Ceramic materials and wares, chemicals
Ceramic materials and wares, chemicals
This category encompasses the various chemical substances manufactured in the production of ceramics.  For purposes of this category, a ceramic is defined as a crystalline or partially crystalline, inorganic, non-metallic, usually opaque substance consisting principally of combinations of inorganic oxides of aluminum, calcium, chromium, iron, magnesium, silicon, titanium, or zirconium which conventionally is formed first by fusion or sintering at very high temperatures, then by cooling, generally resulting in a rigid, brittle monophase or multiphase structure.  (Those ceramics which are produced by heating inorganic glass, thereby changing its physical structure from amorphous to crystalline but not its chemical identity are not included in this definition.)  This category consists of chemical substances other than by-products or impurities which are formed during the production of various ceramics and concurrently incorporated into a ceramic mixture.  Its composition may contain any one or a combination of these substances.  Trace amounts of oxides and other substances may be present.  The following representative elements are principally present as oxides but may also be present as borides, carbides, chlorides, fluorides, nitrides, silicides, or sulfides in multiple oxidation states, or in more complex compounds.:  Aluminum; Barium; Beryllium; Boron; Cadmium; Calcium; Carbon; Cerium; Cesium; Chromium; Cobalt; Copper; Hafnium; Iron;  Lithium; Magnesium; Manganese; Phosphorus; Potassium; Silicon; Sodium; Thorium; Tin; Titanium; Uranium; Yttrium; Zinc; Zirconium