Patent ID: 7694530
Filing Date: 2010-04-13
Classification: C03C,G11B

Abstract:
1. A chemical strengthening treatment method of a magnetic disk glass substrate, used in an information recording medium for a HDD, wherein a chemical strengthening salt is introduced into a treatment vessel and is melted to obtain a molten chemical strengthening salt and a glass disk is brought into contact with said molten chemical strengthening salt so as to be chemically strengthened, said method comprising: shaping powder into a granular chemical strengthening salt which has a grain size between 1 mm and 10 mm; introducing the granular chemical strengthening salt into the treatment vessel with scattering of the granular chemical strengthening salt being prevented, and melting the granular chemical strengthening salt into a molten chemical strengthening salt with which the substrate is contacted so as to obtain a chemical strengthened magnetic disk glass substrate.