| 简介 |
PROBLEM TO BE SOLVED : To provide a cerium oxide-based polishing agent substantially free of fluorine that can polish a glass substrate used for a hard disk substrate at high polishing speed, while achieving the reduction of surface roughness of glass substrate and the suppression of the occurrence of polishing flaws, and to provide a method for manufacturing a hard disk substrate made of glass.
SOLUTION : There are provided a cerium oxide-based polishing agent for a hard disk substrate made of glass that satisfies the following requirements (1) to (5); and a method for manufacturing the hard disk substrate made of glass using the polishing agent. (1) The cerium oxide-based polishing agent has the total amount of rare earth oxides (TREO) of 95 mass% or more, and the amount of cerium oxide of 99 mass% or more based on the TREO. (2) The cerium oxide-based polishing agent contains fluorine of 0.05 mass% or less. (3) The cerium oxide has the crystallite diameter of 700 to 1000 Å calculated from powder X-ray diffraction. (4) The cerium oxide has the average particle diameter (D50) of 0.4 to 0.8 μm. and (5) The hard disk substrate made of glass has the Vickers hardness of 570 Hv or more.
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