Bright noble metal preparation
View Patent ↗A bright noble metal preparation for firing on ceramic/porcelain surfaces at a minimum temperature of 900° C. The preparation has at least one organic noble metal compound including at least one of an organic gold, platinum, silver, and palladium compound, at least one flux that consists of organometallic compounds including Cr in the form of at least one organic compound, such that a Cr content is 0.01 to 1.0 mole per mole of noble metal, and at least one vehicle. The bright noble metal preparation is rhodium-free and has a noble metal content of 6 to 20 wt. %, based on the preparation.
1. A process for producing a decorative coating on a surface of a porcelain or ceramic article comprising the steps of:
preparing a rhodium-free noble metal preparation of at least one organic noble metal compound including an organic gold compound, at least one flux that consists of organometallic compounds, including Cr in the form of at least one organic compound, such that a Cr content is 0.01 to 1.0 mole per mole of noble metal, and at least one vehicle, wherein the bright noble metal preparation has a noble metal content of 6 to 20 wt. % based on the preparation and at least one other element selected from the group consisting of Si and Ni in the form of organic compounds, such that a total content of Si, Cr, and Ni is 0.2 to 2.0 moles per mole of noble metal;
applying the preparation on the surface of porcelain or a tile; and
firing the noble metal preparation at a temperature of 900° C. to 1300° C. to produce a bright decorative coating on the surface of the ceramic or porcelain article.
2. The process in accordance with claim 1 , wherein the Cr content is 0.05 to 0.4 mole per mole of noble metal.
3. The process in accordance with claim 1 , wherein the total content of Si, Cr, and Ni is 0.25 to 1.50 mole per mole of noble metal.
4. The process in accordance with claim 1 , wherein the preparing step includes preparing a noble metal preparation further including at least one other element selected from the group consisting of Cu, Co, Sn, Zr, and Bi in the form of organic compounds, such that a content of Cu, Co, Sn, Zr, and Bi is up to 0.3 mole each per mole of noble metal.
5. The process in accordance with claim 1 , wherein the preparing step includes preparing a noble metal preparation further including at least one other element selected from the group consisting of B, Al, Ca, Ti, V, Mn, Fe, Zn, Ge, Pb, Sr, Mo, Ru, In, Ba, Ta, W, Os, Ir, and Ce in the form of organic compounds, such that a content of B, Al, Ca, Ti, V, Mn, Fe, Zn, Ge, Pb, Sr, Mo, Ru, In, Ba, Ta, W, Os, Ir, and Ce is up to 0.3 mole each per mole of noble metal.
6. The process in accordance with claim 1 , wherein the noble metal content is 6 to 14 wt. % based on the preparation.