Ceramic raw materials
close The raw material of pottery is clay. The raw material of porcelain is kaolin. Here's a brief introduction: whiteness is one of the main parameters of kaolin's technological performance, and kaolin with high purity is white. The whiteness of kaolin is divided into natural whiteness and calcined whiteness. For ceramic raw materials, the whiteness after calcination is more important. The higher the whiteness, the better the quality. The ceramic process stipulates that drying at 105 ℃ is the grading standard of natural whiteness, and calcining at 1300 ℃ is the grading standard of calcined whiteness. Whiteness can be measured with a whiteness meter. The whiteness meter measures 3800-7000? A device for the reflectivity of wavelength light. In the whiteness meter, compare the reflectivity of the sample to be measured with that of the standard sample (such as BaSO4, MgO, etc.), that is, the whiteness value (for example, the whiteness of 90 means 90% of the reflectance of the standard sample). Kaolin is mainly composed of small lamellar, tubular, laminated and other kaolinite cluster minerals (kaolinite, dickite, perlite, halloysite, etc.) with less than 2 microns. The ideal chemical formula is AL2O3-2SiO2-2H2O. Its main mineral composition is kaolinite and polyhydrate kaolinite. In addition to kaolinite cluster minerals, there are also montmorillonite, illite, pyrophyllite Quartz is associated with other minerals such as feldspar. The chemical composition of kaolin contains a large amount of AL2O3, SiO2, a small amount of Fe2O3, TiO2 and a small amount of K2O, Na2O, CaO and MgO. China is the first country in the world to discover and use kaolin. The carved white pottery, which appeared in the Shang Dynasty 3000 years ago, is made of kaolin. The porcelain produced in Jingdezhen, Jiangxi, is famous both at home and abroad, and has always been known as "as white as jade, as bright as a mirror, as thin as paper, and as loud as sound". Kaolin, the scientific name of kaolin now commonly used in the world, originates from the Gaoling Mountain near the Gaoling Village in the eastern suburb of Jingdezhen. The composition of pure porcelain clay is: SiO2 46.51%, Al2O3 39.54%,H2O 13.95%, The melting degree is 1780 ℃. Pottery clay refers to the clay with good plasticity, which contains iron and has yellow brown, gray white, red purple and other colors. The mineral composition is mainly montmorillonite and kaolin. Pottery clay is mainly used for firing exterior walls, floor tiles, pottery tools, etc. The mineral composition of clay is complex, mainly composed of kaolinite, hydromica, montmorillonite, quartz and feldspar. The particle size is inconsistent, often containing sand, silt and clay. It has water absorption and adsorption, and has plasticity after adding water. The color is impure, often with yellow, gray and other colors, so it is only used for pottery manufacturing. Sampling analysis of clay: containing 65.18-71.86% silica, 15.02-17.99% alumina, 3.27-6.61% ferric oxide, 0.75-1.68% calcium oxide, 0.89-2.07% magnesium oxide, and 4.19-6.20% loss on ignition.