Soda Feldspar is a common sodium-containing aluminosilicate rock-forming mineral, which is generally used in the manufacture of ceramic green body ingredients and glazes. Before the firing of the ceramic body ingredients, sodyum feldspat can play the role of lean material, reduce the drying shrinkage and deformation of the billet, improve the drying performance and shorten the drying time. Albite feldspar can be used as a flux to fill the green body during firing, making the green body compact and reducing voids, and can also improve the light transmittance of the green body.
The chemical formula of Na feldspat is: Na2O·Al2O3·6SiO2. Its theoretical chemical composition is Na2O: 11.8%; Al2O3: 19.4%; SiO2: 68.8%. The content of soda feldspar in Anyang Lishi Industrial is:
Al2O3: 19-22%
SiO2: 65% min
Fe2O3: 0.1%±0.05
Na2O: 11%±0.5
CaO: 0.6% max
It is difficult for the albite mineral in nature to reach its theoretical value. The closer the chemical composition of feldspar is to its theoretical value, the purer the feldspar and the better its quality. The Na2O content of common sodium feldspar in the market is 9.5%~10% (±0.5), and albite of Anyang Lishi Industrial Na2O content is 1%~2% higher than ordinary Na feldspar, which belongs to high-quality Na feldspar.
Traditional ceramic billets, they are mostly composed of mineral raw materials with high refractoriness (such as clay minerals, quartz, etc.), and the reason why they can be fired into porcelain mainly depends on the flux of raw materials with low melting points. The melting point of sodium feldspar is about 1100°C, which is one of the natural raw materials with the lowest melting point. In addition to the low melting point, the viscosity of the glass phase containing Na2O is also low, which can accelerate the sintering reaction and the migration and diffusion of components. In addition, the raw material of Na2O mineral in soda feldspar is barren, which can reduce the drying shrinkage and shorten the drying time. All these factors make sodyum feldspat the advantages of reducing the sintering temperature and speeding up the sintering speed.
The transparency of the ceramic body is mainly related to the amount of glass phase in the body, the more glass phase, the more transparent; secondly, it is related to the refractive index difference between the crystalline phase and the glass phase in the body (the smaller the difference, the more transparent). The Na2O composition in soda feldspar belongs to the low melting point component in the composition of the ceramic body, the more Na2O content, the more glass phase is generated, so it is beneficial to improve the transparency of the green body. In the production of polished tiles with high-end artistic effects, high-quality albite can improve transparency and make the products more artistic.