Exuded transition metal films on glass-ceramic articles

Claim 1

A method of providing a glass-ceramic article having an exuded surface film comprising at least one transition metal compound selected from the group consisting of Mn 3 O 4 , Fe 3 O 4 , Co 3 O 4 , NiAl 2 O 4 , CoAl 2 O 4 , MnAl 2 D 4 , 2O 4 , ValO 4 , NiFe 2 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , MnTiO 3 , CoTiO 3 , FeTiO 3 , Co 2 TiO 4 and CoMn 2 O 4 on at least a portion of the surface thereof which comprises the steps of: a. compounding a batch for a glass composition consisting essentially, in weight percent on the oxide basis as calculated from the batch, of about 55-80% SiO 2 , 14-35% Al 2 O 3 , 0-5% Li 2 O, 0-7% TiO 2 , 0-10% ZrO 2 , 3-13% total of said TiO 2 + ZrO 2 , 0-3% F, and 0.1-10% total of transition metal oxide additives containing one or more of the transition metals manganese, iron, cobalt, chromium, nickel and vanadium in a combination which will provide one or more of said Mn 3 O 4 , Fe 3 O 4 , Co 3 O 4 , NiAl 2 O 4 , CoAl 2 O 4 , MnAl 2 O 4 , FeAl 2 O 4 , VAlO 4 , NiFe 2 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , MnTiO 3 , CoTiO 3 , FeTiO 3 , Co 2 TiO 4 and CoMn 2 O 4 transition metal compounds on the surface of said article, said additives being selected in the indicated proportions from the group consisting of 0-5% MnO 2 , 0-5% Fe 2 O 3 , 0-3% CoO, 0-2% Cr 2 O 3 , 0-3% V 2 O 5 and 0-10% NiO, the foregoing constituents comprising at least about 90% by weight of said composition and said composition being capable of forming a principle crystal phase selected from the group consisting of beta-spodumene and beta-quartz solid solutions upon thermal crystallization thereof; b. melting said batch at a temperature in the range of about 1600°-1650° C. for a time in the range of about 6-16 hours to provide a molten glass; c. forming the molten glass into a glass article; d. exposing the glass article to a temperature in the range of about 700°-800° C. for a time in the range of about 1-4 hours to obtain nucleation of the glass; e. thereafter exposing the article to a temperature in the range of about 800°-1200° C. for a time in the range of about 1-8 hours to obtain crystallization of the glass by the formation of a principal crystal phase selected from the group consisting of beta-quartz and beta-spodumene solid solution therein; and f. exposing the article to a temperature in the range of about 500°-1000° C. in a reducing atmosphere for a time in the range of about 1/2-10 hours to develop said exuded surface film comprising said transition metal compounds thereon.

Claim 2

A method of providing a glass-ceramic article having an exuded surface film comprising at least one transition metal compound selected from the group consisting of Mn 3 O 4 , Fe 3 O 4 , Co 3 O 4 , NiAl 2 O 4 , CoAl 2 O 4 , MnAl 2 D 4 , 2O 4 , ValO 4 , NiFe 2 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , MnTiO 3 , CoTiO 3 , FeTiO 3 , Co 2 TiO 4 and CoMn 2 O 4 on at least a portion of the surface thereof which comprises the steps of: a. compounding a batch for a glass composition consisting essentially, in weight percent on the oxide basis as calculated from the batch, of about 55-80% SiO 2 , 14-35% Al 2 O 3 , 0-5% Li 2 O, 0-7% TiO 2 , 0-10% ZrO 2 , 3-13% total of said TiO 2 + ZrO 2 , 0-3% F, and 0.1-10% total of transition metal oxide additives containing one or more of the transition metals manganese, iron, cobalt, chromium, nickel and vanadium in a combination which will provide one or more of said Mn 3 O 4 , Fe 3 O 4 , Co 3 O 4 , NiAl 2 O 4 , CoAl 2 O 4 , MnAl 2 O 4 , FeAl 2 O 4 , VAlO 4 , NiFe 2 O 4 , CoFe 2 O 4 , MnFe 2 O 4 , MnTiO 3 , CoTiO 3 , FeTiO 3 , Co 2 TiO 4 and CoMn 2 O 4 transition metal compounds on the surface of said article, said additives being selected in the indicated proportions from the group consisting of 0-5% MnO 2 , 0-5% Fe 2 O 3 , 0-3% CoO, 0-2% Cr 2 O 3 , 0-3% V 2 O 5 and 0-10% NiO, the foregoing constituents comprising at least about 90% by weight of said composition and said composition being capable of forming a principle crystal phase selected from the group consisting of beta-spodumene and beta-quartz solid solutions upon thermal crystallization thereof; b. melting said batch at a temperature in the range of about 1600°-1650° C. for a time in the range of about 6-16 hours to provide a molten glass; c. forming the molten glass into a glass article; d. exposing the glass article to a temperature in the range of about 700°-800° C. for a time in the range of about 1-4 hours to obtain nucleation of the glass; e. thereafter exposing the article to a temperature in the range of about 800°-1200° C. for a time in the range of about 1-8 hours to obtain crystallization of the glass by the formation of a principal crystal phase selected from the group consisting of beta-quartz and beta-spodumene solid solution therein; and f. exposing the article to a temperature in the range of about 500°-1000° C. in a reducing atmosphere for a time in the range of about 1/2-10 hours to develop said exuded surface film comprising said transition metal compounds thereon.

Claim 6

A method of providing a glass-ceramic article having an exuded ferromagnetic surface film comprising at least one transition metal compound selected from the group consisting of Mn 3 O 4 , Fe 3 O 4 , MnAl 2 O 4 , NiAl 2 O 4 , NiFe 2 O 4 , MnFe 2 O 4 , MnCr 2 O 4 , MnNb 2 O 6 , NiNb 2 O 6 , Ti 2 Nb 10 O 29 , and Mn 2 Al 2 (SiO 4 ) 2 on at least a portion of the surface thereof which comprises the steps of: a. compounding a batch for a glass composition consisting essentially, in weight percent on the oxide basis as calculated from the batch, of about 10-60% MnO 2 , at least one oxide selected in the indicated proportion from the group consisting of 10-70% SiO 2 , 13-43% Al 2 O 3 , and 0-35% B 2 O 3 , essentially including at least about 5% B 2 O 3 and 20% Al 2 O 3 when SiO 2 is absent, not exceeding about 5% B 2 O 3 when Al 2 O 3 is absent, and not exceeding about 10% B 2 O 3 when both SiO 2 and Al 2 O 3 are present, at least about 60% total of MnO 2 + SiO 2 + Al 2 O 3 + B 2 O 3 , 0-30% Nb 2 O 5 , 0-35% La 2 O 3 , 0-10% Ta 2 O 5 , 0-15% BaO, 0-10% SnO 2 , 0-4% ZnO, 0-10% ZrO 2 , 0-20% TiO 2 , 0-5% Fe 2 O 3 , 0-10% NiO, 0-3% Cr 2 O 3 , 0-3% CoO and 0-10% K 2 O; b. melting the batch at a temperature in the range of about 1500°-1600° C. for a time in the range of about 6-16 hours; c. forming the molten glass into a glass article; d. exposing the glass to a temperature in the range of about 600°-1200° C. for a time in the range of about 4-24 hours to obtain crystallization of the glass; and e. exposing the crystallized glass to a temperature in the range of about 500°-1000° C. in a reducing atmosphere for a time in the range of about 1/2-10 hours to develop said exuded surface film comprising said transition metal compounds therein.

Claim 7

A method of providing a glass-ceramic article having an exuded ferromagnetic surface film comprising at least one transition metal compound selected from the group consisting of Mn 3 O 4 , Fe 3 O 4 , MnAl 2 O 4 , NiAl 2 O 4 , NiFe 2 O 4 , MnFe 2 O 4 , MnCr 2 O 4 , MnNb 2 O 6 , NiNb 2 O 6 , Ti 2 Nb 10 O 29 , and Mn 2 Al 2 (SiO 4 ) 2 on at least a portion of the surface thereof which comprises the steps of: a. compounding a batch for a glass composition consisting essentially, in weight percent on the oxide basis as calculated from the batch, of about 10-60% MnO 2 , at least one oxide selected in the indicated proportion from the group consisting of 10-70% SiO 2 , 13-43% Al 2 O 3 , and 0-35% B 2 O 3 , essentially including at least about 5% B 2 O 3 and 20% Al 2 O 3 when SiO 2 is absent, not exceeding about 5% B 2 O 3 when Al 2 O 3 is absent, and not exceeding about 10% B 2 O 3 when both SiO 2 and Al 2 O 3 are present, at least about 60% total of MnO 2 + SiO 2 + Al 2 O 3 + B 2 O 3 , 0-30% Nb 2 O 5 , 0-35% La 2 O 3 , 0-10% Ta 2 O 5 , 0-15% BaO, 0-10% SnO 2 , 0-4% ZnO, 0-10% ZrO 2 , 0-20% TiO 2 , 0-5% Fe 2 O 3 , 0-10% NiO, 0-3% Cr 2 O 3 , 0-3% CoO and 0-10% K 2 O; b. melting the batch at a temperature in the range of about 1500°-1600° C. for a time in the range of about 6-16 hours; c. forming the molten glass into a glass article; d. exposing the glass to a temperature in the range of about 600°-1200° C. for a time in the range of about 4-24 hours to obtain crystallization of the glass; and e. exposing the crystallized glass to a temperature in the range of about 500°-1000° C. in a reducing atmosphere for a time in the range of about 1/2-10 hours to develop said exuded surface film comprising said transition metal compounds therein.