A method of making a refractory article is provided. The method includes: a) mixing a binder system, a refractory charge, and a second colloidal binder to form an aqueous slurry; b) casting the aqueous slurry into a mold; c) subjecting the mold containing the aqueous slurry to a temperature that is lower than a slurry casting temperature for a time sufficient to form a green strength article; and d) firing the green strength article at a temperature of at least 450° C. for a time sufficient to achieve thermal homogeneity, thereby forming a refractory article. Refractory articles made in accordance with the method have a unique combination of pore structure and mechanical properties.

A method of making a refractory article is provided. The method includes: a) mixing a binder system, a refractory charge, and a second colloidal binder to form an aqueous slurry; b) casting the aqueous slurry into a mold; c) subjecting the mold containing the aqueous slurry to a temperature that is lower than a slurry casting temperature for a time sufficient to form a green strength article; and d) firing the green strength article at a temperature of at least 450° C. for a time sufficient to achieve thermal homogeneity, thereby forming a refractory article. Refractory articles made in accordance with the method have a unique combination of pore structure and mechanical properties.

A method and apparatus for forming variable density ceramic structures, where the method includes: obtaining a ceramic powder having an ultrafine particle size; mixing the ceramic powder into a suspension fluid thus forming a ceramic suspension; providing a mold configured to retain the ceramic suspension; providing a plurality of electrodes about the mold; applying an alternating voltage to the electrodes thus forming alternating electric currents through the suspension thus causing accumulation of ceramic particles on at least one of the electrodes; reducing the temperature of the suspension thus inducing the formation of ice crystals therein necessary for ice-templating; freeze drying the frozen suspension into a porous state; and sintering the ceramic particles into a solid architecture retaining a common final structure with the ceramic particles in the porous state.

A method and apparatus for forming variable density ceramic structures, where the method includes: obtaining a ceramic powder having an ultrafine particle size; mixing the ceramic powder into a suspension fluid thus forming a ceramic suspension; providing a mold configured to retain the ceramic suspension; providing a plurality of electrodes about the mold; applying an alternating voltage to the electrodes thus forming alternating electric currents through the suspension thus causing accumulation of ceramic particles on at least one of the electrodes; reducing the temperature of the suspension thus inducing the formation of ice crystals therein necessary for ice-templating; freeze drying the frozen suspension into a porous state; and sintering the ceramic particles into a solid architecture retaining a common final structure with the ceramic particles in the porous state.

An optical converter is provided that has both a stable colour even at highest luminous powers and a high luminous efficiency. The optical converter includes a ceramic element that is fluorescent so that light of a first wavelength is absorbed in the ceramic element and fluorescent having longer wavelength light is emitted. The ceramic element includes pores spatially irregularly distributed within the ceramic element. The distribution of the pores within the ceramic element is inhomogeneous so that the radial distribution function of the pore locations deviates from unity and has a maximum at a characteristic distance, the maximum having a value of at least 1.2.

An optical converter is provided that has both a stable colour even at highest luminous powers and a high luminous efficiency. The optical converter includes a ceramic element that is fluorescent so that light of a first wavelength is absorbed in the ceramic element and fluorescent having longer wavelength light is emitted. The ceramic element includes pores spatially irregularly distributed within the ceramic element. The distribution of the pores within the ceramic element is inhomogeneous so that the radial distribution function of the pore locations deviates from unity and has a maximum at a characteristic distance, the maximum having a value of at least 1.2.

The purpose of the present invention is to provide a zirconia-based porous body which can be pulverized in a relatively short time and in which performance deterioration caused by pulverization is suppressed. The present invention pertains to a zirconia-based porous body in which the total pore volume is at least 1.0 ml/g, the pore volume of pores having a diameter of 20-100 nm (exclusive of 100) is at most 0.3 ml/g, and the pore volume of pores having a diameter of 100-1000 nm is at least 0.5 ml/g.

The purpose of the present invention is to provide a zirconia-based porous body which can be pulverized in a relatively short time and in which performance deterioration caused by pulverization is suppressed. The present invention pertains to a zirconia-based porous body in which the total pore volume is at least 1.0 ml/g, the pore volume of pores having a diameter of 20-100 nm (exclusive of 100) is at most 0.3 ml/g, and the pore volume of pores having a diameter of 100-1000 nm is at least 0.5 ml/g.

A method of making a refractory article is provided. The method includes: a) mixing a binder system, a refractory charge, and a second colloidal binder to form an aqueous slurry; b) casting the aqueous slurry into a mold; c) subjecting the mold containing the aqueous slurry to a temperature that is lower than a slurry casting temperature for a time sufficient to form a green strength article; and d) firing the green strength article at a temperature of at least 450° C. for a time sufficient to achieve thermal homogeneity, thereby forming a refractory article. Refractory articles made in accordance with the method have a unique combination of pore structure and mechanical properties.

A method of making a refractory article is provided. The method includes: a) mixing a binder system, a refractory charge, and a second colloidal binder to form an aqueous slurry; b) casting the aqueous slurry into a mold; c) subjecting the mold containing the aqueous slurry to a temperature that is lower than a slurry casting temperature for a time sufficient to form a green strength article; and d) firing the green strength article at a temperature of at least 450° C. for a time sufficient to achieve thermal homogeneity, thereby forming a refractory article. Refractory articles made in accordance with the method have a unique combination of pore structure and mechanical properties.