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US 4,084,975 AGranted
Volatilizable frit composition forming oxidation-inhibiting vapors
AssigneeFerro Corporation
InventorWilliam D. Faust
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AssigneeFerro Corporation
InventorWilliam D. Faust
Estimating the term…
A frit composition is disclosed adapted to be applied to a metal substrate containing iron and fired to form a ceramic coat. The frit composition comprises a primary devitrifiable frit adapted to fuse at a firing temperature and upon cooling form devitrified particles; and a secondary frit containing a volatilizable metal oxide adapted to form at a firing temperature substantially an amorphous glass and precipitate crystals of the volatilizable metal oxide. The crystals at least partially volatilize at the firing temperature to provide protective vapors effective to inhibit oxidation of the substrate. Upon cooling, the amorphous glass of the secondary frit bonds the devitrified particles of the primary frit one to another. Preferably, the devitrified particles of the primary frit provide a porous ceramic coat such as on a surface of a self-cleaning cooking device exposed to cooking residues. In this case, the primary frit may also contain an oxidation catalyst.
A frit composition adapted to be applied to a metal substrate containing iron and fired to form a ceramic coat, said frit composition comprising (a) in major amount a primary devitrifiable frit composition adapted to fuse at a firing temperature and upon cooling form devitrified particles, and (b) in minor amount a secondary frit composition containing a volatilizable metal oxide adapted to form at a firing temperature a substantially amorphous glass and precipitate crystals of said volatilizable metal oxide partially to volatilize said precipitated crystals at said firing temperature, thereby to provide protective vapors effective to inhibit oxidation of said substrate, and upon cooling to form an amorphous bond adhering said devitrified particles of the primary frit composition one to another, said volatilizable metal oxide being selected from the oxides of antimony, tin, vanadium, molybdenum, lead, arsenic, and mixtures thereof, the combination of said devitrifiable primary and amorphous secondary frit compositions providing a balanced, controlled release of the metallizable metal oxide at the time of firing to extend the protection afforded by the volatilizable metal oxide over a period of time.
In a process for forming a ceramic coat over a metal substrate containing iron by applying a frit composition thereover and firing, the improvement of inhibiting oxidation of said substrate during the firing by using combined frit compositions comprising (a) in a major amount a primary devitrifiable frit composition adapted to fuse at a firing temperature and upon cooling form devitrified particles, and (b) in minor amount a secondary frit composition adapted to form at a firing temperature a substantially amorphous glass, firing said primary and secondary frit compositions, forming an amorphous glass from said secondary composition, precipitating crystals of said volatilizable metal oxide from said amorphous glass, at least partially volatilizing said crystals to provide protective vapors effective to inhibit oxidation of said substrate, forming devitrified particles from said primary composition upon cooling, and using said amorphous glass to bond said devitrified particles one to another, said volatilizable metal oxide being selected from the oxides of antimony, tin, vanadium, molybdenum, lead, arsenic, and mixtures thereof, the combination of said devitrifiable primary and amorphous secondary frit compositions providing a balance, controlled release of the volatilizable metal oxide at the time of said firing to extend the protection afforded by the volatilizable metal oxide over a period of time.
Dependencies are inferred from the claim text.