CN113275593B - Method for preparing porous Ta/Ti-6Al-4V integrated piece through selective laser melting - Google Patents

Abstract

The invention relates to a method for preparing a porous Ta/Ti-6Al-4V integrated piece with bonding strength by selective laser melting, belonging to the technical field of metal material additive manufacturing. The invention relates to a method for preparing a porous Ta/Ti-6Al-4V integrated member by selective laser melting, which comprises the following steps: step one, preparing a Ti-6Al-4V alloy matrix according to a set shape and size; secondly, tantalum powder is used as a raw material, and a Ta coating is prepared on the Ti-6Al-4V alloy substrate through SLM; the technological parameters of the SLM are set as follows: the diameter of the laser spot is 110 μm, the laser power is 200-400W, the laser scanning speed is 200-600 mm/s, the laser scanning interval is 100-. The method has the advantages of simple and reasonable process, high production efficiency and excellent mechanical property of the obtained porous Ta/Ti-6Al-4V integrated piece.

Description

Method for preparing porous Ta/Ti-6Al-4V integrated piece by selective laser melting

Technical Field

The invention relates to a method for preparing a porous Ta/Ti-6Al-4V integrated piece with bonding strength by selective laser melting, belonging to the technical field of metal material additive manufacturing.

Background

Biomedical materials are fundamental to the development of modern clinical medicine, with medical metallic materials being widely used in surgical implants and orthopedic devices. At present, medical metal materials mainly comprise three series of medical stainless steel, cobalt-based alloy and titanium alloy, wherein the titanium alloy has the characteristics of small specific gravity, high specific strength, low elastic modulus, easiness in processing and forming, rich raw material resources and the like, and can be used as an ideal functional structure material of surgical implants. However, the metal implant is easy to cause the release of toxic elements in a complex human body environment, the biocompatibility is reduced, and meanwhile, the elastic modulus of the metal material is too large to be different from that of human bone tissues, so that the stress shielding effect is easy to generate, the adverse effect on the growth and remodeling of new bones is generated, even the implant is failed, and secondary fracture is caused. Therefore, people are dedicated to search for a metal implant material with better corrosion resistance and biocompatibility, and search for mechanical properties closer to human bones through structural design.

Metallic tantalum (Ta) is widely spotlighted in the industry due to its unique advantages of excellent corrosion resistance, good biocompatibility, etc., but its wide application is limited by the high raw material cost. Developing new alloys or adding alloying elements to improve their biological properties is an effective method, but for cost reasons, preparing coatings is a more straightforward and simple process. The existing research results show that the corrosion resistance of the thick and compact tantalum coating can reach the level of bulk tantalum materials. Therefore, the preparation of a dense tantalum coating with a certain thickness has been the hot spot of tantalum application research.

At present, the main methods for preparing tantalum coatings at home and abroad include a molten salt electroplating method, a plasma spraying method, a magnetron sputtering method, ion beam assisted deposition, chemical vapor deposition, direct current diode sputtering ion implantation and the like. However, because tantalum has the characteristics of high melting point, high oxygen affinity and the like, obtaining a porous Ta/Ti-6Al-4V integrated piece with good bonding force between a substrate and a coating and high film forming quality is still a great problem. The development of Selective Laser Melting (SLM) provides technical conditions for conveniently preparing the tantalum coating with a controllable porous structure, and the elastic modulus of the porous tantalum coating can be matched with that of human bones by designing the porosity and the pore diameter of a porous matrix and controlling the porosity and the pore diameter; and then manufacturing the three-dimensional solid part under computer aided design and control by using the manufacturing principle of material accumulation. The SLM technology has the characteristics of short part development period, high machining precision, raw material saving, capability of forming any complex part and the like. Currently, this technique has been used to form a variety of metals such as titanium alloys, stainless steels, aluminum alloys, nickel-base superalloys, and the like. Even refractory metals such as Mo, Ta, W, etc. can be formed by a high energy density laser. Therefore, the selective laser melting technology is adopted to prepare the porous Ta/Ti-6Al-4V integrated piece with high bonding strength, and is a novel method with high feasibility. However, until now, no report is available about the preparation of Ta coating on Ti-6Al-4V substrate by SLM technology.

Disclosure of Invention

Aiming at the defect that the porous tantalum coating with a complex structure cannot be prepared by the traditional powder metallurgy technology, the invention aims to provide a method for preparing the complex porous tantalum coating by utilizing selective laser melting, realizing the metallurgical bonding of a Ti-6Al-4V substrate and the porous tantalum coating and greatly improving the mechanical property of a porous Ta/Ti-6Al-4V integrated part prepared by selective laser melting. On one hand, the porous Ta coating is prepared on the Ti-6Al-4V substrate, and the performance advantage of the Ti-6Al-4V substrate is utilized; on the other hand, the characteristic of good biocompatibility of the metal tantalum is exerted, and the high cost of completely using the metal tantalum is reduced. The porous Ta/Ti-6Al-4V integrated piece with high interface bonding strength is prepared by a selective melting technology.

The purpose of the invention can be realized by the following technical scheme:

a method for preparing a porous Ta/Ti-6Al-4V integrated member by selective laser melting comprises the following steps:

step one

Preparing a Ti-6Al-4V alloy matrix according to a set shape and size;

step two

Tantalum powder is used as a raw material, and a Ta coating is prepared on a Ti-6Al-4V alloy matrix through SLM (selective laser melting); the technological parameters of the SLM are set as follows: the diameter of a laser spot is 110 μm, the laser power is 280-320W, the laser scanning speed is 230-270 mm/s, the laser scanning interval is 100-.

As a preferable scheme, in the method for preparing the porous Ta/Ti-6Al-4V integrated member by selective laser melting, in the step one, the Ti-6Al-4V alloy substrate is prepared by 3D printing. When the Ti-6Al-4V alloy matrix is prepared by 3D printing, the printing parameters are controlled as follows: the diameter of the laser spot is 110 μm, the laser power is 200-800W, the laser scanning speed is 300-1000 mm/s, the laser scanning interval is 100-.

According to the method for preparing the porous Ta/Ti-6Al-4V integrated member by selective laser melting, when a Ti-6Al-4V alloy matrix is prepared by 3D printing, the particle size range of Ti-6Al-4V alloy powder is 5-87 micrometers, and the D50 is 36-70 micrometers, preferably 38.7 micrometers.

The invention relates to a method for preparing a porous Ta/Ti-6Al-4V integrated piece by selective laser melting, which is used when a Ti-6Al-4V alloy matrix is prepared by 3D printing; the method comprises the following steps:

step A

Constructing a part model to be prepared by using three-dimensional software Magics, and guiding the constructed model into selective laser melting molding equipment;

step B

Firstly, placing the sieved Ti-6Al-4V alloy powder into a powder supply cylinder in selective laser melting equipment, and simultaneously introducing protective gas (Ar gas) into a forming cavity for atmosphere protection.

Step C

Setting technological parameters of the selective laser melting processing process, and carrying out laser sintering on the Ti-6Al-4V alloy powder.

After the printing of the Ti-6Al-4V substrate is finished, respectively collecting residual Ti-6Al-4V powder in the forming cylinder and the powder supply cylinder; subsequently, printing of porous Ta coatings was continued on Ti-6Al-4V substrates.

As a preferred scheme, the invention relates to a method for preparing a porous Ta/Ti-6Al-4V integrated member by selective laser melting, wherein tantalum powder is spherical tantalum powder; the particle size of the spherical tantalum powder is 2.42-76 mu m, and the D50 is 14.4 mu m.

The spherical tantalum powder is prepared from metal tantalum powder serving as a raw material by a plasma spheroidizing technology. According to an advantageous embodiment of the invention, the raw tantalum powder is spheroidized using a plasma. During the spheroidization process, the agglomerated or irregularly shaped powder particles can be remelted and then formed into spherical droplets by centrifugal force and surface tension and rapidly solidified into powder particles in a solidification bin. The spheroidized powder has a spherical shape, thereby having excellent fluidity. The spheroidized powder particles are collected by a collecting bin below the instrument. The spheroidized powder was then sieved and then placed in a vacuum oven to dry for further experiments.

The particle size of the raw material metal tantalum powder is 2.42-100 μm, and D50 is 10-20 μm, preferably 10-15 μm.

As a preferred scheme, the invention relates to a method for preparing a porous Ta/Ti-6Al-4V integrated piece by selective laser melting, and in the second step, the technological parameters of an SLM are set as follows: the laser spot diameter is 110 μm, the laser power is 300W, the scanning speed is 250mm/s, the scanning interval is 100 μm, the thickness of a single-layer powder laying layer is 30 μm, and the scanning path is 67 degrees of rotation between adjacent layers. In the invention, the product with excellent performance can be prepared only by adopting the laser power of 300W, the scanning speed of 250mm/s, the scanning interval of 100 mu m and the thickness of a single-layer powder laying layer of 30 mu m, and when the printing parameters are matched with the structure and parameters of the bracket, the performance of the obtained product is further improved.

When in application, firstly, placing spheroidized Ta powder into a powder supply cylinder in selective laser melting equipment, and simultaneously introducing protective gas (Ar gas) into a forming cavity for atmosphere protection; and then according to the set technological parameters of the selective laser melting processing process, introducing a designed porous diamond structure file, and performing laser sintering on the spherical tantalum powder. (the spherical tantalum powder is preferably pure tantalum powder).

Preferably, in the SLM processing process, argon is introduced into the forming cavity to serve as protective gas, so that the oxygen content in the forming cavity is less than 0.1%.

Preferably, the substrate heating temperature is set to 100 ℃.

The tantalum layer is distributed in a porous mode. According to the scheme of the invention, the compressive yield strength of the obtained tantalum layer is 6 MPa-27 MPa, and the elastic modulus is 0.6 GPa-1.5 GPa.

The porous Ta/Ti-6Al-4V integrated component realizes metallurgical bonding at the interface of a substrate and a coating, shows higher bonding strength, and has the bonding strength of 90-460MPa, and the bonding strength can be optimally 460MPa after optimization.

In the invention, when the bracket adopts a diamond structure, the size of a single bag is 2.0mm multiplied by 2.0mm, the size of the bracket is 0.478mm, the aperture is 0.865mm, and the porosity is 70 percent; the mechanical properties of the tantalum layer are as follows: sigma_u(compressive strength) 27.85. + -. 4.33MPa, Sigma_0.2The compressive yield strength (compressive yield strength) is 24.19 +/-4.12 MPa, and the E (elastic modulus) is 1.49 +/-0.11 GPa.

The method for preparing the porous Ta/Ti-6Al-4V integrated piece by selective laser melting provided by the invention is characterized in that irregular tantalum powder is spheroidized by the plasma spheroidizing method, and then selective laser melting is carried out. The method for preparing the porous Ta/Ti-6Al-4V integrated piece by selective laser melting has simple and reasonable process and high production efficiency, and provides a method for preparing the porous Ta/Ti-6Al-4V integrated piece and effectively improving the mechanical property of the integrated piece.

Drawings

FIG. 1 is a schematic representation of a porous Ta/Ti-6Al-4V integral member obtained in example 1;

FIG. 2 is a confocal FDA/PI staining of MC3T3-E1 cells cultured on a porous Ta/Ti-6Al-4V integration construct obtained in example 1 for 3 days.

FIG. 3 is a surface topography of a solid Ta obtained in comparative example 1;

FIG. 4 is a surface topography of the Ta/Ti-6Al-4V sample obtained in comparative example 3;

FIG. 5 is a schematic view of a pore structure in a stent according to embodiment 1;

FIG. 6 is an SEM photograph of the product obtained in example 2;

FIG. 7 is an SEM photograph of the product obtained in example 3;

FIG. 8 is an SEM photograph of the product obtained in comparative example 4;

FIG. 9 is an SEM photograph of the product obtained in comparative example 5.

The specific implementation mode is as follows:

example 1

Step one, selective laser melting of Ti-6Al-4V substrate

In example 1, the Ti-6Al-4V alloy powder had a particle size of 5 to 87 μm and D50 was 38.7. mu.m.

Then placing Ti-6Al-4V alloy powder into a powder supply cylinder of selective laser melting equipment produced by the Hua Shuo Kogyo, and performing selective laser melting printing on selected parameters: the laser spot diameter is 110 microns, the laser power is 250W, the scanning speed is 1000mm/s, the scanning interval is 250 microns, the thickness of a single-layer powder laying layer is 30 microns, the scanning path is that the adjacent layers rotate 67 degrees, argon is filled as a protective atmosphere, and laser melting is carried out on Ti-6Al-4V alloy powder. And after the laser processing is finished, respectively vacuum bagging the Ti-6Al-4V alloy powder in the forming cylinder and the powder supply cylinder. The compactness of the Ti-6Al-4V component is 99%, the tensile strength is 1260MPa, and the elastic modulus is 106 GPa.

Step two selective laser melting of porous Ta coating

In the second step, the particle size range of the irregular tantalum powder is 2.42-100 μm, and the D50 is 11.5 μm.

The method comprises the steps of taking irregular tantalum powder as a raw material, weighing 600g of pure tantalum powder, loading the pure tantalum powder into a powder feeding device of plasma spheroidizing equipment, starting the equipment, taking argon as carrier gas, feeding powder particles into a plasma region, melting the powder particles into liquid in a high-temperature environment of the plasma region, solidifying the molten particles into a spherical shape under the action of centrifugal force and surface tension in subsequent cooling, and collecting the spheroidized powder particles by a collection bin below an instrument. Then, the spheroidized powder is sieved and dried. Then placing the prepared powder in a powder supply cylinder of selective laser melting equipment produced by Huadaozhou, taking the Ti-6Al-4V matrix obtained in the step one as a substrate, and preparing a porous Ta layer on the surface of the substrate by adopting a selective laser melting technology; selecting parameters for laser melting printing: the diameter of a laser spot is 110 micrometers, the laser power is 300W, the scanning speed is 250mm/s, the scanning distance is 100 micrometers, the thickness of a single-layer powder laying layer is 30 micrometers, the scanning path is that the adjacent layers rotate by 67 degrees, argon is filled as a protective atmosphere, and the spheroidized tantalum powder is subjected to laser melting. After the laser processing is finished, the sample is subjected to linear cutting and ultrasonic cleaning. The porous Ta/Ti-6Al-4V integral member is shown in FIG. 1. The compressive yield strength of the porous tantalum bracket is 6MPa to 27MPa, and the elastic modulus is 0.6GPa to 1.5 GPa; the porous Ta/Ti-6Al-4V integrated component realizes metallurgical bonding at the interface of a substrate and a coating, and shows higher bonding strength, wherein the bonding strength is 460 MPa.

The porous structure design of the three scaffolds is shown in Table 1

TABLE 1

TABLE 2 mechanical Properties of porous tantalum

Application of the product obtained in example 1 biocompatibility of porous Ta/Ti-6Al-4V integral

The porous Ta/Ti-6Al-4V integrated material obtained in example 1 was used as the subject. Survival of MC3T3-E1 cells on porous Ta/Ti-6Al-4V integral building blocks showing good biocompatibility was examined using FDA/PI staining, as shown in FIG. 2.

Comparative example 1

Selective laser melting of Ta bulk

In the first step, the particle size range of the irregular tantalum powder is 2.42-100 μm, and the D50 is 11.5 μm.

The method comprises the steps of taking irregular tantalum powder as a raw material, weighing 600g of pure tantalum powder, loading the pure tantalum powder into a powder feeding device of plasma spheroidizing equipment, starting the equipment, taking argon as carrier gas, feeding powder particles into a plasma region, melting the powder particles into liquid in a high-temperature environment of the plasma region, solidifying the molten particles into a spherical shape under the action of centrifugal force and surface tension in subsequent cooling, and collecting the spheroidized powder particles by a collection bin below an instrument. Then, the spheroidized powder is sieved and dried. Then placing the prepared powder in a powder supply cylinder of selective laser melting equipment produced by the Huaeosin high-tech, and depositing bulk tantalum on the surface of the substrate by adopting a selective laser melting technology; selecting parameters for laser melting printing: the diameter of a laser spot is 110 micrometers, the laser power is 100W, the scanning speed is 500mm/s, the scanning distance is 100 micrometers, the thickness of a single-layer powder laying layer is 30 micrometers, the scanning path is that the adjacent layers rotate by 67 degrees, and argon is filled as a protective atmosphere. After the laser processing is finished, the sample is subjected to linear cutting and ultrasonic cleaning. The microstructure of the bulk Ta is shown in fig. 3. The tantalum block is deposited under the optimized parameters, and a large number of cracks and holes appear in the block.

Comparative example 2

Step one Selective laser melting of porous Ta scaffolds

In the first step, the particle size range of the irregular tantalum powder is 2.42-100 μm, and the D50 is 11.5 μm.

The method comprises the steps of taking irregular tantalum powder as a raw material, weighing 600g of pure tantalum powder, loading the powder into a powder feeding device of plasma spheroidizing equipment, starting the equipment, taking argon as carrier gas, feeding powder particles into a plasma region, melting the powder particles into liquid in a high-temperature environment of the plasma region, solidifying the molten particles into spheres under the action of centrifugal force and surface tension in subsequent cooling, and collecting the spheroidized powder particles by a collecting bin below an instrument. Then, the spheroidized powder is sieved and dried. Then placing the prepared powder in a powder supply cylinder of selective laser melting equipment produced by the Huaeosin high-tech, and depositing porous tantalum on the surface of the substrate by adopting a selective laser melting technology; selecting parameters for laser melting printing: the diameter of a laser spot is 110 micrometers, the laser power is 100W, the scanning speed is 500mm/s, the scanning distance is 100 micrometers, the thickness of a single-layer powder laying layer is 30 micrometers, the scanning path is that the adjacent layers rotate by 67 degrees, and argon is filled as a protective atmosphere. After the laser processing is finished, the sample is subjected to linear cutting and ultrasonic cleaning. The compressive yield strength of the porous tantalum is 1-10 MPa, and the porous tantalum shows poor mechanical properties.

Comparative example 3

Step one Selective laser melting of Ti-6Al-4V substrate (same as step one of example 1)

Step two selective laser melting of porous Ta coating

In the second step, the particle size range of the irregular tantalum powder is 2.42-100 μm, and the D50 is 11.5 μm.

The method comprises the steps of taking irregular tantalum powder as a raw material, weighing 600g of pure tantalum powder, loading the pure tantalum powder into a powder feeding device of plasma spheroidizing equipment, starting the equipment, taking argon as carrier gas, feeding powder particles into a plasma region, melting the powder particles into liquid in a high-temperature environment of the plasma region, solidifying the molten particles into a spherical shape under the action of centrifugal force and surface tension in subsequent cooling, and collecting the spheroidized powder particles by a collection bin below an instrument. Then, the spheroidized powder is sieved and dried. Then placing the prepared powder in a powder supply cylinder of selective laser melting equipment produced by the Hippocrate Hua, taking the Ti-6Al-4V matrix obtained in the step one as a substrate, and preparing a Ta layer on the surface of the substrate by adopting a selective laser melting technology; selecting parameters for laser melting printing: the diameter of a laser spot is 110 micrometers, the laser power is 500W, the scanning speed is 500mm/s, the scanning distance is 100 micrometers, the thickness of a single-layer powder laying layer is 30 micrometers, the scanning path is that the adjacent layers rotate by 67 degrees, argon is filled as a protective atmosphere, and the spheroidized tantalum powder is subjected to laser melting. After the laser processing is finished, the sample is subjected to linear cutting and ultrasonic cleaning. The surface topography of the Ta/Ti-6Al-4V integrated component is shown in FIG. 4. The tantalum is spheroidized, and spheroidizing appears on the surface of the Ti-6Al-4V alloy, so that poor wettability and formability are shown.

Example 2

Other conditions were the same as in example 1; except that the power was 150W and the speed was 250mm/s when Ta was printed. The SEM image of the resulting product is shown in FIG. 6, with a small number of pores present on the surface.

Example 3

Other conditions were the same as in example 1; the difference is that when printing Ta, the power is 200W, and the speed is 250 mm/s; the SEM image of the resulting product is shown in FIG. 7, with a small number of pores present on the surface.

Comparative example 4

Comparative example 4 other conditions were the same as in example 1; the difference is that when printing Ta, the power is 250W, and the speed is 250 mm/s; the SEM image of the resulting product is shown in FIG. 8, where a large number of pores are present on the surface.

Comparative example 5

Other conditions were the same as in example 1; the difference is that when printing Ta, the power is 300W, and the speed is 200 mm/s; the SEM image of the resulting product is shown in FIG. 9, where macrocracks appear on the surface.

Claims (4)

1. A method for preparing a porous Ta/Ti-6Al-4V integrated member by selective laser melting is characterized by comprising the following steps:

step one

Preparing a Ti-6Al-4V alloy matrix according to a set shape and size;

step two

Tantalum powder is used as a raw material, and a Ta coating is prepared on a Ti-6Al-4V alloy matrix through SLM; the technological parameters of the SLM are set as follows: the diameter of a laser spot is 110 micrometers, the laser power is 300W, the laser scanning degree is 250mm/s, the laser scanning interval is 100 micrometers, the powder spreading thickness is 30 micrometers, and the scanning path is that the adjacent layers rotate for 67 degrees; the tantalum powder is spherical tantalum powder; the particle size of the spherical tantalum powder is 2.42-76 mu m, and the D50 is 14.4 mu m; the spherical tantalum powder is prepared by taking metal tantalum powder as a raw material through a plasma spheroidizing technology; wherein the particle size range of the raw material metal tantalum powder is 2.42-100 μm, and the D50 is 10-20 μm;

the compressive yield strength of the obtained tantalum layer is 6 MPa-27 MPa, and the elastic modulus is 0.6 GPa-1.5 GPa.

2. The method for preparing porous Ta/Ti-6Al-4V integrated member according to claim 1, characterized by the following steps: preparing the Ti-6Al-4V alloy matrix in the first step by 3D printing; when the Ti-6Al-4V alloy matrix is prepared by 3D printing, the printing parameters are controlled as follows: the diameter of the laser spot is 110 μm, the laser power is 200-800W, the laser scanning speed is 300-1000 mm/s, the laser scanning interval is 100-.

3. The method for preparing porous Ta/Ti-6Al-4V integrated member according to claim 2 by selective laser melting, wherein: when the Ti-6Al-4V alloy matrix is prepared by 3D printing, the particle size range of the used Ti-6Al-4V alloy powder is 5-87 micrometers, and the D50 is 36-70 micrometers.

4. The method for preparing porous Ta/Ti-6Al-4V integrated member according to claim 2 by selective laser melting, wherein: when the Ti-6Al-4V alloy matrix is prepared by 3D printing; the method comprises the following steps:

step A

Constructing a part model to be prepared by using three-dimensional software Magics, and guiding the constructed model into selective laser melting molding equipment;

step B

Firstly, placing screened Ti-6Al-4V alloy powder into a powder supply cylinder in selective laser melting equipment, and introducing protective gas into a forming cavity for atmosphere protection;

step C

Setting technological parameters of a selective laser melting processing process, and carrying out laser sintering on Ti-6Al-4V alloy powder;

after the printing of the Ti-6Al-4V substrate is finished, respectively collecting residual Ti-6Al-4V powder in the forming cylinder and the powder supply cylinder; subsequently, printing of porous Ta coatings was continued on Ti-6Al-4V substrates.

Images