Inclusion pigments of zirconium silicate with included chromic oxide, a process for the preparation and use thereof

A process for preparing a brilliant light green inclusion pigment having zirconium silicate as a casing component and an inorganic oxide having a fine particle size as a discrete, included colored compound, comprising:

• fusing a mixture of a zirconium dioxide source, a silicon dioxide source, an inorganic oxide having a fine particle size to be included and a mineralizator, at a temperature in the range of 800.degree. C. to 1300.degree. C., for a period of from 0.5 to 8 hours, wherein the inorganic oxide is chromic oxide having a D.sub.50 average particle size value in the range of 0.1 and 3.0 .mu.m, wherein the pigment has a color value, as measured in the CIE-Lab-system, in the range of L=30 to 35, a=-15 to -17 and b=13 to 16, measured with a 5% by weight coloration in a transparent enamel and by burning or firing at 1060.degree. C.

A process for forming a colored ceramic, comprising:

• providing a ceramic with an inclusion pigment, said inclusion pigment having zirconium silicate as a casing component and an inorganic oxide having a fine particle size as a discrete, included colored compound, wherein the inorganic oxide is chromic oxide having a D.sub.50 average particle size value in the range of 0.1 to 3.0 .mu.m, to thereby color the ceramic with a brilliant, light green color, wherein the pigment has a color value, as measured in the CIE-Lab-system, in the range of L=30 to 35, a=-15 to -17 and b=13 to 16, measured with a 5% by weight coloration in a transparent enamel and by burning or firing at 1060.degree. C.

A brilliant light green inclusion pigment comprising:

• zirconium silicate as a casing component and an inorganic oxide having a fine particle size as a discrete, included colored compound, wherein the inorganic oxide is chromic oxide having a D.sub.50 average particle size value in the range of 0.1 to 3.0 .mu.m, wherein the inclusion pigment is produced according to a process which consists essentially of:
• fusing a mixture of a zirconium dioxide source, a silicon dioxide source, an inorganic oxide having a fine particle size to be included and a mineralizator, at a temperature in the range of 800.degree. C. to 1300.degree. C., for a period of from 0.5 to 8 hours, wherein the inorganic oxide is chromic oxide having a D.sub.50 average particle size value in the range of 0.1 and 3.0 .mu.m.

A process for preparing an inclusion pigment having zirconium silicate as a casing component and an inorganic oxide having a fine particle size as a discrete, included colored compound, consisting essentially of:

• fusing a mixture of a zirconium dioxide source, a silicon dioxide source, an inorganic oxide having a fine particle size to be included and a mineralizator, at a temperature in the range of 800.degree. C. to 1300.degree. C., for a period of from 0.5 to 8 hours, wherein the inorganic oxide is chromic oxide having a D.sub.50 average particle size value in the range of 0.1 and 3.0 .mu.m.