Spark plug with improved seal

1. An electrically conductive glass seal for a spark plug, comprising:

at least one glass in a total amount of 50.0 to 85.0 weight (wt. %), based on the total weight of said glass seal;

electrically conductive metal particles in an amount of 15.0 to 50.0 wt. %, based on the total weight of said glass seal;

wherein said glass seal includes gas-filled pores in an amount of 25.0 to 75.0 volume percent (vol. %), based on the total volume of said glass seal; and

said glass seal is electrical conductive.

2. The electrically conductive glass seal of claim 1 , wherein said glass includes silica (SiO 2 ), boron oxide (B 2 O 3 ), aluminum oxide (Al 2 O 3 ), bismuth oxide (Bi 2 O 3 ), and zinc oxide (ZnO); and said electrically conductive particles include copper.

3. The electrically conductive glass seal of claim 1 , wherein said glass includes silica (SiO 2 ) in an amount of 35.0 to 40.0 wt. %, boron oxide (B 2 O 3 ) in an amount of 20.0 to 28.0 wt. %, aluminum oxide (Al 2 O 3 ) in an amount of 10.0 to 15.0 wt. %, bismuth oxide (Bi 2 O 3 ) in an amount of 10.0 to 15.0 wt. %, and zinc oxide (ZnO) in an amount of 3.0 to 5.0 wt. %, based on the total weight of said glass.

4. The electrically conductive glass seal of claim 3 , wherein said glass further includes alkali metal oxides in a total amount of 2.0 to 6.0 wt. % and alkaline earth metal oxides in a total amount of 3.0 to 7.0 wt. %, based on the total weight of said glass.

5. The electrically conductive glass seal of claim 1 , wherein said gas-filled pores are present in an amount of 35.0 to 45.0 vol. %, based on the total volume of said glass seal.

6. The electrically conductive glass seal of claim 1 , wherein said gas-filled pores are spaced from one another by said glass and said electrically conductive metal particles.

7. The electrically conductive glass seal of claim 1 , wherein said electrically conductive metal particles include copper.

8. The electrically conductive glass seal of claim 7 , wherein said electrically conductive metal particles include flakes of the copper and have a particle size of less than 45 microns.

9. The electrically conductive glass seal of claim 1 , wherein said glass seal has an electrical conductivity ranging from 9×10 6 S/m to 65×10 6 S/m.

10. The electrically conductive glass seal of claim 9 , wherein said glass seal has an electrical conductivity above 30×10 6 S/m.

11. A spark plug, comprising:

an electrically conductive component;

an insulator surrounding said electrically conductive component;

an electrically conductive glass seal providing a hermetic bond between said electrically conductive component and said insulator;

said electrically conductive glass seal including at least one glass in a total amount of 50.0 to 85.0 wt. %, and electrically conductive metal particles in an amount of 15.0 to 50.0 wt. %, based on the total weight of the glass seal;

wherein the glass seal includes gas-filled pores in an amount of 25.0 to 75.0 vol. %, based on the total volume of the glass seal; and

the glass seal is electrical conductive.

12. The spark plug of claim 11 , wherein said gas-filled pores are present in an amount of 35.0 to 45.0 vol. %, based on the total volume of said glass seal; and said gas-filled pores are spaced from one another by said glass and said electrically conductive metal particles.

13. The spark plug of claim 11 , wherein said electrically conductive glass seal has an electrical conductivity ranging from 9×10 6 S/m to 65×10 6 S/m.

14. A method of manufacturing a glass seal for a spark plug, comprising the steps of:

providing a mixture including at least one glass frit in a total amount of 48.8 to 85.0 wt. %, a binder in an amount of 0.1 to 3.0 wt. %, an expansion agent in an amount of 0.1 to 1.0 wt. %, and electrically conductive metal particles in an amount of 14.8 to 50.0 wt. %, based on the total weight of the mixture; and

firing the mixture to form the glass seal, wherein the glass seal is electrically conductive.

15. The method of claim 14 , wherein the expansion agent converts to a gas during the firing step and provides a plurality of pores filled with the gas, and the pores are spaced from one another by the electrically conductive particles and the glass after allowing the glass seal to cool to room temperature.

16. The method of claim 14 , wherein the binder of the mixture includes an inorganic binder in an amount of 0.1 to 2.0 wt. % and an organic binder in an amount of 0.1 to 1.0 wt. %, based on the total weight of the mixture; and at least a portion of the binder burns off during the firing step.

17. A method of manufacturing a spark plug, comprising the steps of:

disposing a mixture between an electrically conductive component and an insulator, wherein the mixture comprises at least one glass frit in a total amount of 48.8 to 85.0 wt. %, a binder in an amount of 0.1 to 3.0 wt. %, an expansion agent in an amount of 0.1 to 1.0 wt. %, and electrically conductive metal particles in an amount of 14.8 to 50.0 wt. %, based on the total weight of the mixture; and

firing the mixture to form the glass seal, wherein the glass seal is electrically conductive.

18. The method of claim 17 , wherein the glass seal provides a hermetic bond between the electrically conductive component and the insulator after the firing step.

19. The method of claim 17 , wherein the expansion agent converts to a gas during the firing step and provides a plurality of pores filled with the gas, and the pores are spaced from one another by the electrically conductive particles and the glass after allowing the glass seal to cool to room temperature.

20. The method of claim 17 , wherein the binder of the mixture includes an inorganic binder in an amount of 0.1 to 2.0 wt. % and an organic binder in an amount of 0.1 to 1.0 wt. %, based on the total weight of the mixture; and at least a portion of the binder burns off during the firing step.

21. An electrically conductive glass seal for a spark plug, comprising:

at least one glass in a total amount of 72.0 to 82.0 weight (wt. %), based on the total weight of said glass seal;

electrically conductive metal particles in an amount of 15.0 to 25.0 wt. %, based on the total weight of said glass seal;

wherein said glass seal includes gas-filled pores in an amount of 25.0 to 75.0 volume percent (vol. %), based on the total volume of said glass seal; and

said glass seal is electrical conductive.

22. The electrically conductive glass seal of claim 21 , wherein said electrically conductive metal particles include flakes of copper.

23. The electrically conductive glass seal of claim 21 , wherein said glass includes silica (SiO 2 ) in an amount of 60.0 to 70.0 wt. %, boron oxide (B 2 O 3 ) in an amount of 17.0 to 25.0 wt. %, aluminum oxide (Al 2 O 3 ) in an amount of 4.0 to 10.0 wt. %, alkali metal oxides in an amount of 3.0 to 10.0 wt. %, and alkaline earth metal oxides in an amount of 0.0 to 5.0 wt. %, based on the total weight of said glass.

24. A spark plug, comprising:

an electrically conductive component;

an insulator surrounding said electrically conductive component;

an electrically conductive glass seal providing a hermetic bond between said electrically conductive component and said insulator;

said electrically conductive glass seal including at least one glass in a total amount of 72.0 to 82.0 wt. %, and electrically conductive metal particles in an amount of 15.0 to 25.0 wt. %, based on the total weight of the glass seal;

wherein the glass seal includes gas-filled pores in an amount of 25.0 to 75.0 vol. %, based on the total volume of the glass seal; and

the glass seal is electrical conductive.

25. A method of manufacturing a glass seal for a spark plug, comprising the steps of:

providing a mixture including at least one glass frit in a total amount of 72.0 to 82.0 wt. %, an inorganic binder in an amount of 1.0 to 5.0 wt. %, an expansion agent in an amount of 0.1 to 0.5 wt. %, and electrically conductive metal particles in an amount of 15.0 to 25.0 wt. %, based on the total weight of the mixture; and

firing the mixture to form the glass seal, wherein the glass seal is electrically conductive.

26. The method of claim 25 , wherein the inorganic binder includes bentonite, the expansion agent includes calcium carbonate, and the electrically conductive metal particles include flakes of copper.

27. A method of manufacturing a spark plug, comprising the steps of:

disposing a mixture between an electrically conductive component and an insulator, wherein the mixture comprises at least one glass frit in a total amount of 72.0 to 82.0 wt. %, an inorganic binder in an amount of 1.0 to 5.0 wt. %, an expansion agent in an amount of 0.1 to 0.5 wt. %, and electrically conductive metal particles in an amount of 15.0 to 25.0 wt. %, based on the total weight of the mixture; and

firing the mixture to form the glass seal, wherein the glass seal is electrically conductive.