CN112077307A - A kind of preparation method of 3D printing doped graphene high-strength titanium alloy parts - Google Patents

Abstract

The invention discloses a preparation method for 3D printing graphene-doped high-strength titanium alloy parts. First, pure titanium powder is modified; the modified pure titanium powder is mixed with spherical pure titanium powder; the mixed powder is mixed with The flat graphene powder is mixed, and the obtained mixed powder adopts the laser selective melting technology to prepare the deposited state parts; the invention changes the performance of the parts from the raw materials, and prepares the titanium alloy parts by the laser selective melting method, and its hardness and strength are obviously higher than Undoped graphene parts.

Description

A kind of preparation method of 3D printing doped graphene high-strength titanium alloy parts

technical field

The invention belongs to the technical field of 3D printing, and in particular relates to a preparation method for 3D printing high-strength titanium alloy parts doped with graphene.

Background technique

Titanium alloy is a metal material with excellent corrosion resistance. In addition, titanium alloys have the advantages of low density, higher specific strength than ordinary metals, good biocompatibility, and excellent high temperature strength, so they are used as aerospace materials, chemical materials, automotive materials, biological materials, marine engineering. Materials, building materials, etc. are widely used in various fields. The composite material with titanium alloy as the matrix is to add appropriate reinforcement phase on the basis of the titanium alloy matrix. The titanium matrix composite material combines the high strength and high modulus of the reinforcement phase and the ductility and toughness of the titanium alloy matrix. Compared with titanium matrix, it has higher compressive or tensile strength and obtains more stable high temperature performance. After the research and practice of scholars, it has been found that the titanium-based composite material generated by titanium and graphene does have mechanical properties and better physical and chemical properties than the titanium alloy matrix as expected, and the strength and corrosion resistance of titanium-graphene composite material. The properties such as wear resistance and oxidation resistance are improved with the addition of the reinforcement. The formed reinforcement TiC is the key to the improvement of the performance of the titanium-graphene composite material. TiC can improve the strength and resistance of the metal matrix through dispersion strengthening. Wear, high temperature and corrosion resistance properties. Therefore, titanium-graphene composites play an increasingly important role in aerospace, biomedical and other fields, and have received a lot of attention from researchers.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method for 3D printing graphene-doped high-strength titanium alloy parts, which solves the problem that the cost of raw materials required for traditional 3D-prepared titanium alloy parts is too high and the strength gradually fails to meet the requirements of use. question.

The technical solution adopted in the present invention is, a preparation method of 3D printing doped graphene high-strength titanium alloy parts, which is specifically implemented according to the following steps:

Step 1, modifying the pure titanium powder;

Step 2, mixing the pure titanium powder modified in step 1 with spherical pure titanium powder;

Step 3, mixing the mixed powder obtained in step 2 with the flat graphene powder to obtain a mixed powder;

In step 4, the mixed powder obtained in step 3 is used for laser selective melting technology to prepare deposited parts.

The feature of the present invention also lies in:

Wherein the modification process of step 1 is specifically:

The pure titanium powder was modified by a high-speed ball milling process: the pure titanium powder was ball-milled by a high-speed vibrating ball mill with a speed of 1200 r/min, and the ball-to-material ratio was 5:1. Ball milling time 15min;

Wherein the pure titanium powder in step 1 is a special-shaped pure titanium powder prepared by hydrogenation and dehydrogenation;

Before mixing in step 2, the pure titanium powder modified in step 1 is screened, and the particle size of the pure titanium powder is not greater than 53 μm. Mixing in an omnidirectional planetary ball mill, the mixing ratio of the spherical pure titanium powder and the modified pure titanium powder is 8:2 or 7:3;

Among them, the rotational speed of the QF-WL-4L omnidirectional planetary ball mill is 300r/min, and the ball milling time is 3h;

The average particle size of spherical pure titanium powder is 45μm～150μm;

Wherein, in step 2, after mixing by the omnidirectional planetary ball mill, the mixed powder is put into a drying oven for drying for 1-1.5 hours, and the temperature of the drying oven is 70°C;

Wherein, in step 3, the mixed powder obtained in step 2 is mixed with graphene powder in a QF-WL-4L omnidirectional planetary ball mill, and the ratio of mixed powder to graphene powder is 99:1, and the average particle size of graphene powder is 99:1. is 3075μm;

The ball milling tank adopts a vacuum ball milling tank. During the ball milling process, 1.5% of the dispersant alcohol is added to the powder volume. The abrasive is stainless steel grinding beads. The ball-to-material ratio is 5:1. The powder was dried in a drying oven at 70°C for 2h;

Among them, the process parameters of the laser selective melting technology in step 4 are: the size of the laser beam spot is 45μm ~ 50μm, the laser power is 80w ~ 100w, the scanning speed is 500mm·s ^-1 ~ 650mm·s ^-1 , and the laser scanning method is checkerboard. , the preheating temperature is 200℃, and the thickness of each layer is 25μm;

Wherein, in step 4, before the laser selective melting technology works, argon gas is injected into the laser selective melting equipment until the oxygen content of the air in the equipment is less than 0.2%.

The beneficial effects of the present invention are:

The present invention proposes a preparation method for low-cost high-strength titanium alloy parts doped with graphene by 3D printing. The properties of the parts are changed from raw materials, and the titanium alloy parts are prepared by the method of laser selective melting. The hardness and strength are obviously higher than those of titanium alloy parts. Undoped graphene parts.

Description of drawings

Figures 1(a)-(c) are respectively the pure titanium powder generated by hydrogenation and dehydrogenation in a method for preparing a 3D printing graphene-doped high-strength titanium alloy part of the present invention before modification and the doped particles with different particle sizes. SEM image of spherical titanium powder;

Figures 2(a)-(e) are respectively the morphological diagrams of high-energy ball milling special-shaped powder at different times in a preparation method for 3D printing graphene-doped high-strength titanium alloy parts according to the present invention;

3 is a SEM image of the mixed titanium powder in step 2 in a method for preparing a 3D printing graphene-doped high-strength titanium alloy part of the present invention;

Fig. 4(a) and Fig. 4(b) are respectively powders formed by mixing titanium powder and graphene powder in a ratio of 99:1 in a method for preparing 3D printing graphene-doped high-strength titanium alloy parts of the present invention SEM image and energy spectrum;

5 is a diagram of a formed part with different powder ratios in a preparation method of a 3D printing graphene-doped high-strength titanium alloy part of the present invention;

6 is a compressive stress-strain curve diagram of different powder ratios in a preparation method of a 3D printing graphene-doped high-strength titanium alloy part of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention provides a preparation method for 3D printing low-cost high-strength titanium alloy parts doped with graphene, which is specifically implemented according to the following steps:

Step 1, using a high-speed ball milling process to modify the special-shaped pure titanium powder (as shown in Figure 1(b)) prepared by the hydrogenation dehydrogenation method: the high-speed ball milling process specifically includes using a high-speed vibration ball mill with a rotation speed of 1200r/min. The pure titanium powder prepared by dehydrogenation was ball-milled, the ratio of ball to material was 5:1, the material of the tank and the ball were stainless steel, 1.5% stearic acid was added in the ball milling process, and the ball milling time was selected from 0min, 15min, 30min, 45min and 60min as a comparison, the SEM morphology of the modified powder is shown in Figure 2(a) ~ Figure 2(e), it is found that the sharp edges and corners of the pure titanium powder are passivated when the ball milling time is 15min and 30min, and the morphology is nearly spherical, more than After 30 minutes, the pure titanium powder will be severely refined, and there will be serious agglomeration. The pure titanium powder with a ball milling time of 30 minutes also has a slight agglomeration phenomenon, so the performance of the pure titanium powder with a ball milling time of 15 minutes is further characterized: the pure titanium powder with a ball milling time of 15 minutes is further characterized: The maximum particle size of the powder is 45.2μm, the minimum particle size is 12.1μm, the average particle size is 23.2μm, the angle of repose before ball milling is 38.7°, and the angle of repose of the modified pure titanium powder is 34.3°. It can meet the requirements of powder fluidity and reduce the cost of raw materials. It further shows that pure titanium powder modification uses high speed and high energy input, which can achieve pure titanium powder crushing and sharp corner passivation, and improve the fluidity of modified powder. However, the ball milling time should be strictly controlled. The longer the time, the higher the temperature in the ball milling tank, and the decomposition temperature of stearic acid is above 63 °C. The qualitative control of the phase of pure titanium powder can be realized by controlling the amount of stearic acid added. ;

Among them, the process of high-speed ball milling can make irregular powders undergo morphology modification and phase modification at the same time. The modification of morphology is mainly reflected in the passivation of edges and corners of irregular powders, partial fragmentation, and reduction of particle size distribution. Appearance and morphology are nearly spherical; phase modification is to use frictional heat generated during ball milling to generate high temperature, so that excessive stearic acid is decomposed and pure titanium powder is in situ to form non-stoichiometric titanium hydride and titanium carbide. A diffuse second phase is formed in the

Among them, stearic acid is a low-cost 18-carbon chain saturated fatty acid, and its decomposition temperature is 63 ° C, so excess stearic acid will be decomposed into carbon, hydrogen and other elements in the process of high-energy ball milling, which is the phase modification of powder. provide elements;

Step 2: Mix the pure titanium powder modified in Step 1 with spherical pure titanium powder with an average particle size of 75 μm (as shown in Figure 1(a)) to obtain mixed powder: The pure titanium powder is sieved, and the particle size of the pure titanium powder after screening is not greater than 53 μm, and then the modified pure titanium powder and spherical pure titanium powder are mixed in an omnidirectional planetary ball mill, as shown in Figure 3; The D50 of pure titanium powder is 100 μm, which is different from the previous laser selective melting using spherical powder with an average particle size of 15 μm to 53 μm (as shown in Figure 1(c)), and the voids between spherical powders with larger particle sizes increase. , the mixing ratio of spherical pure titanium powder and modified titanium powder is 8:2 or 7:3, the rotational speed of the omnidirectional planetary ball mill is 300r/min, and the mixing time is 3h. After mixing, put the mixed powder into the drying box. Drying for 1h in the drying oven temperature is 70 ℃, drying is mainly to remove the moisture adsorbed by the mixed powder;

Step 3, the mixed powder obtained in step 2 and the graphene nanopowder with an average particle size of 3075 μm are mixed in a ratio of 99:1, a vacuum ball mill is used to prevent oxidation of the titanium powder in the ball-ink ball milling process, and the dispersant is alcohol (consumption). is 1.5% of the volume of the powder), the abrasive is stainless steel grinding beads, the ball-to-material ratio is 5:1, the rotational speed is 300r/min, and the ball milling time is 3h to obtain a graphene-titanium composite powder with a graphene mass fraction of 1%. The mixed powder was dried at 70°C for two hours for use (the mixed powder is shown in the topography of Figure 4(a) and the energy spectrum at a certain point in Figure 4(b));

In step 4, the titanium powder and graphene mixed powder obtained in step 3 are prepared by laser selective melting technology to prepare the deposited parts (as shown in Figure 5): Concept Laser MLAB cusing R-type laser metal additive manufacturing process produced by CONCEPT Company The system prints the mixed powder. First, it uses Solidworks software, Pro/Engineer software or Unigraphic software to build a 3D solid model, and then uses Magics software to slice the 3D solid model to obtain layered information at different heights; The treated mixed powder is flushed into argon in the glove box of the laser additive manufacturing machine. After the oxygen content of the air in the printing chamber is reduced to below 0.2%, the mixed powder is loaded into the silo, and then the powder is spread evenly by the roller. Lay powder, the thickness of each layer of powder is 25μm. After each layer of powder is laid, the scanning system starts to print according to the obtained layering information under the control of the computer. process until the completion of the three-dimensional parts manufacturing, in which the process parameters of the laser selective melting technology are: the laser beam spot size is 45μm ~ 50μm, the laser power is 80w ~ 100w, the scanning speed is 500mm·s ^-1 ~ 650mm·s ^-1 , pre- The heat temperature was 200°C.

The advantages of a preparation method for 3D printing graphene-doped low-cost high-strength titanium alloy parts of the present invention are explained from the raw material preparation and forming process: the traditional 3D printing powder has high raw material cost, and the low-cost hydrogenation dehydrogenation titanium powder is mixed with After the stearic acid is mixed, high-energy ball milling is performed to improve the fluidity of the powder, and the decomposition of stearic acid is used to provide solid solution elements such as carbon and hydrogen, and the non-stoichiometric titanium hydride and titanium carbide are formed in situ with the pure titanium powder. The modified powder is mixed with spherical powder by ball milling to improve the fluidity and bulk density of the printing raw material, and the addition of graphene powder increases the compressive strength and yield strength of the printed parts at room temperature and high temperature at the same time. The invention proposes to form high-performance titanium alloy parts by laser selective melting technology, which utilizes the solid solution strengthening of interstitial elements and titanium and the TiC dispersion strengthening generated by the reaction of graphene and pure titanium to improve the strength and hardness of the formed parts, and the strength and hardness of the formed parts are significantly higher. in traditional preparation methods.

Example 1

Step 1, put the pure titanium powder of hydrogenation dehydrogenation into a high-speed vibrating ball mill with a rotating speed of 1200r/min and carry out ball milling with a ball milling time of 15min, and the addition of stearic acid is 1.5%;

Step 2: Mix the spherical pure titanium powder with a particle size distribution of 325 meshes to 100 meshes (45 μm to 150 μm) and the modified pure titanium powder in a ratio of 8:2, on an omnidirectional planetary ball mill at a rate of 300 r/min The rotating speed is run for 1h to mix evenly, and finally it is dried in a drying oven at 70℃ for 1h;

In step 3, the mixed powder obtained in step 2 and the graphene powder are mixed in a QF-WL-4L omnidirectional planetary ball mill, and the ratio of the mixed powder to the graphene powder is 99:1, and the average particle size of the graphene powder is 3075μm;

The ball milling tank adopts a vacuum ball milling tank. During the ball milling process, 1.5% of the dispersant alcohol is added to the powder volume. The abrasive is stainless steel grinding beads. The ball-to-material ratio is 5:1. The powder was dried in a drying oven at 70°C for 2h;

Step 4: Control the laser energy density by changing the forming process parameters, use the Pro/Engineer layering software to slice and discretize the three-dimensional solid model in step 1, use the Magics software layering, the scanning path is zigzag mesh scanning, and The acceptance rate is 50%, and the cross-sectional data of each layer is obtained, and then the cross-sectional data of each layer is imported into the laser selective melting and forming equipment as a laser scanning path, and then the processing parameters are set on the laser selective melting equipment. The processing parameters include the metal powder layer. Thickness, beam spot diameter, overlap ratio, laser power, scanning speed; metal powder layer thickness is 25μm; beam spot diameter is 45μm; the laser power is 100w; the laser scanning speed is 600mm/s, and the substrate preheating temperature is 200 °C;

The treated mixed powder is flushed into argon in the glove box of the laser additive manufacturing machine. After the oxygen content of the air in the printing chamber is reduced to below 0.2%, the mixed powder is spread on the bottom plate, and then a larger The laser spot and high scanning speed are used to preheat the mixed powder on the bottom plate; the preheated mixed powder is melted and scanned selectively by the laser according to the laser scanning path to form a single-layer solid sheet; the lifting platform descends One layer, repeat the process of laying the mixed powder and preheating and the process of selectively melting and scanning the preheated mixed powder to form a single-layer solid sheet, until the preparation of each layer is completed, and the laser is obtained. Selective melting of the molded part; finally, use compressed air to remove excess powder in the molded part, clean it and then dry it to obtain dense parts, as shown in Figure 5, it can be seen that the appearance of the molded part is silvery white with metallic luster, without Over-burning or poor fusion phenomenon, and the forming accuracy is 0.3 ~ 0.5mm;

Example 2

Step 1, modify the pure titanium powder:

The special-shaped pure titanium powder prepared by hydrodehydrogenation was modified by high-speed ball milling process: the pure titanium powder was ball-milled by a high-speed vibrating ball mill with a speed of 1200 r/min, and the ball-to-material ratio was 5:1. 1.5% stearic acid, ball milling time 15min;

Step 2, mixing the pure titanium powder modified in step 1 with spherical pure titanium powder:

The modified pure titanium powder and spherical pure titanium powder were mixed in a QF-WL-4L omnidirectional planetary ball mill, the rotation speed was 300r/min, and the ball milling time was 3h. The mixing ratio of pure titanium powder is 8:2, and the average particle size of spherical titanium powder is 75 μm. After mixing by omnidirectional planetary ball mill, the mixed powder is placed in a drying oven for drying for 1.5h, and the drying oven temperature is 70 ℃;

In step 3, the mixed powder obtained in step 2 and the graphene powder are mixed in a QF-WL-4L omnidirectional planetary ball mill, and the ratio of the mixed powder to the graphene powder is 99:1, and the average particle size of the graphene powder is 3075μm;

The ball milling tank adopts a vacuum ball milling tank. During the ball milling process, 1.5% of the dispersant alcohol is added to the powder volume. The abrasive is stainless steel grinding beads. The ball-to-material ratio is 5:1. The powder was dried in a drying oven at 70°C for 2h;

In step 4, the mixed powder obtained in step 3 is used to prepare the deposited parts by laser selective melting technology. The process parameters of the optical selective melting technology are: the size of the laser beam spot is 50 μm, the laser power is 80 w, and the scanning speed is 650 mm·s ^{− 1.} The laser scanning method is checkerboard type, the preheating temperature is 200°C, and the thickness of each layer of powder is 25μm. Before the optical selective melting technology works, argon is injected into the laser selective melting equipment until the oxygen content of the air in the equipment is less than 0.2%.

Example 3

Step 1, modify the pure titanium powder:

The special-shaped pure titanium powder prepared by hydrodehydrogenation was modified by high-speed ball milling process: the pure titanium powder was ball-milled by a high-speed vibrating ball mill with a speed of 1200 r/min, and the ball-to-material ratio was 5:1. 1.5% stearic acid, ball milling time 15min;

Step 2, mixing the pure titanium powder modified in step 1 with spherical pure titanium powder:

The modified pure titanium powder and spherical pure titanium powder were mixed in a QF-WL-4L omnidirectional planetary ball mill, the rotation speed was 300r/min, and the ball milling time was 3h. The mixing ratio of the pure titanium powder is 7:3, and the average particle size of the spherical titanium powder is 75 μm. After mixing by the omnidirectional planetary ball mill, the mixed powder is put into a drying oven for drying for 2 hours, and the drying oven temperature is 70 ℃;

In step 3, the mixed powder obtained in step 2 and the graphene powder are mixed in a QF-WL-4L omnidirectional planetary ball mill, and the ratio of the mixed powder to the graphene powder is 99:1, and the average particle size of the graphene powder is 3075μm;

The ball milling tank adopts a vacuum ball milling tank. During the ball milling process, 1.5% of the dispersant alcohol is added to the powder volume. The abrasive is stainless steel grinding beads. The ball-to-material ratio is 5:1. The powder was dried in a drying oven at 70°C for 2h;

In step 4, the mixed powder obtained in step 3 is used to prepare the deposited parts by the laser selective melting technology. The process parameters of the optical selective melting technology are: the laser beam spot size is 45 μm, the laser power is 90 w, and the scanning speed is 600 mm·s ^{− 1.} The laser scanning method is checkerboard type, the preheating temperature is 200°C, and the thickness of each layer of powder is 25μm. Before the optical selective melting technology works, argon is injected into the laser selective melting equipment until the oxygen content of the air in the equipment is less than 0.2%.

After testing, it can be seen that the highest density of the titanium alloy prepared in the embodiment of the present invention is 98.32%, and the compressive stress-strain curves of the formed parts with different ratios of raw materials are shown in Figure 6, and it can be seen that the powder mixing ratio is 8:2 (the line The maximum compressive strength at a) is 1580MPa, the compressive strength at the mixing ratio of 7:3 (line b) is 1040MPa, and the strength and plasticity of the mixing ratio of 8:2 are better than those of the mixing ratio of 7:2: 3 The plasticity of the sample, the strength and plasticity of the 8:2 ratio forming part are improved due to the effect obtained by the dispersion distribution of the second phase in the titanium matrix.

Claims (10)

1. a kind of preparation method of 3D printing doped graphene high-strength titanium alloy parts, is characterized in that, is specifically implemented according to the following steps: Step 1, modifying the pure titanium powder; Step 2, mixing the pure titanium powder modified in step 1 with spherical pure titanium powder; Step 3, mixing the mixed powder obtained in step 2 with the flat graphene powder to obtain a mixed powder; In step 4, the mixed powder obtained in step 3 is used for laser selective melting technology to prepare deposited parts. 2. the preparation method of a kind of 3D printing doped graphene high-strength titanium alloy parts according to claim 1, is characterized in that, the modification process of described step 1 is specifically: The pure titanium powder was modified by a high-speed ball milling process: the pure titanium powder was ball-milled by a high-speed vibrating ball mill with a speed of 1200 r/min, and the ball-to-material ratio was 5:1. Ball milling time 15min. 3 . The method for preparing a 3D printing graphene-doped high-strength titanium alloy part according to claim 1 , wherein the pure titanium powder in the step 1 is a special-shaped pure titanium powder prepared by hydrogenation and dehydrogenation. 4 . 4. The preparation method of a kind of 3D printing graphene-doped high-strength titanium alloy parts according to claim 1, characterized in that, in the step 2, before mixing, the pure titanium powder after the modification treatment in step 1 is processed. Screening, the particle size of pure titanium powder is not more than 53μm, and then the screened pure titanium powder and spherical pure titanium powder are mixed in a QF-WL-4L omnidirectional planetary ball mill. The spherical pure titanium powder and modified treatment The mixing ratio of the final pure titanium powder is 8:2 or 7:3. 5. the preparation method of a kind of 3D printing doped graphene high-strength titanium alloy parts according to claim 4, is characterized in that, the rotational speed of described QF-WL-4L type omnidirectional planetary ball mill is 300r/min, Ball milling time 3h. 6 . The method for preparing 3D printing graphene-doped high-strength titanium alloy parts according to claim 4 , wherein the spherical pure titanium powder has an average particle size of 45 μm to 150 μm. 7 . 7. the preparation method of a kind of 3D printing doped graphene high-strength titanium alloy parts according to claim 4, is characterized in that, in the described step 2, after the omnidirectional planetary ball mill is mixed, the mixed powder is put into a drying box Dry for 1-1.5h in the drying oven at 70°C. 8. the preparation method of a kind of 3D printing doped graphene high-strength titanium alloy parts according to claim 1, is characterized in that, in described step 3, the mixed powder obtained through step 2 and graphene powder are mixed in QF -WL-4L omnidirectional planetary ball mill for ball milling and mixing, the ratio of mixed powder and graphene powder is 99:1, and the average particle size of graphene powder is 3075μm; The ball milling tank adopts a vacuum ball milling tank. During the ball milling process, 1.5% of the dispersant alcohol is added to the powder volume. The abrasive is stainless steel grinding beads. The ball-to-material ratio is 5:1. The powder was dried in a drying oven at 70°C for 2h. 9. The preparation method of a 3D printing graphene-doped high-strength titanium alloy parts according to claim 1, wherein the process parameters of the laser selective melting technology in the step 4 are: the laser beam spot size is 45 μm ~50μm, laser power is 80w ~ 100w, scanning speed is 500mm·s ^-1 ~ 650mm·s ^-1 , laser scanning method is checkerboard type, preheating temperature is 200℃, and the thickness of each layer is 25μm. 10 . The method for preparing a 3D printing graphene-doped high-strength titanium alloy part according to claim 1 , wherein in the step 4, the laser selective melting equipment is charged with argon gas before the laser selective melting technology works. 11 . To the equipment air oxygen content is less than 0.2%.

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