; Porcelain; Porcelain building ceramic tile; Pore size; Porosity; Potassium oxides; Silicon dioxide; Sintering; Sintering (powder metallurgy); Viscosity; X ray powder diffraction; “K2O–Na2O–Li2O” ternary flux; “K2O–Na2O” binary flux
• ISSN: 1882-0743; 1348-6535
• DOI: 10.2109/jcersj2.19235

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.