Glass having exceptional crack resistance
The present invention pertains to glass containing, in terms of mass % on an oxide basis, 40-80% of SiO 2 , 1-30% of Al 2 O 3 , and 1-40% of CaO, the glass having dmisteinbergite as the crystalline phase. Such glass makes it difficult for cracks to progress and has exceptional crack resistance.
1. A glass:
comprising, in terms of mass % on oxide basis,
SiO 2 40 to 80%,
Al 2 O 3 1 to 30% and
CaO 1 to 40%, and
comprising a dmisteinbergite as a crystalline phase.
2. The glass according to claim 1 ,
wherein the dmisteinbergite has peaks at 2θ in at least the vicinity of 20°, the vicinity of from 23 to 25° and the vicinity of 35° in a diffraction X-ray analysis using Cu-Kα beam as a radiation source.
3. The glass according to claim 1 ,
comprising the dmisteinbergite in an amount of 2% or more in terms of volume fraction (SEM observation).
4. The glass according to claim 1 ,
further comprising at least one of MoO 3 , Fe 2 O 3 , WO 3 , V 2 O 5 , Cr 2 O 3 , Ta 2 O 5 , and TiO 2 .
5. The glass according to claim 4 ,
comprising MoO 3 in an amount of from 0.01 to 1% in terms of mass % on oxide basis.
6. The glass according to claim 4 ,
comprising WO 3 in an amount of from 0.01 to 1% in terms of mass % on oxide basis.
7. The glass according to claim 4 ,
comprising TiO 2 in an amount of from 0.11 to 0.5% in terms of mass % on oxide basis, and
comprising MoO 3 in an amount of from 0.003 to 1% in terms of mass % on oxide basis.
8. The glass according to claim 4 , comprising TiO 2 in an amount of from 0.1 to 0.5% in terms of mass % on oxide basis, and
comprising WO 3 in an amount of from 0.01 to 1% in terms of mass % on oxide basis.
9. A method for manufacturing the glass described in claim 1 , comprising:
melting glass raw materials prepared so as to have the following composition in terms of mass % on oxide basis and to further contain from 0.2 to 5 mass % of C added thereto,
annealing and then,
heat-treating at a temperature of Tg+50° C. or higher and Tg+600° C. or lower (but lower than a liquidus temperature of a glass to be manufactured) wherein Tg (° C.) represents a glass transition point of the glass to be manufactured:
SiO 2 40 to 80%,
Al 2 O 3 1 to 30%, and
CaO 1 to 40%.
10. A method for manufacturing the glass described in claim 1 , comprising:
melting glass raw materials prepared so as to have the following composition in terms of mass % on oxide basis and to further contain from 0.001 to 5 mass % of Si added thereto,
annealing and then,
heat-treating at a temperature of Tg+50° C. or higher and Tg+600° C. or lower (but lower than a liquidus temperature of a glass to be manufactured) wherein Tg (° C.) represents a glass transition point of the glass to be manufactured:
SiO 2 40 to 80%,
Al 2 O 3 1 to 30%, and
CaO 1 to 40%.
11. The method for manufacturing the glass, according to claim 10 ,
wherein the glass raw materials containing from 0.001 to 0.2 mass % of Si added thereto is melted.
12. The glass according to claim 1 , obtained by:
melting glass raw materials prepared so as to have the following composition in terms of mass % on oxide basis and to further contain from 0.001 to 0.2 mass % of Si added thereto,
annealing and then,
heat-treating at a temperature of Tg+50° C. or higher and Tg+600° C. or lower (but lower than a liquidus temperature of a glass to be manufactured) wherein Tg (° C.) represents a glass transition point of the glass to be manufactured:
SiO 2 40 to 80%,
Al 2 O 3 1 to 30%, and
CaO 1 to 40%.