公开(公告)号：US20210221729A1

公开(公告)日：2021-07-22

申请号：US17055500

申请日：2019-05-14

Applicant: HOYA CORPORATION

Inventor： Koichi SATO ,  Kazuaki HASHIMOTO

IPC: C03C3/091 ,  C03C3/095 ,  C03C3/093 ,  G11B5/73 ,  C03C3/087 ,  C03C3/083 ,  C03C3/078

Abstract: Provided is a glass for a magnetic recording medium substrate, which is an amorphous oxide glass, in which an SiO2 content ranges from 56 mol % to 80 mol %, an Li2O content ranges from 1 mol % to 10 mol %, a B2O3 content ranges from 0 mol % to 4 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cm3 or less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.

公开(公告)号：US20240208859A1

公开(公告)日：2024-06-27

申请号：US18557585

申请日：2022-05-02

Applicant: HOYA CORPORATION

Inventor： Masafumi MIURA ,  Kazuaki HASHIMOTO

IPC: C03C17/245 ,  G11B33/14

CPC classification number: C03C17/2453 ,  G11B33/1433 ,  C03C2217/211 ,  C03C2218/152 ,  C03C2218/365

Abstract: A method for producing a ring-shaped object includes: placing a ring-shaped substrate on a plate; and spraying a gas containing a coating raw material toward a center hole of the ring-shaped substrate from above the ring-shaped substrate placed on the plate to cause the ring-shaped substrate to float up from the plate and form a film on a surface of the ring-shaped substrate.

公开(公告)号：US20240124346A1

公开(公告)日：2024-04-18

申请号：US18390144

申请日：2023-12-20

Applicant: HOYA CORPORATION

Inventor： Koichi SATO ,  Kazuaki HASHIMOTO

IPC: C03C3/091 ,  C03C3/078 ,  C03C3/083 ,  C03C3/087 ,  C03C3/093 ,  C03C3/095 ,  G11B5/73

CPC classification number: C03C3/091 ,  C03C3/078 ,  C03C3/083 ,  C03C3/087 ,  C03C3/093 ,  C03C3/095 ,  G11B5/73921

Abstract: A glass is an amorphous oxide glass. An SiO2 content ranges from 56 mol % to 80 mol %, an Li2O content is 2.00 mol % or less, a B2O3 content ranges from 0 mol % to 4 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cm3 or less, and a glass transition temperature of 650° C. or higher.

公开(公告)号：US20220411317A1

公开(公告)日：2022-12-29

申请号：US17895029

申请日：2022-08-24

Applicant: HOYA CORPORATION

Inventor： Koichi SATO ,  Kazuaki HASHIMOTO

IPC: C03C3/091 ,  G11B5/73 ,  C03C3/078 ,  C03C3/083 ,  C03C3/087 ,  C03C3/093 ,  C03C3/095

Abstract: A glass, which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus, is an amorphous oxide glass. An SiO2 content ranges from 56 mol % to 80 mol %, an Li2O content ranges from 1 mol % to 10 mol %, a B2O3 content ranges from 0 mol % to 4 mol %, a Na2O content is 0 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cm3 or less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.

公开(公告)号：US20210387896A1

公开(公告)日：2021-12-16

申请号：US17357281

申请日：2021-06-24

Applicant: HOYA CORPORATION

Inventor： Koichi SATO ,  Kazuaki HASHIMOTO

IPC: C03C3/091 ,  C03C3/087 ,  C03C3/085 ,  C23C14/35 ,  C23C14/16 ,  G11B5/73 ,  G11B5/65

Abstract: A glass for magnetic recording medium substrate is an amorphous oxide glass. In terms of mol %, SiO2 content ranges from 45 to 68%, Al2O3 from 5 to 20%, total content of SiO2 and Al2O3 60 to 80%, B2O3 from 0 to 5%, MgO from 3 to 28%, CaO from 0 to 18%, total content of BaO and SrO 0 to 2%, total content of alkali earth metal oxides from 12 to 30%, total content of alkali metal oxides from 3.5 to 15%, and at least one kind selected from the group made of Sn oxide and Ce oxide being included, a total content of Sn oxide and Ce oxide ranges from 0.05 to 2.00%, a glass transition temperature ≥625° C., a Young's modulus ≥83 GPa, a specific gravity ≤2.85, and an average linear expansion coefficient at 100 to 300° C.≥48×10−7/° C.

公开(公告)号：US20230192530A1

公开(公告)日：2023-06-22

申请号：US17784528

申请日：2020-12-11

Applicant: HOYA CORPORATION

Inventor： Koichi SATO ,  Kazuaki HASHIMOTO

IPC: C03C3/095 ,  C03C3/087 ,  G11B5/72 ,  G11B5/235

CPC classification number: C03C3/095 ,  C03C3/087 ,  G11B5/72 ,  G11B5/235

Abstract: Provided is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording/reproducing apparatus, in which the total content of Li2O, Na2O, K2O, B2O3, and ZnO (Li2O+Na2O+K2O+B2O3+ZnO) is in a range of 0 mol % or more and 3 mol % or less, the mole ratio of the total content of Al2O3 and MgO relative to the total content of SiO2 and CaO [(Al2O3+MgO)/(SiO2+CaO)] is in a range of 0.30 or more and 0.6 or less, the total content of SiO2 and Al2O3 (SiO2+Al2O3) is in a range of 64 mol % or more and 85 mol % or less, and the total content of SiO2, Al2O3, MgO, and CaO (SiO2+Al2O3+MgO+CaO) is in a range of 87 mol % or more and 98 mol % or less.