Cerium polishing

C cerium concentrate glass polishing, glass decolorizing dominant element... 

The cerium concentrate derived from bastnasite is an excellent polish base, and the oxide derived direcdy from the natural ratio rare-earth chloride, as long as the cerium oxide content is near or above 50 wt %, provides an adequate glass poHsh. The polishing activity of the latter is better than the Ce02 Ln0 ratio suggests. Materials prepared prior to any Ln purification steps are sources for the lowest cost poHshes available used to treat TV face plates, mirrors, and the like. For precision optical polishing the higher purity materials are preferred. 

Some rare earth compounds are used in glassmaking. Cerium is the most abundant, and its compounds are used to polish glass. Lanthanum compounds are used in making glass lenses, and praseodymium compounds color glass green. 

The compound cerium oxide (either Ce Oj or CeO ) is used to coat the inside of ovens because it was discovered that food cannot stick to oven walls that are coated with cerium oxide. Cerium compounds are used as electrodes in high-intensity lamps and film projectors used by the motion picture industry. Cerium is also used in the manufacturing and polishing of high-refraction lenses for cameras and telescopes and in the manufacture of incandescent lantern mantles. It additionally acts as a chemical reagent, a misch metal, and a chemical catalyst. Cerium halides are an important component of the textile and photographic industries, as an additive to other metals, and in automobile catalytic converters. Cerium is also used as an alloy to make special steel for jet engines, solid-state instruments, and rocket propellants. 

Period of Wide Technical Application. In the time between 1930 and 1940 work was done on various applications for the rare earth elements. Particularly successful was the production of sunglasses ("Neophan"), polishing media from rare earth oxides to replace iron oxide, decolorization of glass using cerium oxide, pure cerivim oxide as opacifier in ceramic glazes, use of cerium... 

The free world market for cerium-oxide based polishing compounds is not large—approximately 4400 metric tons per year—, and we do not see a substantial growth potential despite the 11% annual growth in sales of spectacle lenses. The reason is twofold first, faster more efficient polishing compounds are available which can be used in slurry concentrations one-half that of a few years ago second, fully half the market for ophthalmic glass lenses has been captured by plastic lenses of CR-39 polymer. Cerium oxide is ineffective in polishing this material specially treated alumina or stannic oxide are used. 

Table I shows our estimate of 1979 cerium-oxide based polishing product consumption.

The estimated end-use pattern for cerium oxide based polishing compounds in the U.S. (1979) is illustrated in Table II. 

TABLE II. ESTIMATED END USE PATTERN IN THE UNITED STATES FOR CERIUM-OXIDE BASED POLISHING COMPOUNDS (1979) a... 

High polishing speeds are essential in todays economy, and the latest equipment employs much higher spindle speeds and pressures than those used just a few years ago. Cerium oxide is ideal under these more modern conditions, A spherical lens that required 8 minutes to polish 15 years ago is now polished in less than one minute, A toric (cylinder) lens that previously took 15 minutes to polish, now requires 4-1/2 minutes. 

Duncan, L, K, "Cerium Oxide for Glass Polishing" Glass Industry, (1970), (7), 387-393,... 

Glass polishes -cerium oxide as [CERIUMAND CERIUM COMPOUNDS] (Vol 5)... 

Cerium 58 Ce Polishing powders, opacifier for porcelain coatings, glass decolouriser and melting accelerator, photographic materials, textiles, arc lamps, ferrous and non-ferrous alloys including high-temperature Mg alloys, automotive catalytic converters, misch metal... 

Cerium oxide is the most efficient polishing agent for most glass compositions [23]. This application consumes a significant portion of the cerium products produced annually. 

Cerium oxide is also used as an abrasive. An abrasive is a powdery material used to grind or polish other materials. Cerium oxide has replaced an older abrasive known as rouge for polishing specialized glass, such as telescope mirrors. 

Cerium is the principal metal in the alloy called misch metal. Misch metal is 50 percent cerium combined with lanthanum, neodymium, and a small amount of iron. Misch metal is used to make the flints for lighters. Cerium is often included in alloys of iron and other metals such as magnesium. A high-temperature alloy of three percent cerium with magnesium is used for jet engines. Some of cerium s compounds—for example, cerium(IV) oxide —are used to polish lenses, mirrors, and televi-... 

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