Plasma spray apparatus

Abstract

A microplasma spray coating apparatus includes a microplasma apparatus with an anode, cathode, and an arc generator for generating an electric arc between the anode and cathode. An arc gas emitter injects inert gas through the electric arc. The electric arc is operable for ionizing the gas to create a plasma gas stream. A powder injector nozzle extends through the anode and injects powdered material into the plasma stream for transfer to the workpiece.

1 . A microplasma spray apparatus for coating a workpiece, comprising: 
 an anode, a cathode, and an arc generator generating an electric arc between the anode and cathode;    a nozzle to emit arc gas into the electric arc, the electric arc operable for ionizing the gas to create a plasma gas stream; and    a feeder extending through the anode to provide powdered material into the plasma gas stream.    
   
   
       2 . (canceled)  
   
   
       3 . The microplasma spray apparatus of  claim 1 , wherein the feeder uses a carrier gas to entrain the powdered material through a powder injector nozzle.  
   
   
       4 . The microplasma spray apparatus of  claim 1 , further including a powder hopper for holding the powdered material prior to the powdered material being injected into the plasma gas stream.  
   
   
       5 . The microplasma spray apparatus of  claim 4 , wherein the powder hopper and feeder are combined in one apparatus.  
   
   
       6 . The microplasma spray apparatus of  claim 1 , wherein the cathode includes an electrode having a first end extending from a cathode housing and a second end terminating at a tip, the electrode operable for conducting electric current.  
   
   
       7 . The microplasma spray apparatus of  claim 6 , wherein the electrode includes a substantially circular cross section along at least a portion of a lengthwise axis.  
   
   
       8 . The microplasma spray apparatus of  claim 6 , wherein the electrode is formed with a desired surface angle extending from the tip toward the cathode housing.  
   
   
       9 . The microplasma spray apparatus of  claim 8 , wherein the angle is approximately 10 degrees.  
   
   
       10 . The microplasma spray apparatus of  claim 6 , wherein the tip includes a substantially flat forward edge.  
   
   
       11 . The microplasma spray apparatus of  claim 10 , wherein the flat forward edge of the tip is formed at a desired height.  
   
   
       12 . The microplasma spray apparatus of  claim 11 , wherein the height of the edge is approximately between 10% and 20% of a width of the electrode.  
   
   
       13 . The microplasma spray apparatus of  claim 1 , wherein a maximum surface temperature of the workpiece caused by the coating process is approximately 200° F.  
   
   
       14 . The microplasma spray apparatus of  claim 1 , wherein the plasma apparatus applies the coating material in widths of approximately 2 mm to the workpiece.  
   
   
       15 . The microplasma spray apparatus of  claim 1 , wherein the anode is formed from sintered tungsten material.  
   
   
       16 . The microplasma spray apparatus of  claim 1 , further including a shield gas cap having shielding gas injected therethrough.  
   
   
       17 . The microplasma spray apparatus of  claim 1 , wherein the powdered material is a metal alloy.  
   
   
       18 . The microplasma spray apparatus of  claim 1 , wherein the powdered material is a ceramic based coating.  
   
   
       19 . The microplasma spray apparatus of  claim 1 , further including a cooling system for cooling the plasma apparatus.  
   
   
       20 . The microplasma spray apparatus of  claim 1 , wherein the plasma apparatus is operable for spray coating a workpiece at any angle of orientation.  
   
   
       21 . The microplasma spray apparatus of  claim 1 , wherein the plasma apparatus generates a noise level of between approximately 40 and 70 decibels.  
   
   
       22 . The microplasma spray apparatus of  claim 1 , further including a cathode shroud surrounding a portion of the cathode.  
   
   
       23 . The microplasma spray apparatus of  claim 22 , wherein the arc gas nozzle is positioned in a receiving aperture formed in the cathode shroud.  
   
   
       24 . The microplasma spray apparatus of  claim 22 , further including a shield gas cap substantially encompassing the cathode shroud, the shield gas cap operable for providing shielding gas as a barrier between the arc gas and an ambient atmosphere.  
   
   
       25 . The microplasma spray apparatus of  claim 24 , further including a shield cap insulator positioned between the shield gas cap and the cathode shroud.  
   
   
       26 . A microplasma spray apparatus for coating a workpiece, comprising: 
 an anode, a cathode, and an arc generator to generate an electric arc between the anode and cathode,    a nozzle to emit arc gas into the electric arc, the electric arc ionizing the gas to create a plasma gas stream; and    a feeder providing powdered material to the plasma gas stream;    wherein the cathode includes an electrode having a taper terminating at a tip, the taper including a substantially flat edge having a predetermined height at the tip.    
   
   
       27 . (canceled)  
   
   
       28 . The microplasma spray apparatus of  claim 26 , wherein the feeder uses a carrier gas to entrain the powdered material through the anode.  
   
   
       29 . The microplasma spray apparatus of  claim 26 , further including a powder hopper for holding the powdered material prior to the powdered material being injected into the plasma gas stream.  
   
   
       30 . The microplasma spray apparatus of  claim 29 , wherein the powder hopper and feeder are combined in one apparatus.  
   
   
       31 . The microplasma spray apparatus of  claim 26 , wherein the surface angle of the taper is approximately between 8 and 10 degrees.  
   
   
       32 . The microplasma spray apparatus of  claim 26 , wherein the height of the edge is approximately between 10% and 20% of a width of the electrode.  
   
   
       33 . The microplasma spray apparatus of  claim 26 , further including a powder injector nozzle connected to the feeder, the powder injector nozzle extending through the anode and injecting powdered material into the plasma gas stream.  
   
   
       34 . The microplasma spray apparatus of  claim 26 , wherein the plasma apparatus operates at a power range of between approximately 0.5 Kilowatts and 2.5 Kilowatts.  
   
   
       35 . The microplasma spray apparatus of  claim 26 , wherein a maximum surface temperature of the workpiece caused by the coating process is approximately 200° F.  
   
   
       36 . The microplasma spray apparatus of  claim 26 , wherein the plasma apparatus applies the coating material in widths of approximately 2 mm to the workpiece.  
   
   
       37 . The microplasma spray apparatus of  claim 26 , further including a shield gas cap having shielding gas injected therethrough.  
   
   
       38 . The microplasma spray apparatus of  claim 26 , wherein the coating material is a metal alloy.  
   
   
       39 . The microplasma spray apparatus of  claim 26 , wherein the coating material is a ceramic based coating.  
   
   
       40 . The microplasma spray apparatus of  claim 26 , further including a cooling system for cooling the plasma apparatus.  
   
   
       41 . The microplasma spray apparatus of  claim 26 , wherein the plasma apparatus is operable for spray coating a workpiece at any angle of orientation.  
   
   
       42 . The microplasma spray apparatus of  claim 26 , wherein the plasma apparatus generates a noise level of between approximately 40 and 70 decibels.  
   
   
       43 . The microplasma spray apparatus of  claim 26 , further including a cathode shroud surrounding a portion of the cathode.  
   
   
       44 . The microplasma spray apparatus of  claim 43 , wherein the nozzle is positioned in a receiving aperture formed in the cathode shroud.  
   
   
       45 . The microplasma spray apparatus of  claim 43 , further including a shield gas cap substantially encompassing the cathode shroud, the shield gas cap operable for providing shielding gas as a barrier between the arc gas and an ambient atmosphere.  
   
   
       46 . The microplasma spray apparatus of  claim 45 , further including a shield cap insulator positioned between the shield gas cap and the cathode shroud.  
   
   
       47 . The microplasma spray apparatus of  claim 26 , wherein the anode is formed from a commercially pure tungsten material.  
   
   
       48 . A method for injecting powdered material into a plasma gas stream, comprising: 
 positioning a powder injector nozzle through an anode of a microplasma spray apparatus;    transporting powdered material from a powder hopper to the powder injector nozzle; and    injecting the powdered material into the plasma gas stream.    
   
   
       49 . (canceled)  
   
   
       50 . The method of  claim 48 , further comprising: entraining powdered material with carrier gas flowing from a powder feeder through the injector nozzle.  
   
   
       51 . The method of  claim 48 , further comprising: preheating the powdered material in the powder injector nozzle with electric current running through the anode.  
   
   
       52 . A microplasma spray apparatus, comprising: 
 an anode, cathode and an arc generator for generating an electric arc between the anode and the cathode;    a nozzle for emitting arc gas into the electric arc, the electric arc ionizing the gas to create a plasma gas stream; and    a feeder for providing powdered material to the plasma gas stream;    wherein the feeder provides the powdered material to the plasma gas stream from a direction other than above the plasma gas stream.    
   
   
       53 . (canceled)  
   
   
       54 . The microplasma spray apparatus of  claim 52 , wherein the direction is from beneath the plasma gas stream.  
   
   
       55 . A microplasma spray apparatus, comprising: 
 an anode formed from a commercially pure tungsten material;    a cathode operationally coupled to the anode;    an arc generator for generating an electric arc between the anode and cathode;    a nozzle for emitting arc gas into the electric arc, the electric arc ionizing the gas to create a plasma gas stream; and    a feeder for providing powdered material to the plasma gas stream.    
   
   
       56 . (canceled)