Albite is generally suitable for low temperature ceramics:
1. Before firing, feldspar, like quartz, is a non-plastic raw material, which can shorten the drying time of the green body and reduce drying shrinkage and deformation.
2. Feldspar is the main flux raw material in the blank glaze, such as feldspar porcelain, feldspar accounts for about 25% in the blank body and about 50% in the glaze, and its main function is to reduce the firing temperature of the blank glaze.
3. Feldspar is melted into feldspar glass at high temperature, filled between the particles of the green body, and can dissolve other minerals, such as kaolinite, quartz, etc., to make the green body compact, which helps to improve the mechanical strength and electrical properties of the product and translucency.
4. Compared with potassium feldspar, albite feldspar has a greater effect on reducing the firing temperature of the blank glaze, and at the same time can improve the translucency of the product, but the firing temperature range is not as wide as that of potassium feldspar.
5. Requirements for feldspar in ceramic production:
6. The content of K2O and Na2O should be as high as possible, and the content of colored oxides Fe2O3 and TiO2 should be as low as possible;
7. The content of SiO2 should be in the range of 63%-68%, and the content of Ali2O3 should be in the range of 17%-23%;
8. The content of CaO in feldspar should not be too high. If the content is too high, it is easy to reduce the sintering temperature when it is used in blank, and it will affect the fluidity of glaze when it is used in glaze.
Albite Chemical Formula
The chemical molecular formula of albite is: Na2O·Al2O3·6SiO2. Its theoretical chemical composition is Na2O: 11.8%; Al2O3: 19.4%; SiO2: 68.8%. It is 2.61-2.64 g/cm3, and its melting point is about 1100°C. 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. During the heating process, albite has a theoretical melting point of 1100°C. The melting point of natural albite ore varies with the chemical composition.
Albite Formation Conditions
Albite, a common feldspar mineral, is sodium aluminosilicate (NaAlSi3O8). Most common in pegmatites and felsic igneous rocks such as granite, also in low-grade metamorphic rocks, and in some sedimentary rocks as authigenic albite. Albite usually forms brittle glassy crystals of various colors. It can be used to make glass and ceramics, but its main significance is that it is a rock-forming mineral.
Albite is a sodium terminal mineral of plagioclase solid solution series and alkaline feldspar series. It has a tripod-like structure, and silicon and aluminum are tetrahedrally coordinated to form larger vacancies (ie, lattice positions), which are mainly occupied by cationic sodium. Although all silicon and aluminum atoms occupy tetrahedral positions in this structure, the specifics of their positions vary. The distribution of silicon and aluminum atoms is highly ordered at low temperature, but at a high temperature of about 1100°C, the distribution of atoms is much more disordered.