Kit, particle mixture, paste and methods

1. A particle mixture comprising particles of a first glass frit and particles of a second glass frit; wherein the first glass frit comprises

≥10 to ≤25 mol. % BaO; and

≥0 to ≤10 mol. % Bi 2 O 3 ;

and wherein the second glass frit comprises:

≥35 to ≤55 mol. % Bi 2 O 3 ;

≥2 to ≤20 mol. % ZnO; and

≥10 to ≤40 mol. % B 2 O 3 .

2. The particle mixture as claimed in claim 1 wherein the first glass frit comprises:

≥10 to ≤25 mol. % BaO;

≥0 to ≤10 mol. % Bi 2 O 3 ;

≥15 to ≤35 mol. % ZnO; and

≥15 to ≤35 mol. % B 2 O 3 .

3. The particle mixture as in claim 1 wherein the first glass frit further comprises ≥12 to ≤40 mol. % SiO 2 .

4. The particle mixture as claimed in claim 1 wherein the first glass further comprises ≥1 to ≤20 mol. % transition metal oxide.

5. The particle mixture as claimed in claim 1 where the first glass frit further comprises ≥0.5 to ≤10 mol. % alkali metal oxide.

6. The particle mixture as claimed in claim 1 wherein the second glass frit further comprises ≥2 to ≤15 mol. % SiO 2 .

7. The particle mixture as claimed in claim 1 wherein the second glass frit further comprises ≥0.5 to ≤10 mol. % alkali metal oxide.

8. The particle mixture as claimed in claim 1 wherein the T f of the second glass frit is lower than the T f of the first glass frit.

9. The particle mixture as claimed in claim 1 wherein the T f of the first glass frit is in the range 450 to 800° C.

10. The particle mixture as claimed in claim 1 wherein the T f of the second glass frit is in the range 250 to 700° C.

11. The particle mixture as claimed in claim 1 wherein both the first glass frit and the second glass frit are substantially free of PbO and substantially free of vanadium oxides.

12. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 35 microns.

13. The particle mixture as claimed in claim 1 comprising:

a) ≥25 to ≤75 wt. % particles of the first glass frit;

b) ≥25 to ≤75 wt. % particles of the second glass frit.

14. A particle mixture as claimed in claim 13 which further comprises:

c) ≥5 to ≤10 wt. % particles of filler.

15. The particle mixture as claimed in claim 14 wherein the D90 particle size of the particles of filler is less than or equal to the D90 particle size of one or both of the particles of first glass frit and the particles of second glass frit.

16. A paste comprising:

a) a particle mixture as claimed in claim 1 ; and

b) a dispersion medium.

17. A method of preparing a paste comprising mixing in any order:

a) particles of a first glass frit;

b) particles of a second glass frit; and

c) a dispersion medium;

wherein the first glass frit comprises ≥10 to ≤25 mol. % BaO and ≥0 to ≤10 mol. % Bi 2 O 3 ; and the second glass frit comprises ≥35 to ≤55 mol. % B 2 O 3 , ≥2 to ≤20 mol. % ZnO and ≥10 to ≤40 mol. % boron oxide B 2 O 3 .

18. A method of forming a bond or seal between inorganic substrates, the method comprising:

i. providing a first inorganic substrate;

ii. providing a second inorganic substrate;

iii. depositing a particle mixture as claimed in claim 1 onto at least a portion of at least one of the inorganic substrates;

iv. assembling the first and second substrates such that the deposited particle mixture lies therebetween and in contact with both substrates;

v. firing the particle mixture.

19. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 30 microns.

20. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 25 microns.

21. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 20 microns.

22. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 15 microns.

23. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 10 microns.

24. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 5 microns.

25. The particle mixture as claimed in claim 1 wherein the D90 particle size of each of the first glass frit and the second glass frit is less than 2 microns.

26. The particle mixture as claimed in claim 9 , wherein the T f of the first glass frit is in the range 500 to 700° C.

27. The particle mixture as claimed in claim 10 , wherein the T f of the second glass frit is in the range 300 to 650° C.