Induction cooking plate and production method

Patent metadata

Field	Value
Publication number	US-10405379-B2
Application number	US-201415106678-A
Country	US
Kind code	B2
Filing date	Dec 15, 2014
Priority date	Dec 20, 2013
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A plate intended for covering or receiving induction heating elements, more particularly an induction cooking plate, said plate being a glass plate with a lithium aluminosilicate-type composition, said plate having a surface zone at least 5 μm thick that includes potassium ions in replacement of the lithium ions of the glass. In addition, an induction cooking appliance incorporating said plate and to a method for producing said plate.

First claim

The invention claimed is:

1. A plate configured to cover or receive one or more induction heating elements,
wherein the plate is a glass plate having a lithium aluminosilicate composition,
wherein the plate has a surface zone comprising potassium ions in replacement of lithium ions of the glass,
wherein the surface zone has a thickness of at least 5 μm, and
wherein a level of potassium at a surface of the glass is greater by at least 3% by weight relative to a level of potassium in a central zone.

2. The plate as claimed in claim 1 , wherein the thickness of the surface zone is between 40 and 120 μm.

3. The plate of claim 1 , wherein a level of potassium at a surface of the glass is greater by 5% to 14% by weight relative to a level of potassium in a central zone.

4. The plate of claim 1 , wherein a level of potassium over a thickness of 5 μm from a surface of the glass reduces by less than 30% after heating at 350° C. for 1000 h.

5. The plate of claim 1 , wherein a flexural breaking stress of the plate before detempering is at least 550 MPa.

6. The plate of claim 1 , having a flexural breaking stress of at least 400 MPa after heating at 350° C. for 1000 h, and/or of at least 550 MPa after heating at 450° C. for 10 minutes.

7. The plate of claim 1 , having a core stress between 2 and 80 MPa for a thickness of 1.5 to 6 mm.

8. The plate of claim 1 , wherein the plate is resistant to formation of flakes by application of a point under a force of 1 N, and/or wherein the plate is resistant to formation of cracks after application of a 500 μm-diameter steel ball under a force of 20 N.

9. The plate of claim 1 , wherein the thickness of the glass plate is less than or equal to 4 mm.

10. The plate of claim 1 , wherein the chemical composition of the glass, initially or at the core of the plate, comprises silica SiO 2 in an amount by weight of from 49% to 75%, alumina Al 2 O 3 in an amount by weight of from 15% to 30%, and lithium oxide Li 2 O in an amount by weight of from 1% to 8%.

11. The plate of claim 1 , wherein the chemical composition of the glass, initially or at the core of the plate, comprises:

SiO 2 :
49%-75%;

Al 2 O 3 :
15%-30%;

Li 2 O:
1%-8%;

K 2 O:
0%-5%;

Na 2 O:
0%-5%;

ZnO:
0%-5%;

MgO:
0%-5%;

CaO:
0%-5%;

BaO:
0%-5%;

SrO:
0%-5%;

TiO 2 :
0%-6%;

ZrO 2 :
0%-5%;

P 2 O 5 :
 0%-10%;

and

B 2 O 3 :
0%-5%.

12. The plate of claim 1 , wherein the chemical composition of the glass, initially or at the core of the plate, comprises:

SiO 2 :
52%-75%;

Al 2 O 3 :
18%-27%;

Li 2 O:
1.5%-5.5%;

K 2 O:
0%-3%;

Na 2 O:
0%-3%;

ZnO:
  0%-3.5%;

MgO:
0%-3%;

CaO:
  0%-4.5%;

BaO:
  0%-3.5%;

SrO:
0%-2%;

TiO 2 :
  0%-5.5%;

ZrO 2 :
0%-3%;

P 2 O 5 :
0%-8%;

and

B 2 O 3 :
0%-3%.

13. The plate of claim 1 , wherein the linear thermal expansion coefficient of the glass is not more than 70×10 −7 /K.

14. A method for manufacturing the plate of claim 1 , the method comprising contacting a lithium aluminosilicate glass plate with at least one potassium salt.

15. The method as claimed in claim 14 , comprising tempering the glass plate in at least one potassium salt bath.

16. The method of claim 15 , further comprising preheating the glass before immersing into the bath, and cooling the glass after withdrawal from the bath.

17. The plate as claimed in claim 1 , wherein the thickness of the surface zone is between 50 and 120 μm from the surface of the glass plate, and the central zone, which is directly adjacent to the surface zone, has a thickness of at least 1.5 mm.

18. An induction cooking appliance comprising:
at least one inductor; and
at least one plate configured to cover or receive one or more induction heating elements,
wherein the plate is a glass plate having a lithium aluminosilicate composition,
wherein the plate has a surface zone comprising potassium ions in replacement of lithium ions of the glass,
wherein the surface zone has a thickness of at least 5 μm, and
wherein a level of potassium at a surface of the glass is

Assignees

• Eurokera

Inventors

• Lestringant Claire
• Gy Rene
• Ferriz Gaelle
• Vilato Pablo

Classifications

• H05B6/12

  Cooking devices · CPC title

• C03C3/097

  containing phosphorus, niobium or tantalum · CPC title

• C03C3/091

  containing aluminium · CPC title

• C03C3/085

  containing an oxide of a divalent metal · CPC title

• C03C3/083 Primary

  containing aluminium oxide or an iron compound · CPC title