Method for producing glass substrate for magnetic disk, and magnetic disk
A glass substrate and glass plate technology, which is applied in the manufacture of glass substrates for magnetic disks and in the field of magnetic disks, can solve problems such as instability of silica gel, coalescence, and discrete surface precision on the main plane
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preparation example Construction
[0015] The production method of the present invention is not limited to the above method. For example, brush polishing may be performed on the inner peripheral edge surface instead of forming a protective coating film on the inner peripheral edge surface; as described in JP-A-2006-82138, the grinding of the main plane may be The steps are divided into a rough grinding step and a fine grinding step, between which a forming treatment step (perforating the center of the circular glass plate, chamfering and polishing the edge surface) can be provided; Alternatively a chemical tempering step may be provided after the main plane polishing step. It goes without saying that when manufacturing a glass substrate without a circular hole in the center, it is not necessary to perforate the center of the circular glass plate.
[0016] The grinding of the main plane is usually performed using alumina abrasive grains, or metal oxide abrasive grains, and the abrasive grains include alumina wi...
preparation Embodiment 1-17
[0071] According to the ratio shown in Table 1 (respectively based on CeO 2 , RO and B 2 o 3 Mole %) Weigh cerium oxide (CeO 2 ), RCO 3 (R is Ba or Sr) and boron oxide (B 2 o 3 ), adding a small amount of ethanol, mixing and pulverizing them in an automatic mortar. The mixture is then dried to obtain a material powder (mixture).
[0072] The prepared material powder was placed in a crucible made of platinum containing 10% by mass rhodium with a nozzle, and heated at 1500° C. for 1 hour in an electric furnace using molybdenum silicide as a heating element to make the material powder completely dissolved.
[0073] Then, while the bottom of the nozzle of the crucible was heated in an electric furnace, the melt was dripped and passed through a double roller with a diameter of about 15 cm and rotating at a speed of 300 rpm, so that the droplets were 1×10 5 Quench at a rate of °C / sec to produce a flaky solid. The obtained sheet was a brown-red transparent amorphous material...
preparation Embodiment 18-24
[0083] Fine particles were prepared in the same manner as in Preparation Example 1, except that the chemical composition of the mixture was changed to the ratio shown in Table 2, and the sheet was obtained at the crystallization temperature shown in Table 2 Heat for 8 hours. The mineral phase of the fine particles obtained was determined in the same manner as in Preparation Example 1, and as a result, the fine particles were composed of CeO 2 Microparticles with a single phase composition and high crystallinity. In addition, the crystallite diameters of the prepared fine particles were measured in the same manner as in Preparation Example 1, and the results are shown in Table 2. In each of the preparation examples, the crystallite diameters were very small. In addition, it was confirmed that the crystallite diameter increases as the crystallization temperature (heat treatment temperature) increases.
[0084] Table 2
[0085]
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