Process for forming an improved metal alloy stent
First Claim
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1. A method for forming a medical device comprising the steps of:
- a) forming a rod or tube having a surface and an outer diameter, said rod or tube is a metal alloy that is formed of at least about 99.9 weight percent of a solid solution and includes carbon and oxygen, said metal alloy including a majority weight percent molybdenum plus rhenium;
b) drawing down said outer diameter of said rod or tube by a reducing mechanism that reduces said outer diameter by less than about 25% each time said rod or tube is processed by said reducing mechanism;
c) cleaning said surface of said rod or tube after each of said step of drawing;
d) annealing said rod or tube prior to said rod or tube having said outer diameter draw down by more than about 50%; and
,e) controlling an atmosphere about said rod or tube during said steps of drawing and annealing so that said metal alloy of said rod or tube after final drawing and annealing steps includes less than about 20 ppm nitrogen, less than about 150 ppm carbon, and less than about 50 ppm oxygen and a carbon to oxygen atomic ratio of at least about 2;
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Abstract
A method and process for at least partially forming a medical device that is at least partially formed of a novel metal alloy which improves the physical properties of the medical device.
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Citations
56 Claims
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1. A method for forming a medical device comprising the steps of:
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a) forming a rod or tube having a surface and an outer diameter, said rod or tube is a metal alloy that is formed of at least about 99.9 weight percent of a solid solution and includes carbon and oxygen, said metal alloy including a majority weight percent molybdenum plus rhenium; b) drawing down said outer diameter of said rod or tube by a reducing mechanism that reduces said outer diameter by less than about 25% each time said rod or tube is processed by said reducing mechanism; c) cleaning said surface of said rod or tube after each of said step of drawing; d) annealing said rod or tube prior to said rod or tube having said outer diameter draw down by more than about 50%; and
,e) controlling an atmosphere about said rod or tube during said steps of drawing and annealing so that said metal alloy of said rod or tube after final drawing and annealing steps includes less than about 20 ppm nitrogen, less than about 150 ppm carbon, and less than about 50 ppm oxygen and a carbon to oxygen atomic ratio of at least about 2;
1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for forming a medical device comprising the steps of:
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a) selecting at least two different metal powders, said metal powders having an average particle size of less than about 200 mesh; b) substantially homogeneously mixing together said metal powders; c) forming a tube from said metal powders by pressing said metal powders together and sintering said metal powders, said tube having a surface and an outer diameter, said tube is a metal alloy that is formed of at least about 99.9 weight percent of a solid solution and includes carbon and oxygen, said metal alloy including a majority weight percent molybdenum plus rhenium; d) drawing down said outer diameter of said formed tube by a plug drawing process to reduce said outer diameter of said tube by less than about 15% each time said tube is processed by said plug drawing process; e) cleaning said surface of said tube after each of said plug drawing process; f) annealing said tube prior to said tube having said outer diameter draw down by more than about 45% since said tube had been last sintered or annealed; g) controlling an atmosphere about said rod or tube during said steps of drawing and annealing so that said metal alloy of said rod or tube after final drawing and annealing steps includes less than about 20 ppm nitrogen, less than about 150 ppm carbon, and less than about 50 ppm oxygen and a carbon to oxygen atomic ratio of at least about 2;
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,h) laser cutting said annealed tube to at least partially form said medical device, said tube at least partially stabilized during said laser cutter such than an average amplitude of vibration of said tube during said laser cutter is no more than about 50% of a wall thickness of said tube. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A method for forming a medical device comprising the steps of:
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a) forming a tube having a surface and an outer diameter, said tube is a metal alloy that is formed of at least about 99 weight percent of a solid solution, said metal alloy including at least about 40 weight percent rhenium, at least about 45 weight percent molybdenum, a total weight percent of said rhenium and said molybdenum in said metal alloy is at least about 95 weight percent; b) drawing down said outer diameter of said tube by a reducing mechanism that reduces said outer diameter by less than about 25% each time said tube is processed by said reducing mechanism, said step of drawing down said outer diameter of said tube at least partially occurs in an inert atmosphere, an oxygen reducing atmosphere, or a vacuum; c) cleaning said surface of said tube each time after said tube is drawn down; d) annealing said tube prior to said tube having said outer diameter draw down by more than about 50%, said step of annealing said tube occurs at a temperature of at least about 1300°
C. for at least about 2 minutes, said step of annealing said tube occurs at least partially occurs in an inert atmosphere, an oxygen reducing atmosphere, or a vacuum, said tube having a final wall thickness of less than about 0.095 inch after said steps of drawing and annealing are complete; and
,e) controlling an atmosphere about said tube during said steps of drawing and annealing so that said metal alloy of said tube after final drawing and annealing steps includes less than about 20 ppm nitrogen, less than about 150 ppm carbon, and less than about 50 ppm oxygen and a carbon to oxygen atomic ratio of at least about 2;
1. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
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Specification