GB1142185A - Rare earth chlorides in a glass polishing composition - Google Patents

Abstract

1,142,185. Polishing glass. LIBBY-OWENS-FORD GLASS CO. 4 April, 1967, No. 15261/67. Heading B3D. [Also in Division C4] A glass surface is finished by rubbing a water slurry of cerium oxide or iron oxide over the surface with a soft tool, a rare earth chloride being added to the slurry prior to the rubbing. A polishing composition comprises 100 parts (by weight) of water, 0À5-20 parts of cerium oxide and 0À225-2À25 parts of cerous chloride. The cerous chloride may be added in a mixture of rare earth chlorides containing approximately 45% cerous chloride, the composition then comprising 100 parts (by weight) of water, 0À5-20 parts of cerium oxide and 0À5-5 parts of the mixture of rare earth chlorides. Preferably 1-6 parts of cerium oxide and 0À5-2 parts of the mixture of chlorides are used. The mixture of chlorides may be obtained from monazite sand and have the composition, calculated as the hexahydrates:- Per cent by weight Cerous chloride 45À4 Lanthanum chloride 23À8 Neodymium chloride 16À6 Praseodymium chloride 4À8 Samarium chloride 2À9 Gadolinium chloride 2À1 Ytrrium chloride 0À3 There may be traces of thulium chloride, holmium chloride and dysprosium chlorides. Plate glass blanks 13 are embedded in a layer of plaster 14 on tables 11 moved under rotating grinding tools 15 and rotating polishing runners 16 each including felt covered polishing tools 17. A sand-water mixture is fed through conduits 18 in the shafts 19 of the grinding tools 15, and is removed from the glass surface by squeegees 21. Polishing composition is supplied by pipes 22.