Composition, paste and methods
A composition for sealing inorganic substrates, the composition comprising a glass frit and a filler material, wherein said glass frit comprises: 60 to 85 wt % Bi 2 O 3 ; 3 to 15 wt % ZnO; 2 to 10 wt % B 2 O 3 ; 0.6 to 5 wt % SiO 2 ; 0.6 to 5 wt % Al 2 O 3 ; and 0.1 to 0.5 wt % of a compound selected from NaF and BaF 2 .
1. A composition for sealing inorganic substrates, the composition comprising a glass frit and a filler material, wherein said glass frit comprises:
60 to 85 wt % Bi 2 O 3 ;
3 to 15 wt % ZnO;
2 to 10 wt % B 2 O 3 ;
0.5 to 5 wt % SiO 2 ;
0.5 to 5 wt % Al 2 O 3 ; and
0.1 to 0.5 wt % of a compound selected from NaF and BaF 2 , and
wherein said filler material (i) is cordierite or an aluminosilicate glass frit or (ii) is a sintered material comprising an aluminosilicate glass frit and a laser absorber which is a coloured pigment.
2. The composition according to claim 1 , wherein said glass frit comprises 65 to 80 wt %.
3. The composition according to claim 1 , wherein said glass frit comprises 66 to 79 wt % Bi 2 O 3 .
4. The composition according to claim 1 , wherein said glass frit comprises 5 to 12 wt % ZnO.
5. The composition according to claim 1 , wherein said glass frit comprises one or more of the following:
2.5 to 8 wt % B 2 O 3 ;
0.8 to 3 wt % SiO 2 ;
0.8 to 3 wt % Al 2 O 3 ; and,
0.1 to 0.3 wt % of a compound selected from NaF and BaF 2 .
6. The composition according to claim 1 , wherein said glass frit further comprises 0.5 to 5 wt % of one or more alkali metal oxides.
7. The composition according to claim 1 , wherein said glass frit further comprises BaO.
8. The composition according to claim 1 , wherein said glass frit further comprises one or more transition metal oxides.
9. The composition according to claim 1 , wherein said glass frit further comprises a laser absorber which is a coloured pigment.
10. The composition according to claim 1 , which is substantially vanadium-free and/or substantially lead-free.
11. The composition according to claim 1 , further comprising a laser absorber which is a coloured pigment.
12. The composition according to claim 1 , wherein the composition meets one or more of the following requirements:
a wt % ratio of Bi 2 O 3 /ZnO is between 4 and 28;
a wt % ratio of ZnO/B 2 O 3 is between 0.3 and 7.5;
a wt % ratio of Bi 2 O 3 /F is between 120 and 850; and,
a wt % ratio of Bi 2 O 3 /Al 2 O 3 is between 12 and 170.
13. A paste for sealing inorganic substrates, the paste comprising:
(i) a composition according to claim 1 ; and
(ii) an organic medium.
14. 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 paste onto at least a portion of at least one of the inorganic substrates,
the paste comprising (i) 60 to 85 wt % Bi 2 O 3 , 3 to 15 wt % ZnO, 2 to 10 wt % B 2 O 3 , 0.5 to 5 wt % SiO 2 , 0.5 to 5 wt % Al 2 O 3 , and 0.1 to 0.5 wt % of a compound selected from NaF and BaF, and (ii) an organic medium;
(iv) drying said paste to form a dried paste;
(v) optionally pre-firing the dried paste to remove organic medium;
(vi) assembling the first and second substrates such that the dried paste lies therebetween and in contact with both substrates; and
(vii) firing said dried paste.