Ceramic utensil for microwave cooking

A cooking utensil for preparing food in a microwave oven comprising:

• an open top ceramic vessel for receiving foodstuff to be cooked, said vessel having bottom and sidewalls and an upwardly facing lip at the upper edge of said sidewalls;
• a ceramic cover for closing the open top of said vessel, said cover having a lower surface which further comprises a downwardly facing lip for mated engagement with the upwardly facing lip on said vessel;
• said vessel and said cover being microwave transparent and essentially nonconductive and having interior surfaces substantially free of sharp comers, said interior surfaces defining an interior portion of the cooking utensil, and a glaze bonded on at least the interior surfaces of said vessel and said cover including the mating lips thereon;
• said glaze comprising a dielectric matrix and semiconductive particles distributed throughout said matrix;
• the percent loading of the semiconductive particles in the matrix being sufficient to cause a portion of the microwave energy in the oven to be reflected away from the interior portion of the utensil, a portion of the microwave energy to be transmitted to the interior portion of the utensil and a portion of the microwave energy to be converted to high temperature thermal energy by the semiconductive particles in the glaze for causing thermal energy to be transferred from the interior surfaces of said vessel and said cover to an outer surface of the foodstuff by convection, conduction and radiant heat transfer;
• and
• said glaze particularly shielding the foodstuff from absorption of microwave energy and causing the amount of heat transferred to the outer surface of the foodstuff as thermal energy from the interior surfaces of said vessel and said cover to be increased relative to the amount of heat that is generated by the microwave energy absorbed within the foodstuff.

A method of preparing foods in a microwave oven comprising the steps of:

• placing the food in a microwave transparent, nonconductive ceramic utensil comprised of an open top food receiving vessel and a cover for the open top of the vessel said vessel and cover further having interior surfaces and exterior surfaces;
• exposing the ceramic utensil to microwave energy in a microwave oven;
• partially shielding the food in the utensil from the microwave energy in the oven;
• converting a portion of the microwave energy present in the oven to thermal energy concentrated on the interior surfaces of the vessel and the cover;
• the shielding and converting steps being performed by applying a semiconductive glaze to at least the interior surfaces of the vessel and the cover prior to placing the food in the utensil and exposing the utensil to microwave energy;
• the semiconductive glaze being comprised of a dielectric matrix and semiconductive particles distributed throughout the matrix in sufficient proportion to perform the shielding and converting steps when the food containing utensil is exposed to microwave energy;
• and
• cooking the food in the utensil partially by absorption of microwave energy within the food and primarily by transfer of thermal energy from the interior surfaces of the vessel and the cover to the exterior surfaces of the food.

A method of making cooking utensils for use in preparing foods in microwave ovens comprising the steps of:

• forming from a microwave transparent, nonconductive ceramic material an open top food receiving vessel and a mating cover for the open top of the vessel, said vessel and cover having interior and exterior surfaces;
• applying to at least the interior surfaces of the vessel and the cover a glaze comprised of a dielectric matrix and semiconductive particles distributed throughout the matrix, the percent loading of the semiconductive particles in the matrix being sufficient to partially shield the interior of the utensil from microwave energy and to partially absorb microwave energy for conversion to thermal energy at the interior surfaces of the utensil;
• and
• sintering the glaze to bond said glaze to the interior surfaces of the vessel and the cover.