Crystallized glass, substrate for magnetic disc, magnetic disc and method of producing crystallized glass
AssigneeNGK Insulators, Ltd.
InventorsMasahiro Abe, Takahiro Takahashi
Life of this patent
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Abstract
A crystallized glass has a main crystal phase of α-quartz (SiO2) and lithium disilicate (Li2·2SiO2) and has a thermal expansion coefficient of (90˜130)×10−7/K at −50° C.˜70° C. The crystallized glass mentioned above, has a following chemical composition; 70 wt %≦SiO2≦80 wt %, 5 wt %≦Al2O3≦9 wt %, 7 wt %≦Li2O≦10 wt %, 1 wt %≦P2O5≦3 wt %, 0 wt %≦K2O≦3 wt %, 0 wt %≦CaO≦3 wt %, 0 wt %≦BaO≦4 wt %, 0 wt %≦ZnO≦4 wt %, 0 wt %≦Sb2O3≦1 wt %, 0 wt %≦ZrO2≦6 wt %, 0 wt %≦Nb2O5≦6 wt %, 0 wt %≦SnO2≦4 wt %, 0 wt %≦MoO3≦3 wt %, 0.7 wt %≦(Nb2O5+SnO2+MoO3)≦6 wt %.
Claims6
A crystallized glass, which has a main crystal phase of α-quartz (SiO2) and lithium disilicate (Li2O·2SiO2) and has a thermal expansion coefficient of (90˜130)×10−7/K at −50° C.˜70 ° C., comprising a following chemical composition;
- 70 wt %≦SiO2≦80 wt %, 5 wt %≦Al2O3≦9 wt %, 7 wt %≦Li2O<10 wt %, 1 wt %≦P2O5≦3 wt %, 0 wt %≦K2O≦3 wt %, 0 wt %≦CaO≦3 wt %, 0 wt %≦BaO≦4 wt %, 0 wt %≦ZnO≦4 wt %, 0 wt %≦Sb2O3≦1 wt %, 0 wt %≦ZrO2≦6 wt %, 0 wt %≦Nb2O5≦6 wt %, 0 wt %≦SnO2≦4 wt %, 0 wt %≦MoO3≦3 wt %, 0.7 wt %≦(Nb2O5+SnO2+MoO3)≦6 wt %.
A method of producing a crystallized glass comprising the steps of;
- preparing a parent glass having the following chemical composition, subjecting the parent glass to a heat treatment at 570° C.˜640° C. so as to perform a nucleus generation, and subjecting the parent glass to a heat treatment at 670° C.˜750° C. so as to crystallize the parent glass;
- 70 wt %≦SiO223 80 wt %, 5 wt %≦Al2O3≦9 wt %, 7 wt %≦Li2O<10 wt %, 1 wt %≦P2O5≦3 wt %, 0 wt %≦K2O≦3 wt %, 0 wt %≦CaO≦3 wt %, 0 wt %≦BaO≦4 wt %, 0 wt %≦ZnO≦4 wt %, 0 wt %≦Sb2O3≦1 wt %, 0 wt %≦ZrO2≦6 wt %, 0 wt %≦Nb2O5≦6 wt %, 0 wt %≦SnO2≦4 wt %, 0 wt %≦MoO3≦3 wt %, 0.7 wt %≦(Nb2O5+SnO2+MoO3)≦6 wt %.
Dependencies are inferred from the claim text.