Coated particles of inorganic or metallic materials and processes of producing the same

• US 5,489,449 A
• Filed: 07/18/1994
• Issued: 02/06/1996
• Est. Priority Date: 03/28/1990
• Status: Expired due to Term

• Current Assignee: Kaoru Umeya, Nisshin Seifun Group Incorporated
• Original Assignee: Kaoru Umeya, Nisshin Flour Milling Incorporated (Nisshin Seifun Group Incorporated)
• Inventors: Umeya, Kaoru, Akiyama, Satoshi, Fuyuki, Tadashi, Yamada, Yukiyoshi, Kuroda, Eisuke
• Primary Examiner(s): PADGETT, MARIANNE L
• Application Number:
  US08/276,496
• Time in Patent Office: 568 Days
• Field of Search: 428/403, 428/570, 428/404, 428/901, 428/934, 428/936, 428/938, 427/124, 427/126.1, 427/126.2, 427/126.3, 427/213, 427/215, 427/216, 427/217, 427/446, 427/450, 427/451, 427/452, 427/453, 427/454, 427/455, 427/456, 427/562 , 427/563, 427/564
• US Class Current: 427/450
• CPC Class Codes: B01J 8/42 with fluidised bed subjected to electric current or to radiations this sub-group includes the fluidised bed subjected to electric or magnetic fields
• CPC Class Codes: B22F 1/18 Non-metallic particles coated with metal
• CPC Class Codes: C04B 35/581 based on aluminium nitride
• CPC Class Codes: C04B 35/584 based on silicon nitride
• CPC Class Codes: C23C 16/4417 Methods specially adapted for coating powder
• CPC Class Codes: C23C 16/442 using fluidised bed process
• CPC Class Codes: C23C 16/513 using plasma jets

Abstract

A particle of an inorganic or metallic material which is coated on the surface with ultrafines of an inorganic or metallic material. The coated particle is produced by introducing the particles of the inorganic or metallic material to be coated into a stream carrying the ultrafines of the inorganic or metallic material formed in a vapor phase and bringing the particles to be coated into contact with said ultrafines in a fluidized state. The coated particles are used for the production of a sintered product.

Claims

1. A process of producing sinterable coated particles of inorganic material in which core particles of a first inorganic material are coated on their surfaces with a powder of ultrafines having a particle size of less than 0.5 μ

m of a second inorganic material chemically bonded to the core particles, which comprises generating a powder of ultrafines of the second inorganic material in a vapor phase by a plasma flame in a gas in an ultrafines powder generating zone from a feed supplying material from which the ultrafines are generated to produce the powder of ultrafines in an activated state for chemical combination with the material of the core particles;

thereafter introducing said powder of ultrafines in the activated state in the gas of the plasma flame and the core particles of the first inorganic material, while being carried by a carrier gas, into a particle contacting zone in which the core particles are brought into contact with the powder of the ultrafines while the ultrafines are in the activated state, thus having the powder of the ultrafines chemically bonded to the core particles in a gas stream comprising the said carrier gas and the gas of the plasma flame; and

recovering the sinterable coated particles from the gas stream.

2. The process of claim 1, wherein the core particles and the ultrafines are composed of the same material.

3. The process of claim 1, wherein the core particles and the ultrafines are composed of different materials.

4. The process of claim 1, wherein the core particles are of an average particle size of 0.1 to 100 μ

m.

5. The process of claim 1, wherein the ultrafines are of an average particle size of 0.005 to 0.5 μ

m.

6. The process of claim 1, wherein the core particles and the ultrafines are composed of ceramic materials.

7. The process of claim 1, wherein the core particles are composed of ceramic material and the ultrafines are composed of a metal.

8. The process of claim 1, wherein the ultrafines are composed of yttrium oxide and the core particles are composed of silicon nitride.

9. The process of claim 1, wherein the ultrafines are composed of cobalt and the core particles are diamond particles.

10. The process of claim 1, wherein the ultrafines are composed of carbon and the core particles are diamond particles.

11. The process of claim 1 wherein the ultrafines are composed of titanium and the core particles are diamond particles.