# US 11,028,015 B2 · Glass ball having specific Young's modulus and coefficient of thermal expansion

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- Number: US 11,028,015 B2
- Document ID: US11028015B2
- Status: Granted
- Kind: B2
- Application number: 16/729,839
- Filed: 2019-12-30
- Published: 2020-04-30
- Granted: 2021-06-08
- Earliest claimed: 2017-07-04
- Assignees: AGC Inc.
- Applicants: AGC Inc.
- Inventors: Akio Koike; Makoto Katsuta; Suguru Murayama; Kenji Imakita
- Web page: https://patentgrep.com/patent/US11028015B2

## CPC

- C03C 12/00: Powdered glass (C03C8/02 takes precedence); Bead compositions
- C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)}
- C03C 3/062: with less than 40% silica by weight
- C03C 3/064: containing boron
- C03C 3/083: containing aluminium oxide or an iron compound
- C03C 3/085: containing an oxide of a divalent metal
- C03C 3/087: containing calcium oxide, e.g. common sheet or container glass
- C03C 3/091: containing aluminium
- C03C 3/095: containing rare earths
- F16C 33/32: Balls
- C01P 2004/32: Spheres
- C01P 2006/10: Solid density
- C01P 2006/32: Thermal properties
- F16C 2202/04: Hardness
- F16C 2202/22: Coefficient of expansion
- F16C 2202/32: Conductivity
- F16C 2206/42: based on ceramic oxides
- F16C 2240/70: Diameters; Radii
- F16C 2300/22: High-speed rotation
- F16C 2362/52: Compressors of refrigerators, e.g. air-conditioners
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

A glass ball has a density of 2.3 to 3.2 g/cm3, a Young's modulus of 60 to 150 GPa, and an average coefficient of thermal expansion at 50 to 350° C. being 40×10−7 to 120×10−7/° C. The glass ball is formed of a glass material including, as represented by mole percentage based on oxides, 30 to 75 mol % of SiO2, 2 to 30 mol % of Al2O3, and 5 to 25 mol % of R2O, where R is at least one kind selected from Li, Na and K. The glass ball includes a compressive stress layer in a surface thereof.

## Claims

### Claim 1

A glass ball, having:
a density of 2.3 to 3.2 g/cm3;
a Young's modulus of 60 to 150 GPa; and
an average coefficient of thermal expansion at 50 to 350° C. being 40×10−7 to 120×10−7/° C.,
the glass ball being formed of a glass material comprising, as represented by mole percentage based on oxides, 30 to 75 mol % of SiO2, 2 to 30 mol % of Al2O3, and 5 to 25 mol % of R2O, wherein R is at least one kind selected from Li, Na and K, and
the glass ball comprising a compressive stress layer in a surface thereof.

### Claim 2 (depends on 1)

The glass ball according to claim 1, wherein the compressive stress layer has a depth (DOL) of 8 to 500 μm.

### Claim 3 (depends on 1)

The glass ball according to claim 1, wherein the glass material is a Li-based glass comprising, as represented by mole percentage based on oxides, 50 to 75 mol % of SiO2, 4 to 20 mol % of Al2O3, 1 to 15 mol % of Li2O, 5 to 25 mol % of R2O, and 0 to 15 mol % of MgO, wherein R is at least one kind selected from Li, Na and K, and SiO2+Al2O3+R2O+MgO is 92 mol % or higher.

### Claim 4 (depends on 1)

The glass ball according to claim 1, wherein the glass material is a Y2O3-based glass comprising, as represented by mole percentage based on oxides, 30 to 70 mol % of SiO2, 4 to 30 mol % of Al2O3, 5 to 20 mol % of Li2O, 5 to 25 mol % of R2O, 1 to 25 mol % of MgO, and 1 to 20 mol % of Y2O3, wherein R is at least one kind selected from Li, Na and K.

### Claim 5 (depends on 1)

The glass ball according to claim 1, having a surface compressive stress value (CS0) of 200 to 1,500 MPa.

### Claim 6 (depends on 1)

The glass ball according to claim 1, having a Vickers hardness (Hvct) of 6.0 GPa or more.

### Claim 7 (depends on 1)

The glass ball according to claim 1, having a diameter of 0.5 to 100 mm.

### Claim 8 (depends on 1)

The glass ball according to claim 1, wherein a molar ratio of an amount of Li2O to R2O is at least 0.56.

### Claim 9 (depends on 1)

The glass ball according to claim 1, wherein a molar ratio of an amount of Li2O to R2O is at least 0.63.

### Claim 10 (depends on 1)

The glass ball according to claim 1, wherein a molar ratio of an amount of Li2O to R2O is at least 0.75.