Cement / glass raw materials, equipment, principle, composition, characteristics, uses and types
Ceramic composition used in high melting ceramics is used by manufacturers and is hardly used to make individual ceramic restorations. The material contains 75% to 85% feldspar, 12% to 22% quartz and 4% kaolin. Feldspar forms glass phases, and quartz remains suspended in the form of quartz after sintering. Quartz (SiO2) is used as an intensifier in ceramics. At normal sintering temperature, it has no structural change and plays a role in stabilizing the bulk (mass) at high temperatures.
This is a useful feature because it prevents edges from becoming rounded, loss of tooth shape, and disappearance of surface imprinting, which is conducive to a vivid appearance. Kaolin hydrated aluminum silicate (Al2O3 2SiO2 2H2O), plays the role of adhesive to improve the forming ability of non sintered ceramic. Because of its opacity, the content is minimal. Although many repair ceramics contain free crystalline phases of quartz, they should be described as glass; rather, high melting ceramics can be called feldspathic glass". In the production of medium and low melting ceramics, the manufacturers mix various ingredients to melt them and then quench them in water. Quenching causes internal stresses, causing large cracks and fractures throughout the glass. This process is called the heating of glass material, and the product is called glass material. The brittle structure thus formed can easily be ground into powder for use by the porcelain artist. During the pre melting of ceramics, thermochemical reactions occur between the components, and the shrinkage associated with this reaction occurs. In subsequent chamber sintering, powders are fused together to form restorations. The melting temperature depends on the composition of the glass and must be carefully controlled to minimize thermoplastic flow. Potash (potash) and sodium (soda) is a carbonate or natural minerals (such as feldspar) to be introduced in the form of.
A mixture of feldspar, potassium aluminum silicate (K2O, Al2O3, 6SiO2) and albite (Na2O, Al2O3, 6SiO2) used in dental ceramics. Natural feldspar is not pure, and the proportions of K2O and Na2O vary. At about 1250 to 1500 degrees C (2280~2370 degrees F), feldspar melts into glass with a free crystalline silicon phase. In the feldspar Na2O can reduce the melting temperature, and potassium can increase the glass melt viscosity, reduce the plastic flow during sintering heat (pyroplastic flow).
