Silicon alloy, alloy powder thereof, manufacturing apparatus, manufacturing process and sintered alloy thereof

Abstract

A controlled combustion synthesis apparatus comprises an ignition system, a pressure sensor for detecting internal pressure, a nitrogen supply, a gas pressure control valve for feeding nitrogen and exhausting reaction gas, means for detecting the internal temperature of the reaction container, a water cooled jacket, and a cooling plate. A temperature control system controls the temperature of the reaction container by controlling the flow of cooling water supplied to the jacket and the cooling plate in response to the detected temperature. By combustion synthesizing, while controlling the internal pressure and temperature, the apparatus can synthesize a silicon alloy including 30-70 wt. % silicon, 10-45 wt. % nitrogen, 1-40 wt. % aluminum, and 1-40 wt % oxygen.

1 . A silicon alloy including 30-70 weight % silicon, 10-45 weight % nitrogen, 1-40 weight % aluminum and 1-40 weight % oxygen. 
     
     
         2 . A silicon alloy powder, the grains of which are composed of the silicon alloy of  claim 1 , and have diameters less than or equal to 1 micron. 
     
     
         3 . A silicon alloy powder according to  claim 2 , including a sintering additive comprising 0.1-10% by weight of an oxide of at least one element from the group consisting of yttrium, ytterbium, aluminum and zirconium. 
     
     
         4 . The silicon alloy of  claim 1 , wherein the total amount of unavoidable elements from the group consisting of iron, nickel, chromium, molybdenum, manganese, titanium, yttrium, magnesium, calcium, zirconium, vanadium, boron, tungsten and cobalt in the alloy is less than 0.3% by weight. 
     
     
         5 . A silicon alloy powder, the grains of which are composed of the silicon alloy of  claim 4  and have diameters less than or equal to 1 micron. 
     
     
         6 . A silicon alloy powder according to  claim 5 , including a sintering additive comprising 0.1-10% by weight of an oxide of at least one element from the group consisting of yttrium, ytterbium, aluminum and zirconium. 
     
     
         7 . The silicon alloy of  claim 1 , wherein 0.3-10% by weight of the alloy is composed of at least one subsidiary alloy element from the group consisting of iron, nickel, chromium, molybdenum, manganese, titanium, yttrium, magnesium, calcium, zirconium, vanadium, boron, tungsten and cobalt. 
     
     
         8 . A silicon alloy powder, the grains of which are composed of the silicon alloy of  claim 7  and have diameters less than or equal to 1 micron. 
     
     
         9 . A silicon alloy powder according to  claim 8 , including a sintering additive comprising 0.1-10% by weight of an oxide of at least one element from the group consisting of yttrium, ytterbium, aluminum and zirconium. 
     
     
         10 . A controlled combustion synthesis apparatus comprising:
 a reaction container;   at least one ignition system;   a pressure sensor for detecting the internal pressure of the reaction container;   a nitrogen feed system for supplying nitrogen from the exterior to the reaction container;   a pressure control system including a gas pressure control valve for feeding nitrogen to, and exhausting reactant gas from, the reaction container;   means for detecting the internal temperature of a reaction container,   a first cooling system comprising a water-cooled jacket covering substantially the entire reaction container; and   a second cooling system comprising a cooling plate installed in the reaction container;   wherein the apparatus further comprises a temperature control system which controls the inner temperature of the reaction container by controlling the flow of cooling water supplied to said first and second cooling systems in response to the temperature detected by said temperature detecting means;   whereby combustion synthesis can be carried out while maintaining the internal pressure and temperature of said reaction container at specified values.   
     
     
         11 . A process for manufacturing a silicon sintered alloy comprising:
 a hydrous compounding step which uses, as a raw material, a silicon alloy powder the grains of which are composed of a silicon alloy including 30-70 weight % silicon, 10-45 weight % nitrogen, 1-40 weight % aluminum and 1-40 weight % oxygen, and have diameters less than or equal to 1 micron;   a forming step to form an intermediate product or a final product;   a drying step to reduce the amount of the included water to less than 1% by weight;   a sintering step in which green bodies formed in the forming and drying steps are heated, by millimeter waves at a frequency of at least 15 GHz, to a temperature within the range from 1300 to 1900 degrees Celsius for a time period in the range from 30 minutes to 3 hours, within a nitrogen atmosphere held to a pressure at least as high as atmospheric pressure.   
     
     
         12 . A process according to  claim 11 , wherein the silicon alloy powder includes a sintering additive comprising 0.1-10% by weight of an oxide of at least one element from the group consisting of yttrium, ytterbium, aluminum and zirconium. 
     
     
         13 . A process according to  claim 11 , wherein a kneading operation is carried out in at least one of said hydrous compounding and forming steps in a reduced pressure atmosphere less than or equal to the atmospheric pressure. 
     
     
         14 . A manufacturing process according to  claim 11 , wherein said green bodies are sintered by heating in the nitrogen atmosphere at atmospheric pressure, or by a HIP sintering process in a nitrogen atmosphere. 
     
     
         15 . A process according to  claim 14 , wherein a kneading operation is carried out in at least one of said hydrous compounding and forming steps in a reduced pressure atmosphere less than or equal to the atmospheric pressure. 
     
     
         16 . A process according to  claim 11 , in which an inorganic binder is added to said raw material before the forming step, the inorganic binder being present in an amount in the range from 0.1-10% of the weight of silicon and aluminum in the raw material. 
     
     
         17 . A process according to  claim 16 , wherein the silicon alloy powder includes a sintering additive comprising 0.1-10% by weight of an oxide of at least one element from the group consisting of yttrium, ytterbium, aluminum and zirconium. 
     
     
         18 . A process according to  claim 16 , wherein a kneading operation is carried out in at least one of said hydrous compounding and forming steps in a reduced pressure atmosphere less than or equal to atmospheric pressure. 
     
     
         19 . A manufacturing process according to  claim 16 , wherein said green bodies are sintered by heating in the nitrogen atmosphere at atmospheric pressure, or by a HIP sintering process in a nitrogen atmosphere. 
     
     
         20 . A process according to  claim 19 , wherein a kneading operation is carried out in at least one of said hydrous compounding and forming steps in a reduced pressure atmosphere less than or equal to the atmospheric pressure.