Oven rack having an integral lubricious, dry porcelain surface

Abstract

A lubricious porcelain coated steel wire oven rack. The preferred coated steel wire oven rack includes a plurality of elongated steel wire members joined together to form an oven rack having an outer surface. The plurality of elongated steel wire members are made from a cold drawn steel rod material containing from about 80 to about 99.9% by weight of iron, up to about 0.08% by weight of carbon and from about 0.001 to about 0.2% by weight of a carbon stabilizing transition metal, preferably selected from the group consisting of Vanadium, Tantalum, Titanium and Niobium. In a preferred embodiment, the porcelain surface of the oven rack includes a dry lubricant selected from carbon; graphite; boron nitride; cubic boron nitride; molybdenum (IV) sulfide; molybdenum disulfide; molybdenum sulfide; molybdenum (IV) selenide; molybdenum selenide; tungsten (IV) sulfide; tungsten disulfide; tungsten sulfide; silicon nitride (Si3N4); TiN; TiC; TiCN; TiO2; TiAlN; CrN; SiC; diamond-like carbon; tungsten carbide (WC); zirconium oxide (ZrO2); zirconium oxide and 0.1 to 40 weight % aluminum oxide; alumina-zirconia; antimony; antimony oxide; antimony trioxide; and mixtures thereof.

Description

FIELD OF THE DISCLOSURE [0001] The present disclosure is directed to glass, ceramic or porcelain coated metal products wherein the porcelain coating has a lubricious surface such that repeated sliding contact against another porcelain surface does not cause noticeable deterioration in the form of marring, chipping or flaking of the porcelain of either porcelain surface. In the preferred embodiment, these products are porcelain-enameled steel oven racks that are subjected to temperatures above 500° F., usually above 900° F., as in self-cleaning, pyrolytic ovens, and the metal is steel wire that has the composition disclosed in this assignee's U.S. Pat. Nos. 6,837,235 and 6,915,552, both hereby incorporated by reference. Alternately, the product can be formed of cast iron, such as a burner grate. The preferred combination of the steel wire together with the lubricious porcelain coating provides oven racks which do not discolor during cooking or during self-cleaning cycles when the ove...

AI Technical Summary

Benefits of technology

The patent describes a lubricious oven rack made of coated steel wire that is designed to be placed in an oven. The steel wire is coated with a special glass material that has a lubricious outer surface, which prevents chipping of the glass when the rack is heated or cooled. The glass material is applied to the steel wire using a two-step process, where the glass is first coated onto a porcelain material before being applied to the steel wire. The coated steel wire is made from a special steel rod that has reduced carbon content, which prevents the release of hydrogen gas when the wire is heated or cooled. The reduced carbon content also prevents the formation of cracks, spalls, and chipping on the porcelain surface of the rack. The coated steel wire is designed to be durable and easy to clean.

Problems solved by technology

In addition to the hydrogen out-gassing problem experienced at high temperatures with porcelain-encapsulated steel oven racks, another very significant problem has more recently been discovered during the manufacture, testing and use of the porcelain-coated oven racks.

It has been found that the porcelain can deteriorate by marring, flaking or chipping off of the porcelain material from the oven racks as a result of the normal periodic sliding contact between the oven rack porcelain surface and a contacting porcelain wall surface of the oven cavity.

That is, over the 13 to 15 year normal life expectancy of an oven, the repeated sliding porcelain-to-porcelain contact upon insertion and removal of the porcelain-coated oven racks, particularly when the oven racks are supporting a relatively heavy cooking load, can cause unwanted abrasion, chipping and squeaking of the sliding porcelain surface (of one type) against and across a porcelain surface (of the same or another type) on the oven wall.

Prior to this assignee's out-gassing solution, as described in the '235 and '522 patents, commercially satisfactory porcelain-coated oven racks to be used in self-cleaning pyrolytic ovens were non-existent so that assistance in attempting to solve the porcelain-to-porcelain abrasion and flaking problem in porcelain materials that are regularly subjected to temperatures above 900° F. was not forthcoming from the prior art.

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