A method for preparing a biomedical magnesium-based composite material without matrix metal inclusions

Abstract

The present invention discloses a method for preparing a biomedical magnesium-based composite material without matrix metal inclusions, the method comprising: 1. sequentially grooving, powder filling and grooving sealing treatments on a magnesium-based plate, and then using a large-sized stirring head to perform multiple reciprocating stirring friction processing to form a processing area to obtain a magnesium-based composite material intermediate; 2. In the processing area of ​​the magnesium-based composite material intermediate, using a small-sized stirring head to perform multiple reciprocating stirring friction processing to obtain a biomedical magnesium-based composite material without matrix metal inclusions. The present invention sequentially uses a large-sized stirring head and a small-sized stirring head to perform multiple reciprocating stirring friction processing, effectively eliminating the newly introduced matrix metal during each downward pressure, and the ceramic particles are evenly distributed to avoid matrix metal inclusions, thereby improving the corrosion performance and thermal stability of the magnesium-based composite material, making it suitable for biomedical use.

Description

Technical Field

[0001] The invention belongs to the technical field of biomedical metal-based composite materials, and in particular relates to a method for preparing a biomedical magnesium-based composite material without matrix metal inclusions. Background Art

[0002] The density, elastic modulus and other physical properties of medical magnesium and magnesium alloys are close to those of human bones. When used as orthopedic medical devices, they can better avoid stress shielding between the body's bones and are conducive to the healing of bone tissue. At the same time, the degradation performance of magnesium devices can prevent patients from undergoing secondary surgery. Their degradation products are non-biotoxic and can be excreted in the urine, and have good biocompatibility. However, medical magnesium and magnesium alloys still have shortcomings such as insufficient mechanical properties, too fast corrosion degradation rate and poor bone formation ability. The degradable magnesium-based composite materials prepared by combining the enhanced phase characteristics of magnesium and bioceramic particles are expected to take into account various properties and gradually become an active field in the research and industrial application of degradable medical metal materials.

[0003] Friction stir processing technology is a common technology for preparing metal-based composite materials and has been widely used to prepare various types of magnesium-based composite materials. In the process of preparing metal-based composite materials by friction stir processing, the stirring head needs to be pressed into the metal plate to be processed with a certain "downward pressure" to ensure that there are no defects such as holes inside the prepared composite material. At the same time, in order to ensure the refinement of the composite material and the homogenization of the internal ceramic particles, metal-based composite materials are usually prepared by multi-pass friction stir processing. It should be pointed out that in the multi-pass friction stir processing process, when the stirring head is pressed down each time, the stirring needle will penetrate into the unprocessed matrix metal, and there is an objective risk of introducing matrix metal inclusions into the composite material processed in the previous pass. In Chinese Patent ZL2018100354165 "A Controllable Degradable Magnesium-Based Functional Gradient Material and Preparation Method thereof" and Chinese Patent ZL2018104531934 "Preparation Method of Magnesium-Based Biocomposite Materials", the patentees both used multi-pass friction stir processing to prepare bioceramic-reinforced magnesium-based composite materials. Both patents use a single-specification stirring head to implement multiple-pass friction stir processing, so there is a risk of matrix metal inclusions in the magnesium-based composites prepared by the method. In fact, in the microstructure characterization of the WE43 / HA composite prepared by the applicant using a single-specification stirring head and multiple-pass friction stir processing, matrix metal inclusions in the form of banded structures were indeed found in the prepared composites, such as Figure 1a and Figure 1b shown.

[0004] The inclusion of matrix metal in magnesium-based composites will deteriorate the corrosion resistance and thermal stability of the composites, hindering their degradation performance and subsequent thermal processing potential. The corrosion potential of magnesium-based composites is different from that of matrix metals. The inclusion of matrix metals will form a corrosion galvanic pair with the composites and accelerate corrosion, resulting in undesirable non-uniform corrosion. When the WE43 / HA composites were immersed in simulated body fluids for 30 minutes, the corrosion morphology of the composites was observed using a laser confocal microscope. It was found that the inclusion of matrix metal (green) had undergone significant corrosion compared to the surrounding composites (yellow). The boundary between the corrosion morphologies of the two was very obvious, and even pitting pits (blue) appeared inside the inclusion of matrix metal. Figure 2 As shown. In addition, the thermal stability of the fine-grained matrix metal in the magnesium-based composite material is very poor. When heated at high temperature, the fine-grained matrix metal will coarsen rapidly, which directly deteriorates the thermal processing of the composite material and hinders the deep processing of composite materials. The WE43 / HA composite material was heat-treated at 400℃ for 30 minutes. From the microstructure, it can be found that the fine-grained matrix metal at room temperature has been drastically coarsened, while the grain size of the surrounding composite material has not changed significantly. The difference in the thermal stability of the two organizations is significant, as shown in Figure 2. Figure 3 As shown. At the same time, the location of the inclusion of matrix metal in magnesium-based composites is affected by the plastic flow behavior of the metal during the friction stir processing, and its distribution law is difficult to predict. The damage to the uniformity of the composite material performance is very obvious, which hinders the industrialization of magnesium-based composites. Therefore, it is necessary to develop a new method to eliminate the problem of matrix metal inclusions in medical degradable magnesium-based composites, which can also provide a technical solution for the regulation of the organization and performance of other particle-reinforced metal-based composites. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing biomedical magnesium-based composite materials without matrix metal inclusions in view of the deficiencies of the above-mentioned prior art. The method sequentially uses a large-sized stirring head and a small-sized stirring head to perform multiple reciprocating stir friction processing on the magnesium-based material to prepare the magnesium-based composite material, and the small-sized stirring head is used to effectively eliminate the newly introduced matrix metal when the large-sized stirring head is pressed down each time, and the ceramic particles are evenly distributed to avoid the occurrence of matrix metal inclusions, thereby improving the corrosion performance and thermal stability of the magnesium-based composite material, and solving the problem of the introduction of matrix metal inclusion defects that deteriorate its corrosion resistance and hot workability when preparing magnesium-based composite materials by existing stir friction processing.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a biomedical magnesium-based composite material without matrix metal inclusions, characterized in that the method comprises the following steps:

[0007] Step 1: sequentially perform grooving, powder filling and grooving sealing on the magnesium-based plate, and then use a large-size stirring head with a large shoulder size and a long stirring needle to perform multiple reciprocating stirring friction processing to form a processing area to obtain a magnesium-based composite material intermediate;

[0008] Step 2: In the processing area of ​​the magnesium-based composite intermediate in step 1, a small-sized stirring head with a small shoulder size and a short stirring needle is used to perform multiple reciprocating stir friction processing to obtain a biomedical magnesium-based composite material without matrix metal inclusions.

[0009] The above-mentioned method for preparing a biomedical magnesium-based composite material without matrix metal inclusions is characterized in that the component of the magnesium-based plate in step one is magnesium or a magnesium alloy; the grooving is performed on the surface of the magnesium-based plate using a four-edge flat-bottomed tungsten steel milling cutter, the four-edge flat-bottomed tungsten steel milling cutter is adapted to the width and depth of the groove formed by the grooving, and the two ends do not penetrate the magnesium-based plate.

[0010] The above-mentioned method for preparing a biomedical magnesium-based composite material without matrix metal inclusions is characterized in that the powder filling material in step 1 is nano hydroxyapatite powder.

[0011] The above-mentioned method for preparing a biomedical magnesium-based composite material without matrix metal inclusions is characterized in that the powder filling process in step 1 is: mixing nano-hydroxyapatite powder with anhydrous ethanol to form a paste and filling it into the tank body, smoothing the surface and then drying in the shade; the tank body sealing process is: using a curved needle-free stirring head to perform three passes of stir friction processing to seal the tank body, and the rotation speed is 300rpm~600rpm, the forward speed is 10mm / min~40mm / min, and there is no inclination. The powder filling process effectively reduces the porosity of the powder inside the tank body, so that it is not easy to produce defects such as holes during the subsequent stir friction processing.

[0012] The above-mentioned method for preparing a biomedical magnesium-based composite material without matrix metal inclusions is characterized in that the specifications of the large-size stirring head in step one are: shoulder diameter Φ15mm~25mm, needle length 6mm~12mm; the downward pressure of the multi-pass reciprocating stir friction processing is 0.4mm~0.8mm, the processing passes are 2~3 passes, the rotation speed is 300rpm~1500rpm, the forward speed is 30mm / min~100mm / min, and the inclination angle is 1°~2.5°.

[0013] The above-mentioned method for preparing a biomedical magnesium-based composite material without matrix metal inclusions is characterized in that the specifications of the small-sized stirring head in step 2 are: the shoulder diameter is 4 mm smaller than the shoulder diameter of the large-sized stirring head in step 1, and the needle length is 2 mm smaller than the needle length of the large-sized stirring head in step 1; the downward pressure of the multi-pass reciprocating stir friction processing is 0.1 mm to 0.3 mm, the processing passes are 2 to 3 times, the rotation speed is 300 rpm to 1500 rpm, the forward speed is 30 mm / min to 100 mm / min, and the inclination angle is 1° to 2.5°.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. Compared with the conventional method of preparing magnesium-based composite materials by multiple passes of single-size stirring heads, the present invention sequentially uses a large-size stirring head and a small-size stirring head to perform multiple passes of reciprocating stir friction processing on magnesium-based materials to prepare magnesium-based composite materials (such as Figure 4a As shown), in the processing area of ​​the magnesium-based composite intermediate prepared by the large-size stirring head ( Figure 4b The small size stirring head can effectively eliminate the newly introduced matrix metal ( Figure 4b The secondary stirring zone in the mixing process is created, and the ceramic particles are completely dispersed to avoid matrix metal inclusions, thereby eliminating the matrix metal inclusion defects in the composite material that would deteriorate its corrosion resistance and hot workability, improving the corrosion performance and thermal stability of the magnesium-based composite material, making it suitable for biomedical use.

[0016] 2. The present invention controls the specifications and downward pressure range of the small-sized stirring head, and further limits the multi-pass reciprocating stirring friction processing range of the small-sized stirring head to the processing area of ​​the magnesium-based composite material intermediate prepared by the large-sized stirring head, so as to effectively eliminate the irregular local matrix metal inclusions in the magnesium-based composite material, thereby improving the corrosion performance and thermal stability of the magnesium-based composite material.

[0017] 3. The ceramic granular hydroxyapatite powder filled in the biomedical magnesium-based composite material prepared by the method of the present invention is evenly distributed, has fine grains, and has uniform performance, eliminating the problem of matrix metal inclusions in local areas, which is beneficial to the deep processing and industrialization of medical magnesium-based composite materials.

[0018] 4. The preparation process of the present invention is simple and has significant effects, and it is expected to be promoted as a common method for regulating the microstructure and properties of other particle-reinforced metal-based composite materials.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1aThis is a characteristic diagram of matrix metal inclusions in the WE43 / HA composite material prepared by four-pass friction stir processing using a single-specification stirring head in the prior art.

[0021] Figure 1b This is a characteristic diagram of matrix metal inclusions in the WE43 / HA composite material prepared by six-pass friction stir processing using a single-specification stirring head in the prior art.

[0022] Figure 2 This is a surface corrosion morphology diagram of the WE43 / HA composite material containing matrix metal inclusions in the prior art after being immersed in simulated body fluid for 30 minutes.

[0023] Figure 3 This is a morphological diagram of abnormal growth of matrix metal grains in the WE43 / HA composite material in the prior art after being kept at 400°C for 30 minutes.

[0024] Figure 4a It is a schematic diagram of the sequential friction stir processing of large and small size stirring heads of the present invention.

[0025] Figure 4b This is a schematic diagram of the principle of sequential friction stir processing of large and small size stirring heads of the present invention.

[0026] Figure 5a This is a microstructure diagram of the transition area between the WE43 magnesium alloy matrix and the processing area in Example 1 of the present invention.

[0027] Figure 5b This is the microstructure diagram of the WE43 magnesium alloy matrix in Example 1 of the present invention.

[0028] Figure 5c This is a microstructure diagram of the processing area of ​​the large-sized stirring head in Example 1 of the present invention.

[0029] Figure 5d This is a microstructure diagram of the processing area of ​​the small-sized stirring head in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] Example 1

[0031] This embodiment includes the following steps:

[0032] Step 1: Use a four-edge flat-bottom tungsten steel milling cutter with a diameter of Φ2.0mm and a blade length of 6mm to groove the surface of a WE43 magnesium alloy plate with a size of 400mm×200mm×20mm in length×width×thickness. The four-edge flat-bottom tungsten steel milling cutter is adapted to the width and depth of the groove formed by the groove, and the two ends do not penetrate the WE43 magnesium alloy plate. Compressed air cooling is used during the groove opening process. Then, nano-hydroxyapatite powder (HA) with a particle size of 60nm is mixed with anhydrous ethanol to form a paste and filled into the groove. After smoothing the surface, it is dried in the shade. Then, a curved needle-free stirring head is used to perform three passes of stir friction processing to close the groove. The rotation speed is 300rpm, the forward speed is 20mm / min, and there is no inclination.

[0033] A large-size stirring head is used to perform three reciprocating friction stir processing to form a processing area, and a WE43 / HA magnesium-based composite material intermediate is obtained; the specifications of the large-size stirring head are: a shaft shoulder diameter of Φ18mm, a needle length of 8mm, a downward pressure of 0.5mm, a rotation speed of 800rpm, a forward speed of 50mm / min, and an inclination angle of 2.5° for the three reciprocating friction stir processing;

[0034] Step 2. In the processing area of ​​the WE43 / HA composite material intermediate in step 1, a small-sized stirring head is used to perform three reciprocating stir friction processing to obtain a biomedical WE43 / HA magnesium-based composite material without matrix metal inclusions; the specifications of the small-sized stirring head are: shoulder diameter Φ14mm, needle length 6mm; the downward pressure of the three reciprocating stir friction processing is 0.1mm, the rotation speed is 800rpm, the forward speed is 50mm / min, and the inclination angle is 2.5°.

[0035] Figure 5a is the microstructure diagram of the transition area between the WE43 magnesium alloy matrix and the processing area in this embodiment, Figure 5b is the microstructure diagram of the WE43 magnesium alloy plate in this embodiment, Figure 5c This is the microstructure diagram of the processing area of ​​the large-size stirring head in this embodiment. Figure 5d This is the microstructure diagram of the processing area of ​​the small-sized stirring head in this embodiment. Figure 5a to Figure 5d It can be seen that compared with the processing area of ​​the large-size stirring head, i.e., the 8mm stirring head, the hydroxyapatite (HA) powder particles in the composite material microstructure in the processing area of ​​the small-size stirring head, i.e., the 6mm stirring head, are finer and more evenly dispersed, and completely fall into the 8mm stirring head processing area.

[0036] Multiple groups of metallographic specimens were prepared from the biomedical WE43 / HA magnesium-based composite material prepared in this embodiment by wire cutting. No matrix metal inclusions were observed in the microstructures of each group of metallographic specimens, and the microstructures were uniform everywhere.

[0037] Further, it can be seen from the simulated body fluid immersion experiment that the corrosion mechanism of the biomedical WE43 / HA magnesium-based composite material prepared in this embodiment is mainly uniform corrosion.

[0038] The biomedical WE43 / HA magnesium-based composite material prepared in this example was subjected to a heat preservation treatment at 400° C. for 30 minutes to prepare multiple groups of metallographic specimens. Observation showed that there was no abnormal coarsening of grains in the microstructure of each group of metallographic specimens.

[0039] Example 2

[0040] This embodiment includes the following steps:

[0041] Step 1: Use a four-edge flat-bottom tungsten steel milling cutter with a diameter of Φ2.0mm and a blade length of 6mm to groove the surface of a WE43 magnesium alloy plate with a size of 400mm×200mm×20mm in length×width×thickness. The four-edge flat-bottom tungsten steel milling cutter is adapted to the width and depth of the groove formed by the groove, and the two ends do not penetrate the WE43 magnesium alloy plate. Compressed air cooling is used during the groove opening process. Then, nano-hydroxyapatite powder (HA) with a particle size of 60nm is mixed with anhydrous ethanol to form a paste and filled into the groove. After smoothing the surface, it is dried in the shade. Then, a curved needle-free stirring head is used to perform three passes of stir friction processing to close the groove. The rotation speed is 600rpm, the forward speed is 40mm / min, and there is no inclination.

[0042] A large-size stirring head is used to perform two reciprocating friction stir processing to form a processing area, and a WE43 / HA magnesium-based composite material intermediate is obtained; the specifications of the large-size stirring head are: a shaft shoulder diameter of Φ25mm, a needle length of 12mm, a downward pressure of 0.8mm, a rotation speed of 300rpm, a forward speed of 30mm / min, and an inclination angle of 1° in the two reciprocating friction stir processing;

[0043] Step 2. In the processing area of ​​the WE43 / HA magnesium-based composite material intermediate in step 1, a small-sized stirring head is used to perform two reciprocating stir friction processes to obtain a biomedical WE43 / HA magnesium-based composite material without matrix metal inclusions; the specifications of the small-sized stirring head are: shoulder diameter Φ21mm, needle length 10mm; the downward pressure of the three reciprocating stir friction processes is 0.3mm, the rotation speed is 300rpm, the forward speed is 30mm / min, and the inclination angle is 1°.

[0044] Multiple groups of metallographic specimens were prepared from the biomedical WE43 / HA magnesium-based composite material prepared in this embodiment by wire cutting. No matrix metal inclusions were observed in the microstructures of each group of metallographic specimens, and the microstructures were uniform everywhere.

[0045] Example 3

[0046] This embodiment includes the following steps:

[0047] Step 1: Use a four-edged flat-bottomed tungsten steel milling cutter with a diameter of Φ2.0mm and a blade length of 6mm to groove the surface of a magnesium plate with a size of 400mm×200mm×20mm in length×width×thickness. The four-edged flat-bottomed tungsten steel milling cutter is adapted to the width and depth of the groove formed by the groove, and the two ends do not penetrate the magnesium plate. Compressed air is used for cooling during the groove. Then, nano-hydroxyapatite powder (HA) with a particle size of 60nm is mixed with anhydrous ethanol to form a paste and filled into the groove. After smoothing the surface, it is dried in the shade. Then, a curved needle-free stirring head is used to stir and friction process the closed groove for 3 times, and the rotation speed is 400rpm, the forward speed is 10mm / min, and there is no inclination.

[0048] A large-size stirring head is used to perform two reciprocating friction stir processing to form a processing area to obtain a Mg / HA magnesium-based composite material intermediate; the specifications of the large-size stirring head are: a shaft shoulder diameter of Φ15mm, a needle length of 6mm, a downward pressure of 0.4mm, a rotation speed of 1500rpm, a forward speed of 100mm / min, and an inclination angle of 2.0° for the two reciprocating friction stir processing;

[0049] Step 2. In the processing area of ​​the Mg / HA magnesium-based composite material intermediate in step 1, a small-sized stirring head is used to perform three reciprocating stir friction processing to obtain a biomedical Mg / HA magnesium-based composite material without matrix metal inclusions; the specifications of the small-sized stirring head are: shoulder diameter Φ11mm, needle length 4mm; the downward pressure of the three reciprocating stir friction processing is 0.2mm, the rotation speed is 1500rpm, the forward speed is 100mm / min, and the inclination angle is 2.0°.

[0050] Multiple groups of metallographic specimens were prepared from the biomedical Mg / HA magnesium-based composite material prepared in this embodiment by wire cutting. No matrix metal inclusions were observed in the microstructures of each group of metallographic specimens, and the microstructures were uniform everywhere.

[0051] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a biomedical magnesium-based composite material without matrix metal inclusions, characterized in that: The method comprises the following steps: Step 1, sequentially perform grooving, powder filling and groove sealing treatments on the magnesium-based plate, and then use a large-size stirring head with a large shoulder size and a long stirring needle to perform multiple reciprocating stir friction processing to form a processing area to obtain a magnesium-based composite material intermediate; the powder filled with powder is nano-hydroxyapatite powder; the specifications of the large-size stirring head are: shoulder diameter Φ15mm~25mm, needle length 6mm~12mm; the downward pressure of the multiple reciprocating stir friction processing is 0.4mm~0.8mm, the processing passes are 2~3 passes, the rotation speed is 300rpm~1500rpm, the forward speed is 30mm / min~100mm / min, and the inclination angle is 1°~2.5°; Step 2. In the processing area of ​​the magnesium-based composite material intermediate in step 1, a small-sized stirring head with a small shoulder size and a short stirring needle is used to perform multiple reciprocating stir friction processing to obtain a biomedical magnesium-based composite material without matrix metal inclusions; the specifications of the small-sized stirring head are: the shoulder diameter is 4 mm smaller than the shoulder diameter of the large-sized stirring head in step 1, and the needle length is 2 mm smaller than the needle length of the large-sized stirring head in step 1; the downward pressure of the multiple reciprocating stir friction processing is 0.1 mm to 0.3 mm, the processing passes are 2 to 3 times, the rotation speed is 300 rpm to 1500 rpm, the forward speed is 30 mm / min to 100 mm / min, and the inclination angle is 1° to 2.5°.

2. The method for preparing a biomedical magnesium-based composite material without matrix metal inclusions according to claim 1, characterized in that: The magnesium-based plate in step 1 is made of magnesium or magnesium alloy; the grooving is performed on the surface of the magnesium-based plate using a four-edged flat-bottom tungsten steel milling cutter, the four-edged flat-bottom tungsten steel milling cutter is adapted to the width and depth of the groove formed by the grooving, and the two ends do not penetrate the magnesium-based plate.

3. The method for preparing a biomedical magnesium-based composite material without matrix metal inclusions according to claim 1, characterized in that: The powder filling process in step one is: mixing nano-hydroxyapatite powder with anhydrous ethanol to form a paste and filling it into the tank body, smoothing the surface and drying it in the shade; the tank body sealing process is: using a curved needle-free stirring head to perform three passes of stirring friction processing to seal the tank body, and the rotation speed is 300rpm~600rpm, the forward speed is 10mm / min~40mm / min, and there is no inclination angle.

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