Abstract: A magnetic disk glass substrate manufacturing method includes a step of polishing a surface of a glass substrate to a mirror surface, a gas heating process step of causing a heated atmosphere and the glass substrate to contact each other so as to heat the glass substrate at a temperature T0, a step of causing a chemically strengthening salt melted exceeding a freezing temperature TF and the glass substrate to contact each other so as to chemically strengthen the glass substrate at a temperature T1, a gas cooling process step of causing a gas coolant and the glass substrate to contact each other so as to cool the glass substrate to a temperature T2, and a liquid cooling process step of causing a liquid coolant and the glass substrate to contact each other so as to cool the glass substrate to a temperature T3, the above-mentioned steps being included in this order, wherein the temperature T2 is set to a temperature less than the freezing temperature TF of the chemical strengthening salt in a gas cooling process

Abstract: In order to prevent particles generated in the preparation of a chemically reinforcing molten salt from getting into an operation atmosphere for performing a chemical reinforcement, a chemical reinforcement tank 2 and a dissolution tank 10 for preparing the chemically reinforcing molten salt are separated from each other. In a typical embodiment, the chemical reinforcement tank is disposed in a clean room 35, and the dissolution tank 10 is disposed outside the clean room.

Abstract: A process for producing a glass substrate for an information recording medium comprising: (a) polishing a principal surface of a glass substrate to provide a polished glass substrate; (b) washing the polished glass substrate with a washing agent; (c) chemically strengthening the glass substrate by immersing the glass substrate in a chemical reinforcement liquid to exchange ions on a surface layer of the glass substrate with ions in the chemical reinforcement liquid having a diameter larger than the ions in the glass substrate; (d) cleaning the surface of the glass substrate with a cleaning agent; (e) drying the surface of the glass substrate; (f) inspecting the surface of the glass substrate; and (g) packing the glass substrate or storing the glass substrate in a container; wherein at least one of the steps (b), (c), (d), (e), (f) and (g) is performed in an atmosphere in which clean filtered air is circulated to prevent particles from being adhered on the surface of the glass substrate.

Abstract: A process for producing a glass substrate for an information recording medium comprising: (a) providing a chemical reinforcement tank comprising a chemical reinforcement liquid contained therein, and a holding means for holding a glass substrate; and (b) chemically strengthening the glass substrate by immersing the glass substrate in the chemical reinforcement liquid, wherein ions are exchanged on the surface of the glass substrate with ions in the chemical reinforcement liquid having a diameter larger than that in the glass substrate; wherein at least one of a wall surface of the chemical reinforcement tank and the holding means is made from a stainless alloy which exhibits corrosion resistance in a high temperature region of the chemical reinforcement liquid, the stainless alloy being made from a martensitic stainless alloy or an austenitic stainless alloy. Such process prevents the adhesion of particles, such as fine iron particles onto the glass substrate.

Abstract: An object of the present invention is to prevent the adhesion of particles such as fine iron powders onto a glass substrate upon the production of a glass substrate for an information recording medium.

Abstract: The surface of a glass substrate withdrawn from a chemically strengthening treatment liquid is processed with a heated acid (for example, a thermal concentrated sulphuric acid at a temperature of over 100.degree. C., or a water soluble organic solvent such as glycerol or polyethylene glycol). Consequently, precipitated fused salt can be effectively removed without damaging the glass substrate and the change in quality of the glass surface can be also prevented at a high level.

Abstract: An object of the present invention is to prevent the dhesion of particles such as fine iron powders onto a glass substrate upon the production of a glass substrate for an information recording medium.

Abstract: A magnetic disk drive of the Winchester type has magnetic disks layered around the external peripheral surface of a spindle and separated mutually from one another by spacers. The substrate of the magnetic disks are made of non-metallic materials such as glass or ceramics but do not break easily by the motion of the spindle or the change in temperature because either the adhesive used to form a unistructural assembly of the magnetic disks and the spacers or elastic members inserted in annular indentations formed in the spacers serve as a buffer when the magnetic disks and the spacers are compressed together.