Process for producing a glazed ceramic body
A process for producing a glazed ceramic body, in which a glazing material is applied to a non-densely sintered substrate material and the substrate material and the glazing material are subjected to a heat treatment in order to obtain the glazed body.
1. Process for producing a glazed ceramic body, comprising
(a) a glazing material is applied to a non-densely sintered substrate material having a relative density in the range of from 30 to 90%, based on the true density of the substrate material, and
(b) the substrate material and the glazing material are subjected to a heat treatment in a temperature range which extends from a first temperature T 1 to a second temperature T 2 , which is higher than the first temperature, in order to obtain the glazed body,
wherein, at the temperature T 1 , the glazing material has a viscosity of more than 10 2.5 Pa·s, and, at the temperature T 2 , the glazing material has a viscosity of less than 10 9 Pa·s and the substrate material has a relative density of at least 97%, based on the true density of the substrate material.
2. Process according to claim 1 , in which, at the temperature T 1 , the glazing material has a viscosity of more than 10 5.6 Pa·s, and, at the temperature T 2 , a viscosity of less than 10 5.6 Pa·s.
3. Process according to claim 1 , in which the non-densely sintered substrate material is a presintered substrate material.
4. Process according to claim 1 , in which the non-densely sintered substrate material has a relative density in the range of from 40 to 80, based on the true density of the substrate material.
5. Process according to claim 1 , in which the substrate material begins to sinter at the temperature T 1 .
6. Process according to claim 1 , in which the substrate material is kept at the temperature T 2 for a period of 5 to 120 minutes.
7. Process according to claim 1 , in which, at the temperature T 2 , the substrate material has a relative density of at least 98%, based on the true density of the substrate material.
8. Process according to claim 1 , in which, at a temperature T x , at which the substrate material has a relative density of 95%, based on the true density of the substrate material, the glazing material has a viscosity of more than 10 2.5 Pa·s.
9. Process according to claim 1 , in which the glazing material has, at the temperature T 1 , a viscosity of more than 10 5.6 Pa·s, at the temperature T x , at which the substrate material has a relative density of 95%, based on the true density of the substrate material, a viscosity of more than 10 2.5 Pa·sand, at the temperature T 2 , a viscosity of less than 10 9 Pa·s.
10. Process according to claim 1 , in which the substrate material is an oxide ceramic or an inorganic-inorganic composite material.
11. Process according to claim 1 , in which the substrate material comprises at least two layers, which differ in their colour.
12. Process according to claim 1 , in which, at a temperature of 950° C., the glazing material has a viscosity of more than 10 2.5 Pa·s, at a temperature of 1300° C., a viscosity of more than 10 2.5 Pa·s and, at a temperature of 1450° C., a viscosity of less than 10 9 Pa·s.
13. Process according to claim 1 , in which, at a temperature of 700° C., the glazing material has a viscosity of more than 10 2.5 Pa·s, at a temperature of 900° C., a viscosity of more than 10 2.5 Pa·s and, at a temperature of 1100° C., a viscosity of less than 10 9 Pa·s.
14. Process according to claim 1 , in which the glazing material comprises a frit, which comprises SiO 2 , Al 2 O 3 and K 2 O and/or Na 2 O, and contains at least one or all of the following components in the given amounts:
Component
wt.-%
SiO 2
50.0 to 80.0
Al 2 O 3
10.0 to 30.0
K 2 O
0 to 20.0
Na 2 O
0 to 10.0
CaO
0 to 10.0
BaO
0 to 10.0.
15. Process according to claim 1 , in which the glazing material is applied to the substrate material in the form of a powder, a slip, a spray or a lacquer, or by an airbrushing method or incorporated into a film or an adhesive strip.
16. Process according to claim 1 , in which the glazing material is used in the form of a composition which further comprises at least one carrier, solvent, inorganic filler and/or organic filler.
17. Process according to claim 1 , in which the glazing material does not substantially penetrate into the substrate material.
18. Process according to claim 1 , in which the glazed ceramic body is a glazed dental body, a glazed dental restoration, a bridge, an inlay, an onlay, a crown, a veneer, a facet or an abutment.
19. Process of using a glazing material for glazing a non-densely sintered substrate material,
wherein the glazing material is applied to the non-densely sintered substrate material having a relative density in the range of from 30 to 90%, based on the true density of the substrate material, and the substrate material and the glazing material are subjected to a heat treatment in a temperature range which extends from a first temperature T 1 to a second temperature T 2 , which is higher than the first temperature, wherein, at the temperature T 1 , the glazing material has a viscosity of more than 10 2.5 Pa·s and, at the temperature T 2 , a viscosity of less than 10 9 Pa·s and the substrate material has a relative density of at least 97%, based on the true density of the substrate material.