METHOD OF PREPARING POLISHING MATERIAL ON THE BASIS OF RARE-EARTH ELEMENT OXIDES Russian patent published in 1995 - IPC

FIELD: polishing powders. SUBSTANCE: spent suspension of polirit is dissolved in nitric acid. Solution is filtered, treated with hydrogen peroxide, diluted with water up to the rare-earth element total content 0.12-0.25 M/l and nitric acid - 0.6-2.0 M/l, cooled up to 20 C, and saturated solution of oxalic acid is added. Mole ratio of rare-earth elements : РЗЭ : H₂C₂O₄ = 1: 2. Precipitate is filtered and subjected for stage thermal treatment at 120-150, 280-330, 450-500 and 950-1030 C. Product is kept at 750-800 C for at least 2 h. Material does not form cakes. Polishing capability is 58 mg/30 min. Yield of polishing powder is 85%. EFFECT: improved method of polishing material preparing. 1 tbl