Glazing composition for a dental zirconia article, process of sintering and kit of parts
The invention relates to a glazing composition suitable for glazing the surface a dental zirconia article. The glazing composition comprises a liquid, glass particles, and hydrophilic silica nano-particles. The invention also relates to a process for sintering a porous dental zirconia article with a glazing composition on its surface.
1. A glazing composition for a porous dental zirconia article, the glazing composition comprising
liquid,
glass particles, and
hydrophilic silica nano-particles characterized by:
unsilanized,
a particle size (D50) from 10 nm to 70 nm, and
a BET surface from 20 m 2 /g to 500 m 2 /g,
the hydrophilic silica nano-particles being present in an amount of 0.1 wt % to 5 wt % with respect to the weight of the glazing composition.
2. The glazing composition according to claim 1 , the hydrophilic silica nano-particles and the glass particles being present in a ratio of 1:40 to 1:5 with respect to weight.
3. The glazing composition according to claim 1 , the liquid being a polar liquid selected from water, alcohols, polyols and mixtures thereof.
4. The glazing composition according to claim 1 , the glass particles being characterized by the following features alone or in combination:
being present in an amount of 5 to 40 wt. %;
viscosity: at least 10 4 Pa*s at a temperature of 1,300° C.;
coefficient of thermal expansion: 1*10 −6 K −1 to 10*10 −6 K −1 ;
surface tension: of 210 to 300 mN/m at 1,300° C.;
Littleton softening point viscosity at a temperature of 1,100° C. to 1,350° C.;
flow point viscosity at a temperature of 1,300° C. to 1,650° C.;
particle size (D 50 ): 1 to 40 μm;
wt. % with respect to the weight of the glazing composition.
5. The glazing composition according to claim 1 , the glass particles being characterized by comprising one or more of the following compositions:
SiO 2
80 to 98
80 to 98
80 to 98
B 2 O 3
0 to 15
2 to 15
Na 2 O
0 to 5
K 2 O
0 to 5
0.1 to 5
Al 2 O 3
0 to 5
0.1 to 5
0.1 to 5
La 2 O 3
0 to 1
MgO
0 to 5
0.1 to 5
CaO
0 to 2
SrO
0 to 2
BaO
0 to 2
Bi 2 O 3
0 to 0.5
wherein the amounts are given in mol %.
6. The glazing composition according to claim 1 , the glazing composition comprising the components in the following amounts:
liquid: 60 to 95 wt. %,
glass particles: 4 to 40 wt. %,
wt. % with respect to the weight of the glazing composition.
7. The glazing composition according to claim 1 , being characterized by the following features alone or in combination:
viscosity: 10 to 3,000 mPa*s at 23° C.;
pH value: 6 to 9.
8. The glazing composition according to claim 1 , wherein
the liquid is selected from water, an alcohol, a polyol, and a combination thereof in an amount of 60 to 95 wt. %,
the glass particles are present in an amount of 4 to 40 wt. %,
the glass particles have a particle size (D 50 ) of 1 to 40 μm,
a glass of the glass particles is characterized by a viscosity of 10 4 to 10 7 Pa*s at 1,300° C.,
wt. % with respect to the weight of the glazing composition.
9. The glazing composition according to claim 1 , the glass particles further comprising B 2 O 3 , Al 2 O 3 , or a combination thereof.
10. A process of producing a dental zirconia article, the process comprising the steps of
providing a porous dental zirconia article,
applying the glazing composition of claim 1 to at least a part of the surface of the porous dental zirconia article,
sintering the porous dental zirconia article with the glazing composition on its surface to final density.
11. The process according to claim 10 , the porous dental zirconia article being characterized by the following features alone or in combination:
biaxial flexural strength: 15 to 55 determined according to ISO 6872:2015;
Vickers hardness: 15 to 150 (HV 0.5).
12. The process according to claim 10 , the sintering of the porous dental zirconia article being characterized by either of the following conditions:
for regular sintering:
sintering temperature: 1,350 to 1,600° C.,
duration: 50 to 360 min,
heating rate: 1 to 30° C./min;
for fast sintering:
sintering temperature: 1,450 to 1,600° C.,
duration: 10 to 40 min,
heating rate: 60 to 420° C./min.
13. The process according to claim 10 , the process comprising the steps of
providing a porous dental zirconia article with a biaxial flexural strength of 15 to 55 determined according to ISO 6872:2015,
applying the glazing composition to at least a part of the surface of the porous dental zirconia restoration,
sintering the porous dental zirconia article with the glazing composition on its surface to final density.
14. A hydrophilic silica nano-particles binder agent for use in conducting a process according to claim 10 .
15. A kit of parts comprising
the glazing composition of claim 1 ,
a dental zirconia mill blank suitable for producing a dental restoration,
optionally the flowing items alone or in combination:
sintering aids,
application device for the surface treating agent,
a shade guide,
polishing aids,
a sintering oven.
16. A hydrophilic silica nano-particles binder agent for use in producing a glazing composition according to claim 1 .