Fusion sealing materials

• US 5,089,445 A
• Filed: 10/09/1990
• Issued: 02/18/1992
• Est. Priority Date: 10/09/1990
• Status: Expired due to Fees

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Francis, Gaylord L.
• Primary Examiner(s): BELL, MARK LEE
• Application Number:
  US07/594,629
• Time in Patent Office: 497 Days
• Field of Search: 501/15, 501/17, 501/32, 501/10, 501/19
• US Class Current: 501/15
• CPC Class Codes: C03C 8/14 Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
• CPC Class Codes: C03C 8/24 Fusion seal compositions being frit compositions having non-frit additions, i.e. for use as seals between dissimilar materials, e.g. glass and metal; Glass solders
• CPC Class Codes: C03C 8/245 containing more than 50% lead oxide, by weight

Abstract

There is disclosed a sealing material based on a lead sealing glass having a mill addition of a crystalline material having the crystalline structure of magnesium pyrophosphate. The effective coefficient of thermal expansion in a seal is substantially reduced by the mill addition, thereby permitting use with low expansion materials.

Claims

1. A sealing material comprising a lead sealing glass and a mill addition of a pyrophosphate crystalline material selected from the group consisting of magnesium pyrophosphate, a magnesium pyrophosphate with at least a portion of the magnesium ions replaced by at least one cation selected from the group composed of cobalt, arsenic, zinc, iron, aluminum and zirconium, and a crystallized phosphate glass composed essentially of P₂ O₅ and one or more cations selected from the group composed of magnesium, cobalt, arsenic, zinc, iron, aluminum and zirconium.

2. A sealing material in accordance with claim 1 wherein the lead sealing glass is a lead borate glass.

3. A sealing material in accordance with claim 2 wherein the lead sealing glass is a lead zinc borate glass.

4. A sealing material in accordance with claim 1 wherein the lead sealing glass is a lead borosilicate.

5. A sealing material in accordance with claim 1 wherein the lead sealing glass is a lead titanate glass.

6. A sealing material in accordance with claim 1 wherein the mill addition is magnesium pyrophosphate.

7. A sealing material in accordance with claim 1 wherein the mill addition is magnesium pyrophosphate with a portion of the magnesium cations replaced by at least one cation selected from the group composed of cobalt, arsenic, zinc, iron, aluminum, and zirconium.

8. A sealing material in accordance with claim 7 wherein the replacing cation in the magnesium pyrophosphate is cobalt.

9. A sealing material in accordance with claim 7 wherein the replacing cation in the magnesium pyrophosphate is zinc.

10. A sealing material in accordance with claim 1 wherein the selected mill addition is composed of at least two different pyrophosphate crystalline materials with at least one being a magnesium pyrophosphate with at least a portion of the magnesium cations being replaced by at least one cation selected from the group composed of cobalt, arsenic, zinc, iron, aluminum and zirconium.

11. A sealing material in accordance with claim 10 wherein one of the crystalline materials is magnesium pyrophosphate.

12. A sealing material in accordance with claim 10 wherein the selected mill addition is a crystallized phosphate glass composed essentially of P₂ O₅ and one or more cations selected from the group composed of magnesium, cobalt, arsenic, zinc, iron, aluminum and zirconium.

13. A sealing material in accordance with claim 12 wherein the mill addition is a crystallized glass composed essentially of MgO and P₂ O₅ in about the stoichiometric molar ratio of magnesium pyrophosphate.

14. A sealing material in accordance with claim 13 wherein the crystallized glass composition further includes at least one oxide selected from the group composed of cobalt, arsenic, zinc, aluminum, iron and zirconium, and the molar ratio of the total of such selected oxide(s) plus MgO to the P₂ O₅ is about the stoichiometric molar ratio of magnesium pyrophosphate.

15. A sealing material in accordance with claim 14 wherein the selected oxide is cobalt oxide.

16. A sealing material in accordance with claim 14 wherein the selected oxide is zinc oxide.

17. A sealing material in accordance with claim 1 wherein the sealing material additionally contains Invar particles.

18. A sealing material in accordance with claim 1 wherein the mill addition constitutes not more than about 20% by volume of the material.

19. A fusion seal composed of a fused mixture comprising a lead sealing glass and, dispersed therein, a mill addition of a crystalline material selected from the group composed of magnesium pyrophosphate, a magnesium pyrophosphate with at least a portion of the magnesium ions replaced by at least one cation selected from the group composed of cobalt, arsenic, zinc, iron, aluminum and zirconium and a crystallized phosphate glass composed essentially of P₂ O₅ and one or more cations selected from the group composed of magnesium, cobalt, arsenic, zinc, iron, aluminum and zirconium.

20. A fusion seal in accordance with claim 19 wherein the lead sealing glass is a lead borate glass.

21. A fusion seal in accordance with claim 20 wherein the lead sealing glass is a lead zinc borate glass.

22. A fusion seal in accordance with claim 19 wherein the lead sealing glass is a lead borosilicate.

23. A fusion seal in acordance with claim 19 wherein the lead sealing glass is a lead titanate glass.

24. A fusion seal in accordance with claim 19 wherein the mill addition is magnesium pyrophosphate.

25. A fusion seal in accordance with claim 19 wherein the mill addition is magnesium pyrophosphate with a portion of the magnesium cations replaced by at least one cation selected from the group composed of cobalt, arsenic, zinc, iron, aluminum, and zirconium.

26. A fusion seal in accordance with claim 25 wherein the replacing cation in the magnesium pyrophosphate is cobalt.

27. A fusion seal in accordance with claim 25 wherein the replacing cation in the magnesium pyrophosphate is zinc.

28. A fusion seal in accordance with claim 19 wherein the selected mill addition is composed of at least two different pyrophosphate crystalline materials with at least one being a magnesium pyrophosphate with at least a portion of the magnesium cations being replaced by at least one cation selected from the group composed of cobalt, arsenic, zinc, iron, aluminum and zirconium.

29. A fusion seal in accordance with claim 28 wherein one of the crystalline material is magnesium pyrophosphate.

30. A fusion seal in accordance with claim 19 wherein the selected mill addition is a crystallized phosphate glass composed essentially of P₂ O₅ and one or more cations selected from the group composed of magnesium, cobalt, arsenic, zinc, iron, aluminum and zirconium.

31. A fusion seal in accordance with claim 30 wherein the mill addition is a crystallized glass composed essentially of MgO and P₂ O₅ in about the stoichiometric molar ratio of magnesium pyrophosphate.

32. A fusion seal in accordance with claim 31 wherein the crystallized glass composition further includes at least one oxide selected from the group composed of cobalt, arsenic, zinc, aluminum, iron and zirconium, and the molar ratio of the total of such selected oxide(s) plus MgO to the P₂ O₅ is about the stoichiometric molar ratio of magnesium pyrophosphate.

33. A fusion seal in accordance with claim 32 wherein the selected oxide is cobalt oxide.

34. A fusion seal in accordance with claim 32 wherein the selected oxide is zinc oxide.

35. A fusion seal in accordance with claim 19 wherein the seal additionally contains Invar particles.

36. A fusion seal in accordance with claim 19 wherein the mill addition constitutes not more than about 20% by volume of the material.