Nickel-titanium shape memory alloy for endoscopic calculus removing net basket and preparation method of nickel-titanium shape memory alloy

Abstract

The invention discloses a nickel-titanium shape memory alloy for an endoscope calculus removing net basket and a preparation method of the nickel-titanium shape memory alloy, and belongs to the technical field of alloy preparation. The preparation method of the nickel-titanium shape memory alloy for the endoscopic calculus removing mesh basket comprises the following steps that firstly, high-purity nickel and titanium are subjected to smelting, cooling, surface layer substance removal, homogenizing annealing, hot rolling and water quenching, and a nickel-titanium alloy matrix is obtained; 2, modified carbon nanotubes are added into absolute ethyl alcohol to obtain suspension liquid, a nickel-titanium alloy matrix is subjected to cold rolling treatment, before each time of cold rolling treatment, the suspension liquid is evenly sprayed, treatment, drawing, low-temperature annealing and cooling are repeated, and a composite nickel-titanium alloy matrix is obtained; and thirdly, the composite nickel-titanium alloy base body is subjected to sand blasting treatment and ultrasonic cleaning, then a modified polymer solution is sprayed, curing and polishing are conducted, and the nickel-titanium shape memory alloy for the endoscope calculus removing net basket is obtained. The alloy material prepared by the method has excellent mechanical properties, corrosion resistance and shock resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of nickel-titanium shape memory alloys, and particularly relates to a nickel-titanium shape memory alloy for an endoscopic lithotripsy basket and a preparation method thereof. Background Art

[0002] Nickel-titanium shape memory alloy, also known as NiTi alloy or Nitinol, is a binary alloy composed of nickel and titanium elements in nearly equal concentrations. The unique feature of this alloy lies in its shape memory effect and superelasticity, that is, it can automatically restore its original shape under specific conditions or return to its original state after unloading the external force. This characteristic stems from the complex phase transformation process inside the NiTi alloy, especially the transformation from the austenite phase to the martensite phase. When the alloy is cooled from the austenite phase to the martensite phase and undergoes plastic deformation, as long as it is reheated to the austenite phase temperature, the material will automatically return to its original shape. This unique property makes the NiTi alloy have broad application potential in many fields, especially in the medical device field.

[0003] Patent CN112981179A discloses a nickel-titanium shape memory alloy material, an alloy wire and a preparation method and application thereof. The preparation method includes: casting and cooling the nickel-titanium alloy melt obtained by melting under mechanical vibration to obtain an ingot, and the mechanical vibration frequency is 45 - 55 Hz, and the amplitude is 12 - 20 cm. The alloy material and alloy wire prepared by this method have good mechanical properties and can be widely used in the medical device field. However, the strength, corrosion resistance and anti-vibration performance of the nickel-titanium shape memory alloy prepared by this method still have room for improvement. Summary of the Invention

[0004] The purpose of the present invention is to provide a nickel-titanium shape memory alloy for an endoscopic lithotripsy basket and a preparation method thereof, which are used to solve the technical problems of poor strength, corrosion resistance and anti-vibration performance of the nickel-titanium shape memory alloy in the prior art.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a preparation method of a nickel-titanium shape memory alloy for an endoscopic lithotripsy basket, including the following steps:

[0007] Step 1: Add high-purity nickel and titanium into a melting furnace for melting. After melting, cool, remove the surface layer substance, perform homogenization annealing, hot rolling, and water quenching to obtain a nickel-titanium alloy matrix;

[0008] Step 2: Add modified carbon nanotubes into absolute ethanol, perform ultrasonic dispersion to obtain a suspension, perform cold rolling treatment on the nickel-titanium alloy matrix, and uniformly spray the suspension before each cold rolling treatment. Repeat the treatment, perform drawing, low-temperature annealing, and cooling to obtain a composite nickel-titanium alloy matrix;

[0009] Step 3: Sandblast the composite nickel-titanium alloy matrix, ultrasonically clean it, then spray a modified polymer solution, cure it, and polish it to obtain a nickel-titanium shape memory alloy for endoscopic lithotripsy baskets.

[0010] Preferably, in Step 1, during the melting process, evacuate to ≤10 -3 Pa, introduce argon, the temperature is 1500 - 1600 °C, repeat the melting operation 3 - 5 times, the homogenization annealing temperature is 1000 - 1100 °C, hold for 12 - 24 h, and the hot rolling temperature is 800 - 950 °C.

[0011] Preferably, in Step 2, the dosage ratio of the modified carbon nanotubes to anhydrous ethanol is (10 - 20) g : (45 - 55) mL, the ultrasonic dispersion temperature is 40 - 45 °C, the time is 30 - 45 min, the low-temperature annealing temperature is 200 - 300 °C, and the holding time is 30 - 60 min.

[0012] Preferably, in Step 3, during the sandblasting process, use alumina sand with 80 - 120 meshes, the spray gun pressure is 0.4 - 0.6 MPa, the spraying angle is 90°, the spraying distance is 90 - 100 mm, ultrasonically clean with acetone, ethanol, and deionized water in sequence for 15 min, spray the modified polymer solution by electrostatic spraying, the spray gun voltage is 60 - 80 kV, the spraying distance is 100 - 150 mm, the air pressure is 0.3 - 0.5 MPa, and the curing process is: preheat at 120 °C for 10 min, hold at 250 °C for 30 min, and hold at 380 °C for 60 min.

[0013] Preferably, the preparation method of the modified carbon nanotubes includes the following steps:

[0014] Q1: Add 4-bromo-2-nitrobenzyl alcohol to N,N-dimethylformamide, then add 3-methylphenylboronic acid, tetrakis(triphenylphosphine)palladium, and sodium carbonate, heat and stir the reaction under nitrogen protection, after the reaction is completed, concentrate under reduced pressure and purify to obtain Intermediate 1;

[0015] Q2: Under a CO2 atmosphere, add Intermediate 1, 4-(trifluoromethyl)benzylamine, and tetrahydrofuran to a transparent container, irradiate with an ultraviolet lamp, catalytically stir the reaction at room temperature, after the reaction is completed, transfer to a rotary evaporation flask, add silica gel powder, reduce the pressure, separate and purify, and wash to obtain Intermediate 2;

[0016] Q3: Add carboxyl carbon nanotubes into absolute ethanol, disperse them by ultrasonic treatment, adjust the pH, heat-treat them in a water bath, centrifuge and filter, wash, dry, and grind to obtain acid-activated carboxyl carbon nanotubes. Add intermediate 2 and silane coupling agent KH-560 into a container, reflux and stir in a water bath. After the stirring ends, cool, add absolute ethanol, perform ultrasonic treatment, then add the absolute ethanol solution containing acid-activated carboxyl carbon nanotubes, heat and stir for reflux reaction. After the reaction ends, cool, centrifuge, wash, dry, and grind to obtain modified carbon nanotubes.

[0017] In the above process, the synthesis reaction formula of the modified carbon nanotubes is as follows:

[0018]

[0019] The results of mass spectrometry analysis of intermediate 1 are: m / z: 243.09 (100.0%), 244.09 (15.6%), 245.10 (1.1%); the results of mass spectrometry analysis of intermediate 2 are: m / z: 382.13 (100.0%), 383.13 (24.6%), 384.14 (2.8%).

[0020] Preferably, in Q1, the dosage ratio of 4-bromo-2-nitrobenzyl alcohol, N,N-dimethylformamide, 3-methylphenylboronic acid, tetrakis(triphenylphosphine)palladium, and sodium carbonate is (1.08 - 1.24) g : (18 - 24) mL : (1.12 - 1.58) g : (0.52 - 0.63) g : (0.98 - 1.13) g, the heating and stirring reaction temperature is 130 - 150 °C, and the reaction time is 8 - 10 h; in Q2, the dosage ratio of intermediate 1, 4-(trifluoromethyl)benzylamine, and tetrahydrofuran is (0.42 - 0.54) g : (0.38 - 0.46) g : (35 - 45) mL, the power of the ultraviolet lamp is 24 - 28 W, the wavelength of the ultraviolet lamp is 350 - 380 nm, and the stirring reaction time is 20 - 28 h.

[0021] Preferably, in Q3, the dosage ratio of carboxyl carbon nanotubes and absolute ethanol is (1 - 1.5) g : (400 - 600) mL, the ultrasonic dispersion time is 120 - 150 min, adjust the pH = 3 - 4, the water bath heat-treatment temperature is 50 - 60 °C, the treatment time is 6 - 8 h, the dosage ratio of intermediate 2, silane coupling agent KH-560, and acid-activated carboxyl carbon nanotubes is (1.45 - 1.87) g : (0.8 - 1.2) g : (1.1 - 1.5) g, the water bath reflux stirring temperature is 130 - 150 °C, the stirring time is 3 - 5 h, the ultrasonic treatment time is 30 - 45 min, the heating and stirring reflux reaction temperature is 80 - 85 °C, and the reaction time is 6 - 8 h.

[0022] Preferably, the preparation method of the modified polymer solution comprises the following steps:

[0023] S1: Add magnesium chips and iodine grains into a reaction flask, perform a vacuum-nitrogen purging cycle operation to fill the reaction flask with nitrogen. Subsequently, suck dry tetrahydrofuran and bromobenzene into syringes respectively, insert them into the rubber stopper of the reaction flask after exhausting the air, inject dry tetrahydrofuran and bromobenzene during stirring, heat, then place the reaction flask in an ice bath environment, continue to slowly inject dry tetrahydrofuran and bromobenzene. After the injection is completed, perform an oil bath heating and stirring reaction to obtain solution A;

[0024] S2: Add anthraquinone into a reaction vessel, seal it and perform vacuum-nitrogen purging, then inject dry tetrahydrofuran, cool down for reaction, and then slowly inject solution A into the reaction vessel using a syringe, perform a low-temperature stirring reaction, and then slowly add a saturated ammonium chloride aqueous solution to quench the reaction, perform rotary evaporation, extraction, collect the organic phase, dry, perform rotary evaporation and concentration, purification, and recrystallization to obtain product B;

[0025] S3: Add product B, 4,4'-difluorobenzophenone, sulfolane, potassium carbonate, and toluene into a container, perform a heating reaction under nitrogen protection. After the reaction is completed, crush and boil-wash to obtain a polymer. Add the polymer to ethanol, stir and mix evenly, then add polyethylene glycol, and perform ball milling to obtain the modified polymer solution.

[0026] In the above process, the synthesis reaction formula of the modified polymer is as follows:

[0027]

[0028] The mass spectrometry analysis result of product B is: m / z: 364.15 (100.0%), 365.15 (28.4%), 366.15 (4.2%).

[0029] Preferably, in S1, the dosage ratio of magnesium chips, iodine grains, dry tetrahydrofuran, and bromobenzene is (1.54 - 1.92) g : (0.002 - 0.003) g : (70 - 75) mL : (5.5 - 9.5) mL, the oil bath heating and stirring reaction temperature is 55 - 65 °C, and the reaction time is 3 - 5 h; in S2, the dosage ratio of anthraquinone, dry tetrahydrofuran, and solution A is (3 - 5) g : (150 - 190) mL : (70 - 75) mL, the cooling reaction temperature is -8 to -10 °C, the reaction time is 20 - 30 min, the low-temperature stirring reaction temperature is -1 to 0 °C, and the reaction time is 4 - 6 h.

[0030] Preferably, in the step S3, the usage ratio of product B, 4,4'-difluorobenzophenone, sulfolane, potassium carbonate and toluene is (2.01-2.35) g: (0.92-1.21) g: (7.5-8.1) mL: (0.8-0.86) g: (10-12) mL. The heating reaction process is as follows: maintain at 140°C for 1 h, maintain at 160°C for 1 h, maintain at 180°C for 1 h, maintain at 190°C for 3 h. The usage ratio of the polymer, ethanol and polyethylene glycol is (8-13) g: (20-25) mL: (1-1.25) g.

[0031] The nitinol shape memory alloy for endoscopic lithotripsy basket prepared by the method according to any one of claims 1-10.

[0032] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0033] 1. The present invention first uses 4-bromo-2-nitrobenzyl alcohol, 3-methylphenylboronic acid, 4-(trifluoromethyl)benzylamine, carboxyl carbon nanotubes and silane coupling agent KH-560 as the main raw materials to prepare modified carbon nanotubes. Subsequently, using bromobenzene, anthraquinone, 4,4'-difluorobenzophenone and polyethylene glycol as the main raw materials, a modified polymer solution is prepared and applied to the nitinol shape memory alloy for endoscopic lithotripsy basket, which can effectively improve its mechanical properties, corrosion resistance and shock resistance.

[0034] 2. The present invention adds the prepared modified carbon nanotubes to the preparation process of the nitinol shape memory alloy for endoscopic lithotripsy basket, which can effectively improve the mechanical properties, corrosion resistance and inhibit the release of nickel ions of the alloy. The modified carbon nanotubes are evenly distributed in the nitinol alloy matrix to form a three-dimensional network structure, significantly improving the tensile strength and yield strength of the alloy. The functional groups on the surface of the modified carbon nanotubes can form chemical bonds with the atoms in the nitinol alloy, and the interface bonding points can effectively pin the dislocation movement and hinder the grain boundary slip, improving the plasticity and toughness of the alloy. At the same time, the modified carbon nanotubes can cover the surface of the alloy to block the penetration of corrosive ions, thereby improving its corrosion resistance, and the carboxyl groups contained can 2+ have electrostatic attraction with Ni

[0035] 3. The modified polymer solution prepared in the present invention is sprayed onto the surface of the NiTi shape memory alloy for endoscopic lithotripsy baskets, which can effectively improve the mechanical properties of the alloy. The ether bonds and carbonyl groups contained in the prepared polymer can form hydrogen bonds or coordination bonds with the surface of the NiTi alloy, thereby enhancing the coating-matrix interfacial bonding force and improving the mechanical properties of the material. Moreover, the rigid backbone of the polymer main chain and the flexible segment of polyethylene glycol form a "rigid-flexible" structure, which converts mechanical energy into heat energy through internal friction of the segments during vibration, thereby reducing the vibration transmission rate and being more suitable for application in endoscopic lithotripsy baskets. Detailed implementation manners

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] Example 1: This example discloses a preparation method of modified carbon nanotubes, including the following steps:

[0038] Q1: Add 1.16 g of 4-bromo-2-nitrobenzyl alcohol to 21 mL of N,N-dimethylformamide, then add 1.35 g of 3-methylphenylboronic acid, 0.57 g of tetrakis(triphenylphosphine)palladium, and 1.05 g of sodium carbonate. Under nitrogen protection, heat and stir the reaction at 140 °C for 8 h. After the reaction is completed, concentrate under reduced pressure and purify to obtain intermediate 1;

[0039] Q2: Under a CO2 atmosphere, add 0.48 g of intermediate 1, 0.42 g of 4-(trifluoromethyl)benzylamine, and 40 mL of tetrahydrofuran to a transparent container, irradiate with a 28 W ultraviolet lamp (wavelength 360 nm), and catalytically stir the reaction at room temperature for 24 h. After the reaction is completed, transfer it to a rotary evaporation flask, add silica gel powder, reduce the pressure, separate and purify, and wash to obtain intermediate 2;

[0040] Q3: Add 1.25 g of carboxyl carbon nanotubes to 500 mL of absolute ethanol, ultrasonically disperse for 120 min, adjust the pH = 3, heat and treat in a water bath at 60 °C for 6 h, centrifuge, filter, wash, dry, and grind to obtain acid-activated carboxyl carbon nanotubes. Add 1.66 g of intermediate 2 and 1 g of silane coupling agent KH-560 to a container, reflux and stir in a water bath at 130 °C for 5 h. After the stirring is completed, cool, add 15 mL of absolute ethanol, ultrasonically treat for 45 min, then add 10 mL of an absolute ethanol solution containing 1.3 g of acid-activated carboxyl carbon nanotubes, heat and stir and reflux the reaction at 85 °C for 6 h. After the reaction is completed, cool, centrifuge, wash, dry, and grind to obtain modified carbon nanotubes.

[0041] This embodiment discloses a method for preparing a modified polymer solution, which includes the following steps:

[0042] S1: Add 1.73 g of magnesium chips and 0.0025 g of iodine grains into a reaction flask, perform the vacuum-purging nitrogen cycling operation to fill the reaction flask with nitrogen. Subsequently, suck 72.5 mL of dry tetrahydrofuran and 7.5 mL of bromobenzene into syringes respectively. After exhausting the air, insert them into the rubber stopper of the reaction flask. During stirring, inject 2 mL of dry tetrahydrofuran and 2 mL of bromobenzene, heat, and then place the reaction flask in an ice bath environment. Continue to slowly inject the remaining dry tetrahydrofuran and bromobenzene. After the injection is completed, heat and stir the reaction in an oil bath at 60 °C for 3 h to obtain solution A;

[0043] S2: Add 4 g of anthraquinone into a reaction container, seal it and perform the vacuum-purging nitrogen operation, then inject 170 mL of dry tetrahydrofuran. Cool down to -10 °C and react for 30 min. Then, slowly inject 72.5 mL of solution A into the reaction container using a syringe. Stir and react at 0 °C for 4 h. Then, slowly dropwise add a saturated ammonium chloride aqueous solution to quench the reaction. Perform rotary evaporation, extraction, collect the organic phase, dry, concentrate by rotary evaporation, purify, and recrystallize to obtain product B;

[0044] S3: Add 2.18 g of product B, 1.11 g of 4,4'-difluorobenzophenone, 7.8 mL of sulfolane, 0.83 g of potassium carbonate, and 11 mL of toluene into a container. Under nitrogen protection, heat and react. The reaction process is as follows: maintain at 140 °C for 1 h, 160 °C for 1 h, 180 °C for 1 h, and 190 °C for 3 h. After the reaction ends, pulverize and boil-wash to obtain a polymer. Add 10.5 g of the polymer into 22.5 mL of ethanol, stir and mix evenly, then add 1.12 g of polyethylene glycol, and perform ball milling to obtain a modified polymer solution.

[0045] This embodiment discloses a method for preparing a Ni-Ti shape memory alloy for an endoscopic lithotripsy basket, which includes the following steps:

[0046] Step 1: Add high-purity nickel and titanium into a melting furnace for melting. During the melting process, evacuate to ≤10 - 3 Pa, introduce argon, and the temperature is 1500 °C. Repeat the melting operation 5 times. After the melting ends, cool down, remove the surface layer substances, perform homogenization annealing at 1100 °C for 24 h, hot roll at 850 °C, and perform water quenching to obtain a Ni-Ti alloy matrix;

[0047] Step 2: Add 15 g of modified carbon nanotubes into 50 mL of absolute ethanol, perform ultrasonic dispersion at 45 °C for 30 min to obtain a suspension. Perform cold rolling treatment on the Ni-Ti alloy matrix. Before each cold rolling treatment, evenly spray the suspension, repeat the treatment, perform drawing, and perform low-temperature annealing at 200 °C for 60 min, then cool down to obtain a composite Ni-Ti alloy matrix;

[0048] Step 3: Sandblast the composite nickel-titanium alloy substrate with alumina sand of 100 mesh, with the spray gun pressure of 0.45 MPa, the spraying angle of 90°, and the spraying distance of 100 mm. Then, ultrasonically clean it with acetone, ethanol, and deionized water for 15 min in sequence. Next, spray the modified polymer solution. The electrostatic spraying is used for spraying the modified polymer solution, with the spray gun voltage of 70 kV, the spraying distance of 120 mm, and the air pressure of 0.5 MPa. Then cure it, preheat at 120 °C for 10 min, keep warm at 250 °C for 30 min, keep warm at 380 °C for 60 min, and polish to obtain the nickel-titanium shape memory alloy for endoscopic lithotripsy basket.

[0049] Example 2: This example discloses a preparation method of modified carbon nanotubes, which includes the following steps:

[0050] Q1: Add 1.08 g of 4-bromo-2-nitrobenzyl alcohol to 18 mL of N,N-dimethylformamide, then add 1.12 g of 3-methylphenylboronic acid, 0.52 g of tetrakis(triphenylphosphine)palladium, and 0.98 g of sodium carbonate. Under the protection of nitrogen, heat and stir the reaction at 140 °C for 8 h. After the reaction is completed, concentrate under reduced pressure and purify to obtain Intermediate 1.

[0051] Q2: Under a CO2 atmosphere, add 0.42 g of Intermediate 1, 0.38 g of 4-(trifluoromethyl)benzylamine, and 35 mL of tetrahydrofuran to a transparent container, irradiate with a 28 W ultraviolet lamp (wavelength 360 nm), and catalytically stir the reaction at room temperature for 24 h. After the reaction is completed, transfer it to a rotary evaporation flask, add silica gel powder, reduce the pressure, separate and purify, and wash to obtain Intermediate 2.

[0052] Q3: Add 1.5 g of carboxyl carbon nanotubes to 400 mL of absolute ethanol, ultrasonically disperse for 120 min, adjust the pH to 3, heat and treat in a water bath at 60 °C for 6 h, centrifuge and filter, wash, dry, and grind to obtain acid-activated carboxyl carbon nanotubes. Add 1.45 g of Intermediate 2 and 1.2 g of silane coupling agent KH-560 to a container, reflux and stir in a water bath at 130 °C for 5 h. After the stirring is completed, cool, add 15 mL of absolute ethanol, ultrasonically treat for 45 min, then add 10 mL of an absolute ethanol solution containing 1.1 g of acid-activated carboxyl carbon nanotubes, and heat and stir the reflux reaction at 85 °C for 6 h. After the reaction is completed, cool, centrifuge, wash, dry, and grind to obtain the modified carbon nanotubes.

[0053] This example discloses a preparation method of a modified polymer solution, which includes the following steps:

[0054] S1: Add 1.54 g of magnesium chips and 0.002 g of iodine grains into the reaction flask, perform the vacuum-purging nitrogen cycle operation to fill the reaction flask with nitrogen. Subsequently, suck 75 mL of dry tetrahydrofuran and 9.5 mL of bromobenzene into syringes respectively. After expelling the air, insert them into the rubber stopper of the reaction flask. During stirring, inject 2 mL of dry tetrahydrofuran and 2 mL of bromobenzene, heat, and then place the reaction flask in an ice bath environment. Continue to slowly inject the remaining dry tetrahydrofuran and bromobenzene. After the injection is completed, heat and stir the reaction in an oil bath at 60 °C for 3 h to obtain solution A;

[0055] S2: Add 5 g of anthraquinone into the reaction vessel, seal it and perform vacuum-purging nitrogen, then inject 190 mL of dry tetrahydrofuran. Cool down the reaction to -10 °C for 30 min, and then slowly inject 70 mL of solution A into the reaction vessel using a syringe. Stir the reaction at 0 °C for 4 h, and then slowly add saturated ammonium chloride aqueous solution to quench the reaction. Perform rotary evaporation, extraction, collect the organic phase, dry, concentrate by rotary evaporation, purify, and recrystallize to obtain product B;

[0056] S3: Add 2.01 g of product B, 0.92 g of 4,4'-difluorobenzophenone, 7.5 mL of sulfolane, 0.86 g of potassium carbonate and 10 mL of toluene into the container. Under nitrogen protection, heat and react. The reaction process is as follows: maintain at 140 °C for 1 h, 160 °C for 1 h, 180 °C for 1 h, 190 °C for 3 h. After the reaction is completed, crush and boil-wash to obtain the polymer. Add 8 g of the polymer into 25 mL of ethanol, stir and mix evenly, then add 1.25 g of polyethylene glycol, and perform ball milling to obtain the modified polymer solution.

[0057] This example discloses a preparation method of a nickel-titanium shape memory alloy for an endoscopic lithotripsy basket, including the following steps:

[0058] Step 1: Add high-purity nickel and titanium into the melting furnace for melting. During the melting process, evacuate to ≤10 - 3 Pa, introduce argon gas, the temperature is 1500 °C, repeat the melting operation 5 times. After the melting is completed, cool down, remove the surface substances, perform homogenization annealing at 1100 °C for 24 h, hot roll at 850 °C, and water quench to obtain the nickel-titanium alloy matrix;

[0059] Step 2: Add 10 g of modified carbon nanotubes into 55 mL of absolute ethanol, perform ultrasonic dispersion at 45 °C for 30 min to obtain a suspension. Perform cold rolling treatment on the nickel-titanium alloy matrix. Before each cold rolling treatment, evenly spray the suspension, repeat the treatment, perform drawing, and perform low-temperature annealing at 200 °C for 60 min, then cool down to obtain the composite nickel-titanium alloy matrix;

[0060] Step 3: Sandblast the composite nickel-titanium alloy substrate using alumina sand with 100 mesh, a spray gun pressure of 0.45 MPa, a spraying angle of 90°, and a spraying distance of 100 mm. Then, ultrasonically clean it with acetone, ethanol, and deionized water for 15 min in sequence. Next, spray the modified polymer solution. Electrostatic spraying is used for spraying the modified polymer solution, with a spray gun voltage of 70 kV, a spraying distance of 120 mm, and an air pressure of 0.5 MPa. Cure it by preheating at 120 °C for 10 min, holding at 250 °C for 30 min, and holding at 380 °C for 60 min. Then, polish it to obtain the nickel-titanium shape memory alloy for endoscopic lithotripsy baskets.

[0061] Example 3: This example discloses a preparation method of modified carbon nanotubes, which includes the following steps:

[0062] Q1: Add 1.24 g of 4-bromo-2-nitrobenzyl alcohol to 24 mL of N,N-dimethylformamide, then add 1.58 g of 3-methylphenylboronic acid, 0.63 g of tetrakis(triphenylphosphine)palladium, and 1.13 g of sodium carbonate. Under nitrogen protection, heat and stir the reaction at 140 °C for 8 h. After the reaction ends, concentrate under reduced pressure and purify to obtain Intermediate 1.

[0063] Q2: Under a CO2 atmosphere, add 0.54 g of Intermediate 1, 0.46 g of 4-(trifluoromethyl)benzylamine, and 45 mL of tetrahydrofuran to a transparent container. Irradiate it with a 28 W ultraviolet lamp (wavelength 360 nm) and catalytically stir the reaction at room temperature for 24 h. After the reaction ends, transfer it to a rotary evaporation flask, add silica gel powder, reduce the pressure, separate and purify, and wash to obtain Intermediate 2.

[0064] Q3: Add 1 g of carboxyl carbon nanotubes to 600 mL of absolute ethanol, ultrasonically disperse for 120 min, adjust the pH to 3, heat and treat in a water bath at 60 °C for 6 h, centrifuge and filter, wash, dry, and grind to obtain acid-activated carboxyl carbon nanotubes. Add 1.87 g of Intermediate 2 and 0.8 g of silane coupling agent KH-560 to a container, reflux and stir in a water bath at 130 °C for 5 h. After stirring ends, cool, add 15 mL of absolute ethanol, ultrasonically treat for 45 min, then add 10 mL of an absolute ethanol solution containing 1.5 g of acid-activated carboxyl carbon nanotubes, and heat and stir and reflux the reaction at 85 °C for 6 h. After the reaction ends, cool, centrifuge, wash, dry, and grind to obtain the modified carbon nanotubes.

[0065] This example discloses a preparation method of a modified polymer solution, which includes the following steps:

[0066] S1: Add 1.92 g of magnesium chips and 0.003 g of iodine grains into the reaction flask. Conduct the vacuum-purging nitrogen circulation operation to fill the reaction flask with nitrogen. Subsequently, suck 70 mL of dry tetrahydrofuran and 5.5 mL of bromobenzene into syringes respectively. After exhausting the air, insert them into the rubber stopper of the reaction flask. During stirring, inject 2 mL of dry tetrahydrofuran and 2 mL of bromobenzene. Heat, and then place the reaction flask in an ice bath environment. Continue to slowly inject the remaining dry tetrahydrofuran and bromobenzene. After injection, heat and stir the reaction at 60 °C for 3 h to obtain solution A;

[0067] S2: Add 3 g of anthraquinone into the reaction vessel. Seal it and conduct the vacuum-purging nitrogen operation, then inject 150 mL of dry tetrahydrofuran. Cool the reaction to -10 °C for 30 min. Then, slowly inject 75 mL of solution A into the reaction vessel using a syringe. Stir the reaction at 0 °C for 4 h. Then, slowly add saturated ammonium chloride aqueous solution to quench the reaction. Rotate and evaporate, extract, collect the organic phase, dry, rotate and concentrate, purify, and recrystallize to obtain product B;

[0068] S3: Add 2.35 g of product B, 1.21 g of 4,4'-difluorobenzophenone, 8.1 mL of sulfolane, 0.8 g of potassium carbonate, and 12 mL of toluene into the container. Under nitrogen protection, heat and react. The reaction process is as follows: maintain at 140 °C for 1 h, 160 °C for 1 h, 180 °C for 1 h, and 190 °C for 3 h. After the reaction ends, crush and boil and wash to obtain the polymer. Add 13 g of the polymer into 20 mL of ethanol, stir and mix evenly, then add 1 g of polyethylene glycol, and ball mill to obtain the modified polymer solution.

[0069] This example discloses a preparation method of a nickel-titanium shape memory alloy for an endoscopic stone extraction basket, including the following steps:

[0070] Step 1: Add high-purity nickel and titanium into the melting furnace for melting. During the melting process, evacuate to ≤10 - 3 Pa, introduce argon, and the temperature is 1500 °C. Repeat the melting operation 5 times. After melting, cool, remove the surface layer substances, conduct homogenization annealing at 1100 °C for 24 h, hot roll at 850 °C, and water quench to obtain the nickel-titanium alloy matrix;

[0071] Step 2: Add 20 g of modified carbon nanotubes into 45 mL of absolute ethanol, ultrasonically disperse at 45 °C for 30 min to obtain a suspension. Conduct cold rolling treatment on the nickel-titanium alloy matrix. Before each cold rolling treatment, evenly spray the suspension, repeat the treatment, draw, conduct low-temperature annealing at 200 °C for 60 min, and cool to obtain the composite nickel-titanium alloy matrix;

[0072] Step 3: Sandblast the composite nickel-titanium alloy substrate using alumina sand with 100 mesh, the spray gun pressure is 0.45 MPa, the spraying angle is 90°, the spraying distance is 100 mm, ultrasonically clean it with acetone, ethanol, and deionized water in sequence for 15 min, then spray the modified polymer solution. The spraying of the modified polymer solution uses electrostatic spraying, the spray gun voltage is 70 kV, the spraying distance is 120 mm, the air pressure is 0.5 MPa, cure it, preheat at 120 °C for 10 min, keep it warm at 250 °C for 30 min, keep it warm at 380 °C for 60 min, and polish to obtain the nickel-titanium shape memory alloy for endoscopic lithotripsy basket.

[0073] Example 4: This example discloses a preparation method of modified carbon nanotubes, which includes the following steps:

[0074] Q1: Add 1.12 g of 4-bromo-2-nitrobenzyl alcohol to 19 mL of N,N-dimethylformamide, then add 1.23 g of 3-methylphenylboronic acid, 0.54 g of tetrakis(triphenylphosphine)palladium, and 1.02 g of sodium carbonate. Under nitrogen protection, heat and stir the reaction at 140 °C for 8 h. After the reaction is completed, concentrate under reduced pressure and purify to obtain Intermediate 1;

[0075] Q2: Under a CO2 atmosphere, add 0.45 g of Intermediate 1, 0.4 g of 4-(trifluoromethyl)benzylamine, and 37 mL of tetrahydrofuran to a transparent container, irradiate with a 28 W ultraviolet lamp (wavelength 360 nm), and catalytically stir the reaction at room temperature for 24 h. After the reaction is completed, transfer it to a rotary evaporation flask, add silica gel powder, reduce the pressure, separate and purify, and wash to obtain Intermediate 2;

[0076] Q3: Add 1.1 g of carboxyl carbon nanotubes to 450 mL of absolute ethanol, ultrasonically disperse for 120 min, adjust the pH = 3, heat and treat in a water bath at 60 °C for 6 h, centrifuge and filter, wash, dry, and grind to obtain acid-activated carboxyl carbon nanotubes. Add 1.53 g of Intermediate 2 and 0.9 g of silane coupling agent KH-560 to a container, reflux and stir in a water bath at 130 °C for 5 h. After stirring is completed, cool, add 15 mL of absolute ethanol, ultrasonically treat for 45 min, then add 10 mL of an absolute ethanol solution containing 1.4 g of acid-activated carboxyl carbon nanotubes, heat and stir and reflux the reaction at 85 °C for 6 h. After the reaction is completed, cool, centrifuge, wash, dry, and grind to obtain modified carbon nanotubes.

[0077] This example discloses a preparation method of a modified polymer solution, which includes the following steps:

[0078] S1: Add 1.61 g of magnesium shavings and 0.0028 g of iodine grains into the reaction flask. Perform the evacuation-nitrogen purging cycle operation to fill the reaction flask with nitrogen. Subsequently, suck 71 mL of dry tetrahydrofuran and 8 mL of bromobenzene into syringes respectively. After expelling the air, insert them into the rubber stopper of the reaction flask. During stirring, inject 2 mL of dry tetrahydrofuran and 2 mL of bromobenzene. Heat, and then place the reaction flask in an ice bath environment. Continue to slowly inject the remaining dry tetrahydrofuran and bromobenzene. After the injection is completed, heat and stir the reaction at 60 °C for 3 h to obtain solution A.

[0079] S2: Add 3.5 g of anthraquinone into the reaction vessel. Seal it and perform evacuation-nitrogen purging, then inject 160 mL of dry tetrahydrofuran. Cool the reaction to -10 °C for 30 min, and then slowly inject 71 mL of solution A into the reaction vessel using a syringe. Stir the reaction at 0 °C for 4 h, then slowly add saturated ammonium chloride aqueous solution to quench the reaction. Perform rotary evaporation, extraction, collect the organic phase, dry it, concentrate by rotary evaporation, purify, and recrystallize to obtain product B.

[0080] S3: Add 2.09 g of product B, 0.98 g of 4,4'-difluorobenzophenone, 7.6 mL of sulfolane, 0.81 g of potassium carbonate, and 10.5 mL of toluene into the container. Under nitrogen protection, heat and react. The reaction process is as follows: maintain at 140 °C for 1 h, 160 °C for 1 h, 180 °C for 1 h, and 190 °C for 3 h. After the reaction is completed, pulverize and wash by boiling to obtain the polymer. Add 11 g of the polymer into 21 mL of ethanol, stir and mix evenly, then add 1.08 g of polyethylene glycol, and perform ball milling to obtain the modified polymer solution.

[0081] This example discloses a preparation method of a nickel-titanium shape memory alloy for an endoscopic stone retrieval basket, including the following steps:

[0082] Step 1: Add high-purity nickel and titanium into the melting furnace for melting. During the melting process, evacuate to ≤10 - 3 Pa, introduce argon gas, and the temperature is 1500 °C. Repeat the melting operation 5 times. After the melting is completed, cool, remove the surface layer substances, perform homogenization annealing at 1100 °C for 24 h, hot roll at 850 °C, and water quench to obtain the nickel-titanium alloy matrix.

[0083] Step 2: Add 12 g of modified carbon nanotubes into 48 mL of absolute ethanol, ultrasonically disperse at 45 °C for 30 min to obtain a suspension. Perform cold rolling treatment on the nickel-titanium alloy matrix. Before each cold rolling treatment, evenly spray the suspension, repeat the treatment, draw, perform low-temperature annealing at 200 °C for 60 min, and cool to obtain the composite nickel-titanium alloy matrix.

[0084] Step 3: Sandblast the composite nickel-titanium alloy substrate using alumina sand with 100 mesh, the spray gun pressure is 0.45 MPa, the spraying angle is 90°, the spraying distance is 100 mm, ultrasonically clean it with acetone, ethanol, and deionized water in sequence for 15 min, and then spray the modified polymer solution. Electrostatic spraying is used for spraying the modified polymer solution, the spray gun voltage is 70 kV, the spraying distance is 120 mm, the air pressure is 0.5 MPa, cure it, preheat at 120 °C for 10 min, keep it warm at 250 °C for 30 min, keep it warm at 380 °C for 60 min, and polish it to obtain the nickel-titanium shape memory alloy for endoscopic lithotripsy basket.

[0085] Comparative Example 1: Compared with Example 1, in the process of preparing the nickel-titanium shape memory alloy for endoscopic lithotripsy basket in Comparative Example 1, modified carbon nanotubes are not added, and other conditions remain unchanged.

[0086] Comparative Example 2: Compared with Example 1, in the process of preparing the nickel-titanium shape memory alloy for endoscopic lithotripsy basket in Comparative Example 2, the modified polymer solution is not sprayed, and other conditions remain unchanged.

[0087] Experimental Example: Perform performance tests on the nickel-titanium shape memory alloys for endoscopic lithotripsy basket prepared in Examples 1-4 and Comparative Examples 1-2. Test the mechanical properties of the samples according to GB / T 228.1-2010, and test the corrosion resistance of the samples according to GB / T10125-2012. The results are shown in Table 1:

[0088] Table 1

[0089] project Yield strength / MPa Elongation strength / MPa Mass reduction rate / % Example 1 487 679 0.043 Example 2 481 673 0.046 Example 3 475 668 0.051 Example 4 477 664 0.053 Comparative Example 1 425 611 0.098 Comparative Example 2 421 607 0.055

[0090] It can be seen from the test results in Table 1 that the shape memory alloys prepared in Examples 1-4 of the present invention have excellent mechanical properties and corrosion resistance. By comparing Comparative Example 1 with Examples 1-4, it can be known that adding modified carbon nanotubes can effectively improve the mechanical properties and corrosion resistance of the shape memory alloy; by comparing Comparative Example 2 with Examples 1-4, it can be known that spraying the modified polymer solution can effectively improve the mechanical properties of the shape memory alloy.

[0091] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

[0092] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments only. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing a nickel-titanium shape memory alloy for an endoscopic stone removal basket, characterized in that: The following steps are involved: Step 1: adding high-purity nickel and titanium into a smelting furnace for smelting, cooling after smelting, removing the surface material, homogenizing annealing, hot rolling, and water quenching to obtain a nickel-titanium alloy matrix; Step 2: adding the modified carbon nanotubes to anhydrous ethanol, ultrasonically dispersing to obtain a suspension, cold-rolling the nickel-titanium alloy substrate, uniformly spraying the suspension before each cold-rolling treatment, repeating the treatment, drawing, low-temperature annealing, and cooling to obtain a composite nickel-titanium alloy substrate; Step 3: sandblasting the composite nickel-titanium alloy substrate, ultrasonic cleaning, spraying the modified polymer solution, curing, and polishing to obtain the nickel-titanium shape memory alloy for the endoscopic stone removal basket.

2. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 1, characterized in that: In the step 1, during the smelting process, the vacuum is drawn to ≤10 -3 Pa, introduce argon, the temperature is 1500-1600℃, repeat the smelting operation 3-5 times, the homogenization annealing temperature is 1000-1100℃, keep warm for 12-24h, and the hot rolling temperature is 800-950℃.

3. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 1, characterized in that: In the step 2, the usage ratio of modified carbon nanotubes and anhydrous ethanol is (10-20) g: (45-55) mL, the ultrasonic dispersion temperature is 40-45° C., the time is 30-45 min, the low-temperature annealing temperature is 200-300° C., and the insulation time is 30-60 min.

4. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 1, characterized in that: In the step three, in the sandblasting treatment, 80-120 mesh alumina sand is used, the spray gun pressure is 0.4-0.6 MPa, the spray angle is 90°, the spraying distance is 90-100 mm, and ultrasonic cleaning is carried out with acetone, ethanol, and deionized water for 15 minutes in sequence. The modified polymer solution is sprayed by electrostatic spraying, the spray gun voltage is 60-80 kV, the spraying distance is 100-150 mm, the air pressure is 0.3-0.5 MPa, and the curing process is: preheating at 120°C for 10 minutes, keeping warm at 250°C for 30 minutes, and keeping warm at 380°C for 60 minutes.

5. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 1, characterized in that: The preparation method of the modified carbon nanotubes, The following steps are involved: Q1: Add 4-bromo-2-nitrobenzyl alcohol to N,N-dimethylformamide, then add 3-methylphenylboric acid, tetrakis(triphenylphosphine)palladium and sodium carbonate, and heat and stir to react under nitrogen protection. After the reaction is completed, concentrate under reduced pressure and purify to obtain intermediate 1; Q2: Under CO2 atmosphere, intermediate 1, 4-(trifluoromethyl)benzylamine and tetrahydrofuran were added to a transparent container, irradiated with ultraviolet light, and catalytically stirred at room temperature for reaction. After the reaction was completed, the mixture was transferred to a rotary evaporator, silica gel powder was added, the pressure was reduced, separated and purified, and washed to obtain intermediate 2; Q3: Add carboxyl carbon nanotubes to anhydrous ethanol, disperse with ultrasound, adjust the pH, heat in a water bath, centrifuge, filter, wash, dry, and grind to obtain acid-activated carboxyl carbon nanotubes. Add intermediate 2 and silane coupling agent KH-560 to a container, reflux with stirring in a water bath, cool after stirring, add anhydrous ethanol, treat with ultrasound, then add anhydrous ethanol solution containing acid-activated carboxyl carbon nanotubes, heat and stir under reflux to react, cool, centrifuge, wash, dry, and grind to obtain modified carbon nanotubes.

6. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 5, characterized in that: In the Q1, the amount ratio of 4-bromo-2-nitrobenzyl alcohol, N,N-dimethylformamide, 3-methylphenylboric acid, tetrakis(triphenylphosphine)palladium and sodium carbonate is (1.08-1.24) g: (18-24) mL: (1.12-1.58) g: (0.52-0.63) g: (0.98-1.13) g, the heating and stirring reaction temperature is 130-150° C., and the reaction time is 8-10 h. In the Q2, the amount ratio of the intermediate 1, 4-(trifluoromethyl)benzylamine and tetrahydrofuran is (0.42-0.54) g: (0.38-0.46) g: (35-45) mL, the ultraviolet lamp power is 24-28 W, the ultraviolet lamp wavelength is 350-380 nm, and the stirring reaction time is 20-28 h.

7. The method for preparing the nickel-titanium shape memory alloy for an endoscopic stone removal basket according to claim 5, characterized in that: In the Q3, the dosage ratio of carboxyl carbon nanotubes and anhydrous ethanol is (1-1.5) g: (400-600) mL, the ultrasonic dispersion time is 120-150 min, the pH is adjusted to 3-4, the water bath heating treatment temperature is 50-60°C, and the treatment time is 6-8 h. The dosage ratio of intermediate 2, silane coupling agent KH-560 and acid-activated carboxyl carbon nanotubes is (1.45-1.87) g: (0.8-1.2) g: (1.1-1.5) g, the water bath reflux stirring temperature is 130-150°C, the stirring time is 3-5 h, the ultrasonic treatment time is 30-45 min, the heating stirring reflux reaction temperature is 80-85°C, and the reaction time is 6-8 h.

8. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 1, characterized in that: The method for preparing the modified polymer solution comprises the following steps: S1: Add magnesium chips and iodine particles to a reaction bottle, perform a vacuum-nitrogen blowing cycle to fill the reaction bottle with nitrogen, then suck dry tetrahydrofuran and bromobenzene into syringes respectively, and insert the syringes into the rubber stopper of the reaction bottle after exhausting the air. Inject dry tetrahydrofuran and bromobenzene during stirring, heat, and then place the reaction bottle in an ice bath environment, and continue to slowly inject dry tetrahydrofuran and bromobenzene. After the injection is completed, heat and stir the reaction in an oil bath to obtain solution A; S2: Add anthraquinone to a reaction container, seal it, evacuate it, and then inject dry tetrahydrofuran, cool it down to react, then slowly inject solution A into the reaction container using a syringe, stir it at low temperature to react, then slowly drop saturated ammonium chloride aqueous solution to quench the reaction, rotary evaporate, extract, collect the organic phase, dry, rotary evaporate and concentrate, purify, and recrystallize to obtain product B; S3: Add product B, 4,4'-difluorobenzophenone, cyclopentane sulfone, potassium carbonate and toluene into a container, heat and react under nitrogen protection, crush and boil to obtain a polymer after the reaction is completed, add the polymer into ethanol, stir and mix well, add polyethylene glycol, and ball mill to obtain a modified polymer solution.

9. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 8, characterized in that: In the S1, the amount ratio of magnesium chips, iodine particles, dry tetrahydrofuran and bromobenzene is (1.54-1.92) g: (0.002-0.003) g: (70-75) mL: (5.5-9.5) mL, the oil bath heating and stirring reaction temperature is 55-65°C, and the reaction time is 3-5 h; in the S2, the amount ratio of anthraquinone, dry tetrahydrofuran and solution A is (3-5) g: (150-190) mL: (70-75) mL, the cooling reaction temperature is -8 to -10°C, the reaction time is 20-30 min, and the low temperature stirring reaction temperature is -1 to 0°C, and the reaction time is 4-6 h.

10. The method for preparing the nickel-titanium shape memory alloy for endoscopic stone removal basket according to claim 8, characterized in that: In S3, the amount ratio of product B, 4,4'-difluorobenzophenone, cyclopentane sulfone, potassium carbonate and toluene is (2.01-2.35) g: (0.92-1.21) g: (7.5-8.1) mL: (0.8-0.86) g: (10-12) mL, the heating reaction process is: 140°C for 1 hour, 160°C for 1 hour, 180°C for 1 hour, 190°C for 3 hours, and the amount ratio of polymer, ethanol and polyethylene glycol is (8-13) g: (20-25) mL: (1-1.25) g.

11. A nickel-titanium shape memory alloy for an endoscopic stone removal basket prepared by the method according to any one of claims 1 to 10.

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