Method of producing a tubular target

Abstract

A method for producing a tubular target formed of molybdenum or a molybdenum alloy which has an oxygen content of less than 50 μg/g, a density of greater than 99% of the theoretical density and an average grain size of less than 100 μm and which is connected to a supporting tube. The molybdenum or molybdenum alloy tube is produced by extrusion.

1 . A method of producing a tubular target, the method which comprises the following steps: 
 providing a metal powder of Mo or an Mo alloy with an average particle size according to Fisher of from 0.5 to 10 μm;    cold-isostatic pressing the metal powder in a flexible mold using a core at a pressure p, where 100 MPa<p<500 MPa, for producing a green compact in the form of a tube blank;    producing a tube blank by sintering the green compact at a temperature T, where 1600° C.<T<2500° C., in a reducing atmosphere or a vacuum;    producing a tube by heating the tube blank to a forming temperature T, where DBTT<T<(T S  minus 800° C.) and extruding over a mandrel;    joining the tube to a supporting tube of non-magnetic material and mechanically processing, to form a tubular target of a tube of molybdenum or a molybdenum alloy with an oxygen content of less than 50 μg/g, a density of greater than 99% of the theoretical density and an average grain size transversely to the axial direction of less than 100 μm, and the supporting tube.    
   
   
       2 . The method according to  claim 1 , which comprises machining the sintered tube blank.  
   
   
       3 . The method according to  claim 1 , which comprises fastening a steel tube end piece with an outer diameter and an inner diameter approximately equal to an outer diameter and and inner diameter, respectively, of the tube blank to at least one end of the tube blank.  
   
   
       4 . The method according to  claim 1 , which comprises annealing the extruded tube in the reducing atmosphere or a vacuum at an annealing temperature T of 800° C.<T<1600° C.  
   
   
       5 . The method according to  claim 1 , wherein the supporting tube consists of a copper alloy, austenitic steel, titanium, or a titanium alloy.  
   
   
       6 . The method according to  claim 1 , wherein the supporting tube consists of Cu—Cr—Zr.  
   
   
       7 . The method according to  claim 1 , which comprises connecting the supporting tube by a joining process to the tube of molybdenum or molybdenum alloy, to thereby cause a plastic deformation of the supporting tube.  
   
   
       8 . The method according to  claim 7 , which comprises connecting the supporting tube to the tube of molybdenum or a molybdenum alloy by a forming process.  
   
   
       9 . The method according to  claim 1 , which comprises using glass powder for lubrication during the extrusion.  
   
   
       10 . The method according to  claim 1 , which comprises extruding with a degree of forming of 40 to 80%.  
   
   
       11 . The method according to  claim 1 , which comprises straightening the extruded tube on a mandrel by a forging process.  
   
   
       12 . The method according to  claim 1 , which comprises deforming the extruded tube on a mandrel by a forging process in such a way that a wall thickness differs over a length of the tube.  
   
   
       13 . The method according to  claim 12 , which comprises deforming the extruded tube in such a way that a wall thickness of the tube increases towards the ends of the tube.  
   
   
       14 . The method according to  claim 1 , wherein the molybdenum tube consists of pure molybdenum with an metallic purity, exclusive of tungsten, of greater than 99.99% by weight.  
   
   
       15 . The method according to  claim 1 , wherein the molybdenum tube consists of a molybdenum alloy containing 0.5 to 30% by weight of at least one of V, Nb, Ta, Cr, and W.  
   
   
       16 . A deposition process, which comprises forming a tubular target according to the method of  claim 1  and utilizing the tubular target in the production of LCD-TFT flat screens.  
   
   
       17 . A deposition process, which comprises forming a tubular target according to the method of  claim 1  and utilizing the tubular target for glass coating.  
   
   
       18 . A method of producing a tubular target, which comprises the following method steps: 
 providing a metal powder of Mo or an Mo alloy with an average particle size according to Fisher of from 0.5 to 10 μm;    cold-isostatic pressing the metal powder in a flexible mold using a core at a pressure p, where 100 MPa<p<500 MPa, for producing a green compact in the form of a tube blank;    sintering the green compact at a temperature T, where 1600° C.<T<2500° C., in a reducing atmosphere or a vacuum for producing a tube blank;    working the tube blank and joining at least one steel tube end piece for fixing a supporting tube of austenitic steel blank inside the tube blank;    producing a composite tube by heating to a forming temperature T, where 900<T<1350° C. and co-extruding over a mandrel; and    machining the composite tube for forming a tubular target with a tube of molybdenum or a molybdenum alloy with an oxygen content of less than 50 μg/g, a density of greater than 99% of theoretical density, and an average grain size transversely to an axial direction of less than 100 μm, and the supporting tube.    
   
   
       19 . The method according to  claim 18 , which comprises annealing the composite tube in a reducing atmosphere or a vacuum at an annealing temperature T of 800° C.<T<1300° C.  
   
   
       20 . The method according to  claim 18 , which comprises forming the assembly with a gap of 0.2 to 1 mm between the tube blank and the supporting tube blank.  
   
   
       21 . The method according to  claim 18 , which comprises forming the assembly with gap of from 3 mm to 20 mm between the tube blank and the supporting tube blank and filling the gap with steel powder.  
   
   
       22 . The method according to  claim 18 , which comprises using glass powder for lubrication during the extrusion.  
   
   
       23 . The method according to  claim 18 , which comprises extruding with a degree of forming of 40 to 80%.  
   
   
       24 . The method according to  claim 18 , which comprises straightening the composite tube on a mandrel by a forging process.  
   
   
       25 . The method according to  claim 18 , which comprises deforming the composite tube on a mandrel by a forging process in such a way that a wall thickness differs over a length of the tube.  
   
   
       26 . The method according to  claim 25 , which comprises deforming the composite tube in such a way that the a wall thickness of the tube increases towards the ends of the tube.  
   
   
       27 . The method according to  claim 18 , wherein the molybdenum tube consists of pure molybdenum with an metallic purity, exclusive of tungsten, of greater than 99.99% by weight.  
   
   
       28 . The method according to  claim 18 , wherein the molybdenum tube consists of a molybdenum alloy containing 0.5 to 30% by weight of at least one of V, Nb, Ta, Cr, and W.  
   
   
       29 . A deposition process, which comprises forming a tubular target according to the method of  claim 18  and utilizing the tubular target in the production of LCD-TFT flat screens.  
   
   
       30 . A deposition process, which comprises forming a tubular target according to the method of  claim 18  and utilizing the tubular target for glass coating.