Plasma-assisted sintering

Abstract

Methods and systems for plasma-assisted sintering are provided. The method can include initiating a sintering plasma with a cavity ( 12 ) by subjecting a gas to radiation in the presence of a plasma catalyst and exposing at least a portion of an object which can be a powdered material component to the plasma for a period of time sufficient to sinter at least a portion of the object.

1 . A method of plasma-assisted sintering of an object including at least one powdered material component, the method comprising: 
 initiating a plasma in a first cavity by subjecting a gas in the first cavity to electromagnetic radiation having a frequency less than about 333 GHz in the presence of a plasma catalyst; and    exposing at least a portion of the object to the plasma for a period of time sufficient to sinter at least a portion of the at least one powdered material component.    
     
     
         2 . The method of  claim 1 , wherein the plasma catalyst includes at least one of a passive plasma catalyst and an active plasma catalyst.  
     
     
         3 . The method of  claim 1 , wherein the plasma catalyst includes at least one of powdered carbon, carbon nanotubes, carbon nanoparticles, carbon fibers, graphite, solid carbon, and any combination thereof.  
     
     
         4 . The method of  claim 1 , wherein the plasma catalyst includes at least one of x-rays, gamma radiation, alpha particles, beta particles, neutrons, protons, and any combination thereof.  
     
     
         5 . The method of  claim 1 , wherein the plasma catalyst includes at least one of electrons and ions.  
     
     
         6 . The method of  claim 1 , wherein the plasma catalyst includes at least one of a metal, carbon, a carbon-based alloy, a carbon-based composite, an electrically conductive polymer, a conductive silicone elastomer, a polymer nanocomposite, an organic-inorganic composite, and any combination thereof.  
     
     
         7 . The method of  claim 1 , further comprising placing the portion of the object in a location selected from within the first cavity and adjacent an aperture in the first cavity.  
     
     
         8 . The method of  claim 7 , wherein the initiating occurs in the first cavity in a gaseous environment having an initial pressure level of at least about 760 Torr.  
     
     
         9 . The method of  claim 1 , wherein the exposing causes heating of the at least a portion of the object that proceeds at a rate of at least 400 degrees Celsius per minute until the portion of the object reaches a temperature no greater than about a melting temperature of the at least one powdered material component.  
     
     
         10 . The method of  claim 1 , wherein the object includes multiple powder material components, and wherein the exposing causes heating of the at least a portion of the object that proceeds at a rate of at least 400° C. per minute until the portion of the object reaches a temperature up to a melting temperature for any one of the multiple powder material components.  
     
     
         11 . The method of  claim 1 , further comprising flowing gas through the first cavity.  
     
     
         12 . The method of  claim 1 , further comprising sustaining the plasma by directing additional radiation into the first cavity.  
     
     
         13 . The method of  claim 12 , further comprising mode-mixing the additional radiation.  
     
     
         14 . The method of  claim 1 , further comprising moving the object with respect to the plasma during the exposing.  
     
     
         15 . The method of  claim 1 , wherein the powdered material component comprises a material selected from a group consisting of a metal, a ceramic, an ore, a salt, an alloy, silicon, aluminum, tungsten, carbon, iron, an oxygen-containing compound, a nitrogen containing compound, and any combination thereof.  
     
     
         16 . The method of  claim 1 , wherein the first cavity has an interior surface with at least one surface feature, wherein the exposing comprises forming a sintering pattern on the object based on the at least one surface feature.  
     
     
         17 . The method of  claim 1 , wherein the first cavity is connected to a second cavity through a conduit, the method further comprising: 
 placing the object in the second cavity;    sustaining the plasma in the first cavity during the exposing; and    forming a plasma jet in the second cavity at the conduit, thereby permitting the exposing to occur in the second cavity.    
     
     
         18 . The method of  claim 1 , wherein the first cavity is formed in a vessel that has an aperture, the method further comprising: 
 placing the object outside the first cavity near the aperture;    sustaining the plasma in the first cavity during the exposing; and    forming a plasma jet at the aperture, thereby permitting the exposing to occur outside the first cavity.    
     
     
         19 . The method of  claim 1 , further comprising: 
 supplying a source of a processing material to the plasma, and    subjecting the object to a treatment using the processing material.    
     
     
         20 . The method of  claim 19 , wherein the processing material includes carbon and the treatment comprises carbunizing.  
     
     
         21 . The method of  claim 19 , wherein the processing material includes nitrogen and the treatment comprises nitriding.  
     
     
         22 . The method of  claim 19 , further comprising: 
 supplying a coating material to the plasma, and    depositing a coating on the object.    
     
     
         23 . The method of  claim 22 , wherein the coating includes at least one of tungsten carbide, tungsten nitride, tungsten oxide, tantalum nitride, tantalum oxide, titanium oxide, titanium nitride, silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, aluminum carbide, boron nitride, boron carbide, boron oxide, gallium phosphide, aluminum phosphide, chromium oxide, tin oxide, yttria, zirconia, silicon-germanium, indium tin oxide, indium gallium arsenide, aluminum gallium arsenide, boron, chromium, gallium, germanium, indium, phosphorus, magnesium, silicon, tantalum, tin, titanium, tungsten, yttrium, and zirconium.  
     
     
         24 . The method of  claim 22 , wherein at least one of the steps of subjecting the object to a treatment and depositing a coating on the object is performed in a location where the exposing at least a portion of the object to the plasma occurs.  
     
     
         25 . A system for plasma-assisted sintering of an object including at least one powdered material component, the system comprising: 
 a plasma catalyst;    a vessel in which a first cavity is formed and in which a plasma can be initiated by subjecting a gas to an amount of electromagnetic radiation having a frequency less than about 333 GHz in the presence of the plasma catalyst, wherein the vessel has a shape that permits at least a portion of the object to be exposed to the plasma;    a radiation source coupled to the cavity such that the radiation source can direct radiation into the cavity; and    a gas source coupled to the cavity such that a gas can flow into the cavity during sintering.    
     
     
         26 . The system of  claim 25 , wherein the cavity has an aperture at which a plasma jet can form.  
     
     
         27 . The system of  claim 25 , further comprising: 
 a temperature sensor for monitoring a temperature of the object; and    a controller that adjusts a power level of the radiation source in response to the temperature of the object.    
     
     
         28 . The system of  claim 27 , wherein the controller is programmed to control the power level of the radiation source such that the temperature of the object substantially conforms to a predetermined temperature profile.  
     
     
         29 . The system of  claim 27 , further comprising an applicator that contains the vessel, where the applicator is a multi-mode applicator.  
     
     
         30 . The system of  claim 29 , further comprising a mode mixer that can move relative to the applicator to make a time-averaged radiation density in a treatment zone of the applicator substantially uniform.  
     
     
         31 . The system of  claim 27 , further comprising an electrical bias source configured to be connected to the object during sintering.  
     
     
         32 . The system of  claim 31 , wherein the electrical bias-source generates an AC bias.  
     
     
         33 . The system of  claim 31 , wherein the electrical bias source generates a DC bias.  
     
     
         34 . The system of  claim 31 , wherein the electrical bias source generates a pulsed DC bias.  
     
     
         35 . The system of  claim 27 , further comprising a magnetic field source positioned to apply a magnetic field to the portion of the object during sintering.  
     
     
         36 . The system of  claim 29 , wherein the applicator includes an outer housing comprising a material that is substantially opaque to the radiation.  
     
     
         37 . The system of  claim 36 , wherein the applicator includes the vessel, which comprises a material that is substantially transmissive to the radiation.  
     
     
         38 . The system of  claim 25 , wherein the plasma catalyst includes at least one of a passive plasma catalyst and an active plasma catalyst.  
     
     
         39 . The system of  claim 25 , wherein the plasma catalyst includes at least one of powdered carbon, carbon nanotubes, carbon nanoparticles, carbon fibers, graphite, solid carbon, and any combination thereof.  
     
     
         40 . The system of  claim 25 , wherein the plasma catalyst includes at least one of x-rays, gamma radiation, alpha particles, beta particles, neutrons, protons, and any combination thereof.  
     
     
         41 . The system of  claim 25 , wherein the plasma catalyst includes at least one of electrons and ions.  
     
     
         42 . The system of  claim 25 , wherein the plasma catalyst includes at least one of a metal, carbon, a carbon-based alloy, a carbon-based composite, an electrically conductive polymer, a conductive silicone elastomer, a polymer nanocomposite, an organic-inorganic composite, and any combination thereof.