Method for preparing shape memory alloy intravascular stent based on automatic powder laying laser combination machining technology

A vascular stent and combined processing technology, which is applied in the field of medical device manufacturing, can solve problems such as size deformation, difficulty in realizing complex shapes, warping deformation, etc., and achieve the effect of reducing size error and trauma area

Active Publication Date: 2015-11-11

NANJING UNIV OF AERONAUTICS & ASTRONAUTICS +2

6 Cites 17 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0004] Although the above-mentioned nickel-titanium alloy has many excellent characteristics, it has the following disadvantages: 1. The cost and difficulty of the processing and post-treatment process of the nickel-titanium alloy stent are higher than those of stainless steel 316L. The commonly used nickel-titanium alloy vascular stent is usually It is braided by shape memory alloy wire or shaped by laser engraving of shape memory alloy. It can be seen that such vascular stents have high production costs, limited stent structure design, and it is difficult to realize complex shapes of vascular stents. 2. The temperature sensitivity of Nitinol stent is very high, and obvious temperature changes will cause changes in the performance of the stent. Therefore, it has a certain impact on storage and transportation. condition requirements; at present, the commonly used nickel-titanium alloy stent is a self-expanding stent, which needs to cooperate with the delivery sheath to be transported t...

Abstract

The invention discloses a method for preparing a shape memory alloy intravascular stent based on the automatic powder laying laser combination machining technology. The method comprises the steps that according to a three-dimensional data model of a part to be machined, a high-energy laser beam melting and mixing powder system is utilized, the manner of laying powder layer by layer and carrying out fusing overlaying accumulation layer by layer is carried out until a intravascular stent blank of a mesh structure is formed finally, and then electrochemical polishing is carried out to reach the specific surface roughness requirement. The intravascular stent prepared through the method is based on the unique superelasticity function and the shape memory effect of shape memory alloy, and the occurrence rate of vascular restenosis of the intravascular stent in clinical application can be effectively reduced; by means of mechanical performance and living body environment simulation tests, the intravascular stent has the good biological tissue and blood compatibility and meets the medical application condition; furthermore, based on the advantage of superhigh manufacturing precision of the laser combination machining technology and protection of inert gas in the forming process, the problems of surface roughness, burr, oxidation and the like of a traditional intravascular stent in the preparing process are effectively solved.

Application Domain

Additive manufacturing apparatusIncreasing energy efficiency

Technology Topic

Biological tissuePercent Diameter Stenosis +16

Image

Examples

Experimental program(4)

Example Embodiment

[0050] Example 1

[0051] Step (1): Build a model

[0052] Establish the three-dimensional geometric model of the blood vessel stent in the computer, import the three-dimensional geometric model into the layered slice software for layered discretization, with a layer thickness of 30μm, obtain the cross-sectional profile data and form the scanning path;

[0053] Step (2): Preparation of the original powder material

[0054] A mixed powder material with an average particle size of 20μm is made from Ni-Ti metal powder and added Co metal powder at a mass ratio of 50:49:1.0 at a temperature of 120°C;

[0055] In this step, the Ni-Ti metal powder and the added Co metal powder can also be prepared according to other mass ratios, as long as the mass ratio of nickel, titanium, and Co meets 40-60:40-60:0.5-1.0 At the same time, the temperature during preparation is not limited to 120 degrees, as long as it is between 100-150 degrees Celsius; the average particle size of the mixed powder material can also vary, as long as it is controlled between 5 and 25 μm.

[0056] Step (3): Laser laminated manufacturing

[0057] Load the vascular stent digital file obtained in step (1) to the corresponding interface of the laser processing equipment, and set the processing parameters on the equipment operation interface. The laser beam focus spot diameter is 35μm, the laser power is 100W, and the laser scanning rate is 300mm/s. , The scanning distance is 20μm, the original powder prepared in step (2) is sent to the molding cavity by the powder feeding device, and the powder material is evenly pre-placed on the substrate by the powder spreading device. The preheating temperature of the substrate is 120 At the same time, inert gas is introduced into the molding cavity to reduce the oxygen content in the molding cavity. The oxygen content is controlled to 8ppm, and then the first layer of metal powder is melted by a high-energy laser beam, and the substrate is controlled by a computer to lower the height of 30μm for the next step. The processing of thin metal layers, layer by layer fusion and accumulation, until the final vascular stent blank is obtained;

[0058] Step (4): Post-processing

[0059] The vascular stent blank obtained in step (3) is electrochemically polished, methanol-perchloric acid is selected as the electrolyte solution, and 90 ml of polishing additives are added to the electrolyte solution. The temperature is set to 20°C, the anode and cathode spacing is 2.0 cm, and the current The density is 0.70A/cm 2 , The polishing time is 45s, and the Ni-Ti-Co shape memory alloy vascular stent with smooth surface is obtained after electrochemical polishing.

Example Embodiment

[0060] Example 2

[0061] Step (1): Build a model

[0062] Establish the three-dimensional geometric model of the blood vessel stent in the computer, import the three-dimensional geometric model into the layered slicing software for layered discretization, with the layered thickness of 35μm, obtain the cross-sectional profile data and form the scanning path;

[0063] Step (2): Preparation of the original powder material

[0064] A mixed powder material with an average particle size of 15μm is made from Ni-Ti metal powder and added Cr metal powder at a mass ratio of 50.2:50:0.8 at a temperature of 120°C;

[0065] In this step, the Ni-Ti metal powder and the added Cr metal powder can also be prepared according to other mass ratios, as long as the mass ratio of nickel, titanium, and Cr satisfies 40-60:40-60:0.5-1.0 At the same time, the temperature during preparation is not limited to 120 degrees, as long as it is between 100-150 degrees Celsius; the average particle size of the mixed powder material can also vary, as long as it is controlled between 5 and 25 μm.

[0066] Step (3): Laser laminated manufacturing

[0067] Load the vascular stent digital file obtained in step (1) to the corresponding interface of the laser processing equipment, and set the processing parameters on the equipment operation interface. The laser beam focus spot diameter is 25μm, the laser power is 100W, and the laser scanning rate is 250mm/s. , The scanning distance is 20μm, the original powder prepared in step (2) is sent to the molding cavity by the powder feeding device, and the powder material is evenly pre-placed on the substrate by the powder spreading device. The preheating temperature of the substrate is 120 At the same time, inert gas is introduced into the molding cavity to reduce the oxygen content in the molding cavity. The oxygen content is controlled to 9ppm, and then the first layer of metal powder is melted by a high-energy laser beam, and the substrate is controlled by a computer to lower the height of 35μm for the next step. The processing of thin metal layers, layer by layer fusion and accumulation, until the final vascular stent blank is obtained;

[0068] Step (4): Post-processing

[0069] The vascular stent blank obtained in step (3) is electrochemically polished, methanol-perchloric acid is selected as the electrolyte solution, and 85 ml of polishing additives are added to the electrolyte solution. The temperature is set to 25°C, the distance between cathode and anode is 2.0 cm, and the current Density is 0.75A/cm 2 , The polishing time is 50s, and the Ni-Ti-Cr shape memory alloy vascular stent with smooth surface is obtained after electrochemical polishing.

Example Embodiment

[0070] Example 3

[0071] Step (1): Build a model

[0072] Establish the three-dimensional geometric model of the blood vessel stent in the computer, import the three-dimensional geometric model into the layered slicing software for layered discretization, with a layer thickness of 40μm, obtain cross-sectional profile data and form a scanning path;

[0073] Step (2): Preparation of the original powder material

[0074] A mixed powder material with an average particle size of 10μm is made from Ni-Ti metal powder and added V metal powder at a mass ratio of 50:49.3:0.7 at a temperature of 130°C;

[0075] In this step, the Ni-Ti metal powder and the added V metal powder can also be prepared according to other mass ratios, as long as the mass ratio of nickel, titanium, and V satisfies 40-60:40-60:0.5-1.0 At the same time, the temperature during preparation is not limited to 130 degrees, as long as it is between 100-150 degrees Celsius; the average particle size of the mixed powder material can also be changed, as long as it is controlled between 5-25μm.

[0076] Step (3): Laser laminated manufacturing

[0077] Load the vascular stent digital file obtained in step (1) to the corresponding interface of the laser processing equipment, and set the processing parameters on the equipment operation interface. The laser beam focus spot diameter is 30μm, the laser power is 140W, and the laser scanning rate is 200mm/s. , The scanning distance is 20μm, the original powder prepared in step (2) is sent to the molding cavity by the powder feeding device, and the powder material is evenly pre-placed on the substrate by the powder spreading device. The preheating temperature of the substrate is 135 At the same time, inert gas is introduced into the molding cavity to reduce the oxygen content in the molding cavity. The oxygen content is controlled to 10ppm. Then, the first layer of metal powder is melted by a high-energy laser beam, and the substrate is lowered by a computer to control the height of 40μm. The processing of thin metal layers, layer by layer fusion and accumulation, until the final vascular stent blank is obtained;

[0078] Step (4): Post-processing

[0079] The vascular stent blank obtained in step (3) is electrochemically polished, methanol-perchloric acid is selected as the electrolyte solution, and 85 ml of polishing additives are added to the electrolyte solution. The temperature is set to 24°C, the distance between cathode and anode is 2.0 cm, and the current Density is 0.75A/cm 2 , The polishing time is 50s, and the Ni-Ti-V shape memory alloy vascular stent with smooth surface is obtained after electrochemical polishing.

PUM

Property	Measurement	Unit
Thickness	20.0 ~ 50.0	µm
Surface roughness	75.0 ~ 85.0	µm
The average particle size	5.0 ~ 25.0	µm

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Method for preparing shape memory alloy intravascular stent based on automatic powder laying laser combination machining technology

A vascular stent and combined processing technology, which is applied in the field of medical device manufacturing, can solve problems such as size deformation, difficulty in realizing complex shapes, warping deformation, etc., and achieve the effect of reducing size error and trauma area

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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