Dual coat ceramic layer prepared by single firing
AssigneeFerro Corporation
InventorRichard G. Rion
Life of this patent
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Abstract
A process and resulting product are disclosed characterized by superimposing two layers of essentially dry, differing frit compositions onto a substrate and then firing only once to form a dual coat coherent ceramic layer. The composition of the two frits is such that the first or base coat fuses and stabilizes during the firing operation at temperatures below that at which the second or cover coat fuses and stabilizes. Desirably, the first layer forms an amorphous glass adherent to the substrate that is predominantly an alkaline oxide borosilicate glass and preferably an alkaline borofluorosilicate glass.
Claims16
A process for applying a dual coat ceramic layer to a substrate in a single firing operation, comprising applying to the substrate a first coat of an essentially dry powder of a first frit composition adapted to form a glass adherent to said substrate, applying to said first coat a second coat of an essentially dry powder of a second frit composition normally not adapted as a glass to adhere to said substrate, subjecting said substrate and coats to a single firing operation, initially fusing and completely stabilizing said first frit composition within a temperature range below that at which said second frit composition first fuses and stabilizes, then fusing and stabilizing said second frit composition within a temperature range higher than said first temperature range, whereby said first coat reaches a state of neither tension nor compression at a temperature below that at which said second coat first reaches a state of neither tension nor compression, and finally cooling to form a coherent ceramic layer of two substantially continuous coats on said substrate from the two frit compositions.
A process for applying a dual coat ceramic layer to a substrate in a single firing operation, comprising applying to the substrate a first coat of an essentially dry powder of a first frit composition adapted to form a glass adherent to said substrate, applying to said first coat a second coat of an essentially dry powder of a second frit composition normally not adapted as a glass to adhere to said substrate, subjecting said substrate and coats to a single firing operation, sequentially fusing and completely stabilizing in turn said first frit composition within a first temperature range and then said second frit composition at a second and higher temperature range, and then cooling to form a dual coat coherent ceramic layer on said substrate from the two frit compositions.
Dependencies are inferred from the claim text.