Glass polishing, cerium oxide

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

Walnut (Juglans regia) shell powder abrasive, gentle detergents Sodium borate decahydrate abrasive, gentle soaps Sodium borate decahydrate abrasive, glass polishing Cerium oxide... 

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 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. 

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. 

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

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. 

The demand for the rare earth metals increased over the last two decades of the 20th century, and the demand for cerium oxides in motor vehicle catalytic converters (see equations 26.39 and 26.40) has been a major contributing factor. In 2001, the major use (34% of the total consumption) for rare earth metals in the US was in glass polishing and ceramics. Petroleum catalysts and catalytic converters... 

Cerium oxide is of major importance in the glass industry because of its ability to polish glass, thanks to its natural hardness and to the chemical reaction [24, 25] that takes place at the interface between the glass silica substrate and the cerium oxide particles. This reaction occurs in water and involves the creation of a silicate stratum which makes the glass surface more fragile and less resistant to mechanical erosion and physical modifications. 

Kelsall, A., 1998. Cerium oxide as a mute to acid free polishing. Glass Technol. 39, 6—9. 

Figure 79. Glass surfaces after additional polishing with cerium oxide of grain size 2 pm, DIG.

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