Translucent ceramic whiteware products

Claim 2

A vitrified, translucent, low-expansion ceramic body suitable for glazing with a glaze, the ceramic body, consisting essentially of: a semicrystalline, non-porous, whiteware ceramic body having an oxide analysis consisting essentially of 51.5 to 58 parts by weight SiO 2 , 28 to 36 parts by weight Al.sub. 2 O 3 , 10 to 17 parts by weight MgO, and 4 to 10 parts by weight of oxides selected from Na 2 O, K 2 O, CaO, BaO, SrO, PbO, and ZnO, wherein the parts by weight are based on SiO 2 + Al.sub. 2 O 3 + MgO = 100 weight parts; said ceramic body having a coefficient of expansion less than 50 × 10.sup. -7 cm./cm./°C; said ceramic body having a crystalline phase consisting of cordierite; said ceramic body having an Fe 2 O 3 + TiO 2 content of less than 1% by weight; said ceramic body being substantially free of lithia (Li 2 O); and said ceramic body having a light transmission of at least about 0.9% per 0.1 inch thickness.

Claim 3

The vitrified, translucent, low-expansion ceramic body of claim 1 wherein the ceramic body has an oxide analysis consisting essentially of 53 to 57 parts by weight of SiO 2 , 30 to 34 parts by weight of Al.sub. 2 O 3 , 12.5 to 15 parts by weight of MgO, and 4 to 8 parts by weight of said other oxides.

Claim 4

In a process for forming a translucent, semicrystalline, nonporous, low-expansion, whiteware ceramic body suitable for glazing in a subsequent glazing process, said ceramic body having a crystalline phase consisting of cordierite and having a light transmission of at least about 0.9% per 0.1 inch thickness, the batch materials being fired at temperature ranges from about 2000°F to 2400°F, the improvement in the process comprising: compounding batch particulate materials having an average particle size of less than 44 microns, said batch materials being substantially free of lithia (Li 2 O) and containing by weight less than 1% Fe 2 O 3 + TiO 2 , said batch materials consisting essentially of: (a) 20 to 40 weight parts of talc containing less than 1% Fe 2 O 3 + TiO 2 ; (b) 24 to 40 weight parts of clay consisting of a mixture of kaolin clay and ball clay wherein said mixture of clay contains 80% to 100% kaolin clay and less than 1% Fe 2 O 3 + TiO 2 ; (c) 8 to 15 weight parts alumina; and (d) 12 to 40 weight parts of other oxide-producing materials selected from alkaline earth aluminosilicates, alkali aluminosilicates, and oxides of K 2 O, Na 2 O, CaO, SrO, BaO, PbO, and ZnO; wherein said other oxide-producing materials have a composition within the range of 0% - 25% MgO, 10% - 25% Al.sub.2 O.sub.3, 50% - 75% SiO.sub.2, wherein the MgO + Al.sub. 2 O 3 + SiO 2 comprise at least 80% of said other oxide-producing materials, and 0% to 20% of said other oxide producing materials have a composition within the range of 0% - 16% K.sub.2 O, Na.sub.2 O, 0% - 20% CaO, SrO, BaO, 0% - 3% PbO, ZnO; forming from said batch materials a green body having a vitrification range of at least 100°F; and firing said green body to form a translucent ceramic body having a light transmission of 0.9% per 0.1 inch thickness and a composition consisting essentially of 51.5 to 58 parts by weight silica, 28 to 36 parts by weight Al.sub. 2 O 3 , 10 to 17 parts by weight MgO, and 4 to 10 parts by weight oxides selected from Na 2 O, K 2 O, CaO, BaO, SrO, PbO, and ZnO wherein the parts by weight are based on SiO 2 + Al.sub. 2 O 3 + MgO = 100 weight parts.

Claim 5

In a process for forming a translucent, semicrystalline, nonporous, low-expansion, whiteware ceramic body suitable for glazing in a subsequent glazing process, said ceramic body having a crystalline phase consisting of cordierite and having a light transmission of at least about 0.9% per 0.1 inch thickness, the batch materials being fired at temperature ranges from about 2000°F to 2400°F, the improvement in the process comprising: compounding batch particulate materials having an average particle size of less than 44 microns, said batch materials being substantially free of lithia (Li 2 O) and containing by weight less than 1% Fe 2 O 3 + TiO 2 , said batch materials consisting essentially of: (a) 20 to 40 weight parts of talc containing less than 1% Fe 2 O 3 + TiO 2 ; (b) 24 to 40 weight parts of clay consisting of a mixture of kaolin clay and ball clay wherein said mixture of clay contains 80% to 100% kaolin clay and less than 1% Fe 2 O 3 + TiO 2 ; (c) 8 to 15 weight parts alumina; and (d) 12 to 40 weight parts of other oxide-producing materials selected from alkaline earth aluminosilicates, alkali aluminosilicates, and oxides of K 2 O, Na 2 O, CaO, SrO, BaO, PbO, and ZnO; wherein said other oxide-producing materials have a composition within the range of 0% - 25% MgO, 10% - 25% Al.sub.2 O.sub.3, 50% - 75% SiO.sub.2, wherein the MgO + Al.sub. 2 O 3 + SiO 2 comprise at least 80% of said other oxide-producing materials, and 0% to 20% of said other oxide producing materials have a composition within the range of 0% - 16% K.sub.2 O, Na.sub.2 O, 0% - 20% CaO, SrO, BaO, 0% - 3% PbO, ZnO; forming from said batch materials a green body having a vitrification range of at least 100°F; and firing said green body to form a translucent ceramic body having a light transmission of 0.9% per 0.1 inch thickness and a composition consisting essentially of 51.5 to 58 parts by weight silica, 28 to 36 parts by weight Al.sub. 2 O 3 , 10 to 17 parts by weight MgO, and 4 to 10 parts by weight oxides selected from Na 2 O, K 2 O, CaO, BaO, SrO, PbO, and ZnO wherein the parts by weight are based on SiO 2 + Al.sub. 2 O 3 + MgO = 100 weight parts.