Process for producing hollow spherical particles and sponge-like particles composed therefrom

Claim 2

A process for making hollow spherical particles, comprising the steps of: (a) providing metallized lightweight spherical bodies from cores of a foamed polymer with a metallic coating of a thickness of 5 to 20 microns; (b) coating said metallized lightweight spherical bodies with a dispersion of at least one particulate material selected from the group which consists of metals, metal oxides, ceramics and refractories to a dispersion coating thickness of 15 to 500 microns; (c) drying the dispersion coating on said metallized lightweight spherical bodies to form a dry layer of said material thereon; (d) heating said metallized lightweight spherical bodies with said dry layer of said material thereon to a temperature of about 400° C. to pyrolyze said polymer cores and form hollow bodies essentially consisting of said metallic coatings and said dry layers of said material thereon; and (e) subjecting said hollow bodies essentially consisting of said metallic coatings and said dry layers of said material thereon to a sintering temperature of 900° C. to 1400° C. for a period sufficient to sinter the material of the respective layer and the respective layer to the respective metallic coating, thereby forming hollow spherical particles.

Claim 3

The process defined in claim 1 wherein, for step (b), an organic binder capable of thermal decomposition without residue is incorporated in said dispersion.

Claim 4

The process defined in claim 1 wherein, for step (b), said dispersion is formed from at least one particulate metal selected from the group which consists of Fe, Cu, Ni, Cr, W and Ta, or at least one oxide thereof.

Claim 5

The process defined in claim 1 wherein, for step (b), said dispersion is formed from at least one ceramic or refractory.

Claim 6

The process defined in claim 1 wherein, for step (b), said dispersion is formed from particles of said material having a particle size of about 0.1 to 500 microns.

Claim 7

The process defined in claim 1 wherein, for steps (d) and (e), said metallized lightweight spherical bodies with said dry layer of said material thereon are vibrated into a mold and pyrolyzed at a temperature of about 400° C. and the resulting hollow bodies essentially consisting of said metallic coatings and said dry layers of said material thereon are then sintered by being heated to a temperature of 900° C. to 1400° C.

Claim 8

The process defined in claim 1 wherein said material consists of a ceramic or refractory, further comprising the step of: (f) treating the particles of step (e) with acid to remove the metal of said metallic coatings therefrom.

Claim 9

A process for making a molded article, comprising the steps of: (a) providing metallized lightweight spherical bodies from cores of a foamed polymer with a metallic coating of a thickness of 5 to 20 microns; (b) coating said metallized lightweight spherical bodies with a dispersion of at least one particulate material selected from the group which consists of metals, metal oxides, ceramics and refractories to a dispersion coating thickness of 15 to 500 microns; (c) drying the dispersion coating on said metallized lightweight spherical bodies to form a dry layer of said material thereon; (d) vibrating the metallized lightweight spherical bodies with said dry layers of said material thereon into a mold having a shape corresponding to that of said article; (e) heating said metallized lightweight spherical bodies with said dry layer of said material thereon in said mold to a temperature of about 400° C. to pyrolyze said polymer cores and form hollow bodies essentially consisting of said metallic coatings and said dry layers of said material thereon; and (f) subjecting said hollow bodies essentially consisting of said metallic coatings and said dry layers of said material thereon in said mold to a sintering temperature of 900° C. to 1400° C. for a period sufficient to sinter the material of the respective layer and the respective layer to the respective metallic coating, thereby forming hollow spherical particles and to sinter said hollow spherical particles together into said article.

Claim 10

A process for making a molded article, comprising the steps of: (a) providing metallized lightweight spherical bodies from cores of a foamed polymer with a metallic coating of a thickness of 5 to 20 microns; (b) coating said metallized lightweight spherical bodies with a dispersion of at least one particulate material selected from the group which consists of metals, metal oxides, ceramics and refractories to a dispersion coating thickness of 15 to 500 microns; (c) drying the dispersion coating on said metallized lightweight spherical bodies to form a dry layer of said material thereon; (d) vibrating the metallized lightweight spherical bodies with said dry layers of said material thereon into a mold having a shape corresponding to that of said article; (e) heating said metallized lightweight spherical bodies with said dry layer of said material thereon in said mold to a temperature of about 400° C. to pyrolyze said polymer cores and form hollow bodies essentially consisting of said metallic coatings and said dry layers of said material thereon; and (f) subjecting said hollow bodies essentially consisting of said metallic coatings and said dry layers of said material thereon in said mold to a sintering temperature of 900° C. to 1400° C. for a period sufficient to sinter the material of the respective layer and the respective layer to the respective metallic coating, thereby forming hollow spherical particles and to sinter said hollow spherical particles together into said article.

Claim 11

Hollow spherical particles as made by the process of claim 1.

Claim 12

The article made by the process of claim 1.

Claim 13

An article consisting essentially of hollow spherical particles sintered together and having an open sponge structure, each of said particles consisting of a layer of sintered particulate material selected from the group which consists of metals, metal oxides, ceramics and refractories in a thickness of 15 to 500 microns bonded to the exterior of a metallic shell.

Claim 14

An article consisting essentially of hollow spherical particles sintered together and having an open sponge structure, each of said particles consisting of a layer of sintered particulate material selected from the group which consists of metals, metal oxides, ceramics and refractories in a thickness of 15 to 500 microns bonded to the exterior of a metallic shell.

Claim 15

The article defined in claim 11 wherein said shell has a thickness of 5 to 20 microns.

Claim 16

The article defined in claim 12 wherein said material consists of at least one particulate metal selected from the group which consists of Fe, Cu, Ni, Cr, W and Ta, or at least one oxide thereof.

Claim 17

The article defined in claim 12 wherein said material consists of at least one ceramic or refractory.

Claim 18

The article defined in claim 12 wherein said material consists of particles of said material having a particle size of about 0.1 to 500 microns.