CN107096924A - The preparation method and product of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing - Google Patents

Abstract

The invention discloses a method for preparing a spherical metal-based rare earth nanocomposite powder that can be used for three-dimensional printing. (1) adding light metal raw materials into a crucible of an induction furnace, adjusting and controlling induction current heating to melt the light metal raw materials into a liquid melt; (2) ) controlling the temperature of the light metal melt to be within the range of 50-100°C higher than its melting point, adding 0-20.0wt% nanomaterials to the metal melt and ensuring uniform dispersion to form a mixed melt; (3) to the formed in step (2) Add 0‑1.0wt% rare earth materials into the mixed melt and ensure uniform dispersion; (4) Make up for the burnt elements to adjust the chemical composition of the alloy (5) Turn on high-purity argon, and concentrate it from one airflow to the mist The atomizing nozzle maintains the atomizing air pressure and power, and the evenly mixed composite material melt flows out from the infusion tube, falls freely for a certain distance, and is broken into small spherical droplets under the action of high-pressure gas, and quickly condenses into spherical powder particles. Products prepared by this method can be more effectively applied to three-dimensional printing technology.

Description

Preparation of a spherical metal-based rare earth nanocomposite powder for 3D printing Methods and Products

technical field

The invention belongs to the field of new materials, and in particular relates to a preparation method and product of a spherical metal-based rare earth nanocomposite powder that can be used for three-dimensional printing.

Background technique

In recent years, in the development of metal matrix composite materials, the development of light metal (aluminum, lithium, magnesium, titanium and other pure metals and their alloys) matrix composite materials is particularly rapid. Nanomaterials have a special microstructure of ultra-fine grains and a large number of internal interfaces, so they have many special mechanical and physical and chemical properties. Adding nanomaterials can effectively improve the tensile strength, hardness, wear resistance, etc. of light metal matrix composites, and can Change the physical properties of light metals such as electrical conductivity, thermal conductivity, and thermal expansion coefficient. Therefore, the preparation of nanomaterials light metal matrix composites has become a research hotspot. At present, the preparation methods of light metal matrix composites only need powder metallurgy, spark plasma sintering, stirred casting, pressure infiltration, spray deposition and so on. However, these methods are difficult to prepare light metal matrix composites with complex structures, thus restricting the application and development of light metal matrix composites.

With the rise of 3D printing technology, researchers at home and abroad have begun to combine nanomaterial-reinforced light metal matrix composites with 3D printing technology (mainly including laser selective melting SLM, electron beam selective melting EBM, laser near net shaping LENS, etc.), The advantages of nanomaterials that can significantly improve the mechanical properties of light metal matrix and the characteristics of 3D printing that can manufacture complex structural parts are realized to realize the rapid prototyping of complex structural parts of light metal matrix nanocomposites. At present, the commonly used nano-reinforcement materials for light metals include nano-ceramic particles (Al ₂ O ₃ , TiC, TiB, SiC, SiO ₂ , B ₄ C, diamond), nano-carbon materials (carbon fibers, carbon nanotubes, graphene, etc.), mainly through The method of high-energy ball milling is mixed with light metal powder, and then rapid melting is realized by powder spreading or optical internal powder feeding. This method has the following disadvantages: (1) The agglomeration of nanomaterials occurs due to strong van der Waals force and large surface tension, and the density difference between nanomaterials and light metals is large. It is difficult to disperse uniformly in light metal powder, so that stress concentration points are formed in the 3D printed parts of light metal matrix nanocomposites, resulting in cracks and brittleness. (2) The light metal powder with strong ductility is prone to extrusion deformation under the action of the grinding ball, the shape changes from spherical to flake or spherical, the fluidity of the powder decreases, and the compaction density decreases. (3) The wettability between the nanomaterials and the light metal matrix phase is very poor, and at the same time, the difference in thermal expansion coefficient between them is large, resulting in that the liquid phase formed during the forming process cannot be spread uniformly, and the subsequent solidification process Cracks appear due to large shrinkage stress. (4) The heat accumulation effect of the ball milling process can easily lead to a sharp increase in the oxygen content of the light metal powder, and the ball milling process needs to be carried out in a vacuum or a protective atmosphere, which increases the manufacturing cost.

Contents of the invention

In order to avoid the disadvantages of using ball milling in the prior art to prepare powders that can be used for three-dimensional printing, the purpose of the present invention is to provide a preparation method and product of spherical metal-based rare earth nanocomposite powders that can be used for three-dimensional printing. The product can be more effectively applied to 3D printing technology.

To achieve the above object, the present invention provides the following technical solutions:

1. A method for preparing a spherical metal-based rare earth nanocomposite powder that can be used for three-dimensional printing, comprising the steps of:

(1) Add the light metal raw material into the crucible of the induction furnace, evacuate the crucible and fill it with argon, adjust the induction current heating to melt the light metal raw material into a liquid melt;

(2) Control the temperature of the light metal melt to be 50-100°C higher than its melting point, add 0-20.0wt% nanomaterials to the metal melt and ensure uniform dispersion to form a mixed melt, and adjust the induced current intensity to 5-100°C 25A;

(3) Add 0-1.0wt% rare earth material to the mixed melt formed in step (2) and ensure uniform dispersion, and the rare earth material includes one or more of La, Nd, Re, Sm, Ce or Y kind;

(4) Carry out repair damage to the element of burning loss to adjust the chemical composition of alloy, and carry out remelting again with the same method of step (1) and evenly disperse into composite material melt;

(5) Turn on the high-purity argon gas, concentrate the airflow from one path to the atomization nozzle, maintain the atomization pressure and power, and the evenly mixed composite material melt flows out from the infusion tube, falls freely for a certain distance, and is broken under the action of high-pressure gas into Small spherical liquid droplets are quickly condensed into spherical powder particles to obtain spherical metal-based rare earth nanocomposite powders.

Preferably, the light metal is aluminum, lithium, magnesium, titanium or alloys thereof.

Preferably, in step (1), the vacuum degree in the crucible is controlled below 6.0×10 ^-3 Pa, the pressure of argon gas is 0-0.1 MPa, and the induced current intensity is 5-45A.

Preferably, the nano-material is nano-ceramic particles and/or nano-carbon materials, and the nano-ceramic particles are one or more of Al ₂ O ₃ , TiC, TiB, SiC, SiO ₂ , B ₄ C, and diamond , the nano-carbon material is one or more of carbon fibers, carbon nanotubes, and graphene.

Preferably, the size of the nano-ceramic particles and nano-carbon material is 0.1 nm-500 nm, and the purity is not lower than 99.9%.

Preferably, both step (2) and step (3) adopt electromagnetic stirring to ensure uniform dispersion of the melt, the rotating speed of electromagnetic stirring is 200-500r/min; the time of electromagnetic stirring is 10-30min.

Preferably, the particle size range of the rare earth material in step (3) is 0.1 nm-1.0 mm; the purity of the rare earth material is not lower than 99.9%.

Preferably, the angle of the atomizing nozzle in step (5) is 30-60°; the nozzle gap is 0.5-1.0mm; the atomizing pressure of the air nozzle is 2.0-8.0MPa; the power during atomization is 25-60kW.

Preferably, the melt flowing out of the infusion tube in step (5) falls 50-200 mm and is broken into small spherical droplets under the action of high-pressure gas.

2. The spherical metal-based rare earth nanocomposite powder prepared according to the preparation method.

The beneficial effects of the present invention are:

1. Compared with the prior art, the present invention obtains light metal-based rare earth ceramic composite spherical powder through vacuum induction smelting combined with gas atomization, which solves the problem that nanomaterials tend to agglomerate when two materials are mixed by mechanical force such as ball milling, thereby Lead to the problem of uneven distribution of composition and particle size.

2. Adding ceramic nanoparticles into the light metal melt can combine the high strength, high hardness, high melting point of ceramic particles and the toughness and thermal conductivity of the metal matrix, which can solve the requirements of contemporary industry for materials in high temperature, high speed, severe wear, The challenge of working in highly corrosive environments.

3. Due to the addition of rare earth materials into the light metal melt, the problems of poor wettability and thermal property differences between the ceramic phase and the light metal matrix phase are solved, so that the obtained light metal ceramic composite 3D printed structural parts have good interface bonding and Excellent mechanical properties. Rare earth materials play the role of purifying agent and nucleating agent in the crystallization process of the melt, which can effectively refine the grains, eliminate the segregation of the second phase, and improve the comprehensive mechanical properties of the material.

4. Since light metals such as aluminum, magnesium, and titanium have high laser reflectivity to laser light, it is usually difficult for low-power lasers to completely melt them. The addition of rare earth materials and nano-ceramic particles can increase the light metal powder’s absorption rate of laser light, thereby Play the role of reducing energy consumption and improving processing efficiency.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Fig. 1 is the preparation flowchart of the spherical light metal-based rare earth nanocomposite powder that can be used for three-dimensional printing manufacture;

Figure 2 shows the microhardness distribution diagram of the three-dimensional printing test using aluminum alloy powder;

Figure 3 shows the microhardness distribution diagram of the three-dimensional printing test using aluminum-based rare earth nanocomposite powder;

Figure 4 shows the picture of the product printed in 3D using aluminum-based rare earth nanocomposite powder as raw material.

detailed description

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

With reference to the preparation flow chart shown in Figure 1, the present invention enumerates following three preferred embodiments:

Example 1

The preparation method of the spherical light metal-based rare earth nanocomposite powder that can be used for three-dimensional printing is as follows:

(1) Add aluminum alloy to the crucible of the induction furnace, vacuumize the crucible and fill it with argon gas, adjust the induction current heating to melt the light metal raw material into a liquid melt, control the vacuum degree in the crucible below 6.0×10-3Pa, the argon gas The pressure is 0.05MPa; the intensity of the induced current is 40A;

(2) Control the temperature of the light metal melt to be 50-100°C higher than its melting point, add 15wt% nanomaterials to the metal melt under electromagnetic stirring and ensure uniform dispersion to form a mixed melt, and adjust the induced current intensity to 20A , the nanomaterial is TiC particles and carbon nanotubes with a mass ratio of 1:1, and the size of the TiC particles and carbon nanotubes is 0.5 to 1.0 nm;

(3) Add 0.5wt% rare earth material to the mixed melt formed in step (2) and ensure uniform dispersion, the rare earth material is Re with a particle size of 0.1nm-1.0mm, and the purity is higher than 99.9%;

(4) Carry out repair damage to the element of burning loss to adjust the chemical composition of alloy, and carry out remelting again with the same method of step (1) and evenly disperse into composite material melt;

(5) Turn on the high-purity argon gas, concentrate the airflow from one path to the atomization nozzle, maintain the atomization pressure and power, and the uniformly mixed composite material melt flows out from the infusion tube, falls freely for 100mm, and is broken into a spherical shape under the action of high-pressure gas Small droplets, and quickly condense into spherical powder particles to obtain spherical metal-based rare earth nanocomposite powders. The atomization nozzle angle is 45°; the nozzle gap is 1.0mm; the atomization pressure of the air nozzle is 3.0MPa; the power during atomization is 50kW .

Example 2

The preparation method of the spherical light metal-based rare earth nanocomposite powder that can be used for three-dimensional printing is as follows:

(1) Put the titanium alloy into the crucible of the induction furnace, evacuate the crucible and fill it with argon gas, adjust the induction current heating to melt the light metal raw material into a liquid melt, control the vacuum degree in the crucible below 6.0×10-3Pa, and the argon gas The pressure is 0.1MPa; the intensity of the induced current is 5A;

(2) Control the temperature of the light metal melt to be 50-100°C higher than its melting point, add 20wt% nanomaterials to the metal melt under electromagnetic stirring and ensure uniform dispersion to form a mixed melt, and adjust the induced current intensity to 5A , the nanomaterial is SiC particles and carbon fibers with a mass ratio of 2:1, and the size of the SiC particles and carbon fibers is 0.5-1.0 nm;

(3) Add 0.5wt% rare earth material to the mixed melt formed in step (2) and ensure uniform dispersion, the rare earth material is La with a particle size of 0.1nm-1.0mm, and the purity is higher than 99.9%;

(4) Carry out repair damage to the element of burning loss to adjust the chemical composition of alloy, and carry out remelting again with the same method of step (1) and evenly disperse into composite material melt;

(5) Turn on the high-purity argon gas, concentrate the airflow from one path to the atomization nozzle, maintain the atomization pressure and power, and the evenly mixed composite material melt flows out from the infusion tube, falls freely for 50mm, and is broken into a spherical shape under the action of high-pressure gas Small liquid droplets, and quickly condense into spherical powder particles to obtain spherical metal-based rare earth nanocomposite powders. The atomization nozzle angle is 30°; the nozzle gap is 0.5mm; the atomization pressure of the air nozzle is 2.0MPa; the power during atomization is 25kW .

Example 3

The preparation method of the spherical light metal-based rare earth nanocomposite powder that can be used for three-dimensional printing is as follows:

(1) Put the aluminum alloy into the crucible of the induction furnace, evacuate the crucible and fill it with argon gas, adjust the induction current to heat the light metal raw material to melt into a liquid melt, control the vacuum degree in the crucible below 6.0×10 ^-3 Pa, and argon gas The pressure is 0.02MPa; the control induction current intensity is 45A;

(2) Control the temperature of the light metal melt to be 50-100°C higher than its melting point, add 5wt% nanomaterials to the metal melt under electromagnetic stirring and ensure uniform dispersion to form a mixed melt, and adjust the induced current intensity to 25A , the nanomaterial is _SiO2 particles and graphene with a mass ratio of 1:2, and the size of the _SiO2 particles and graphene is 0.5-1.0nm;

(3) Add 1.0wt% rare earth material to the mixed melt formed in step (2) and ensure uniform dispersion, the rare earth material is Sm with a particle size of 0.1nm-1.0mm, and the purity is higher than 99.9%;

(4) Carry out repair damage to the element of burning loss to adjust the chemical composition of alloy, and carry out remelting again with the same method of step (1) and evenly disperse into composite material melt;

(5) Turn on the high-purity argon gas, concentrate the airflow from one path to the atomization nozzle, maintain the atomization pressure and power, and the uniformly mixed composite material melt flows out from the infusion tube, falls freely for 100mm, and is broken into a spherical shape under the action of high-pressure gas Small droplets, and quickly condense into spherical powder particles to obtain spherical metal-based rare earth nanocomposite powders. The atomization nozzle angle is 60°; the nozzle gap is 0.1mm; the atomization pressure of the air nozzle is 8.0MPa; the power during atomization is 60kW .

The aluminum alloy powder and the aluminum-based rare earth nanocomposite powder prepared in Example 1 were respectively subjected to laser printing tests, and the microhardness distribution diagrams shown in Figure 2 and Figure 3 were respectively obtained. Figure 2 shows that the energy input of different laser printing conditions, the microhardness distribution of aluminum alloy powder 3D printed parts; Figure 3 shows the microhardness distribution of the aluminum-based rare earth nanocomposite powder 3D printed parts prepared in Example 1 under different laser printing energy input conditions.

Comparing Figure 2 and Figure 3, the hardness of aluminum alloy powder 3D printing fluctuates greatly, and the highest hardness is about HV130. The fluctuation of microhardness is small, and the hardness value has been significantly improved, the maximum hardness value can reach HV145, and the microhardness has increased by about 12%. This shows that the nano-ceramic particles can be uniformly dispersed in the aluminum matrix through the method of the present invention, thereby playing the role of dispersion strengthening, and the small hardness fluctuation indicates that the uniformity of the distribution of the nano-ceramic particles has been improved.

Further, under the same three-dimensional printing process parameters, the aluminum alloy and the aluminum-based rare earth nanocomposite three-dimensional printing molded parts prepared in Example 1 were tested for tensile properties, and the test data shown in Table 1 were obtained:

Table 1 Performance test of specimens printed with aluminum alloy and aluminum-based rare earth nanocomposites

From the data shown in Table 1, it can be seen that under the same three-dimensional printing process parameters, the tensile properties (comprising tensile strength, yield strength and elongation) as shown in Table 1. The ultimate tensile strength of the aluminum alloy 3D printed parts is 356MPa, the yield strength is 257MPa, and the elongation is 4.3%). In comparison, the ultimate tensile strength of the aluminum-based rare earth nanocomposite 3D printing molded part prepared by the present invention reaches 412MPa, the yield strength is 302MPa, and the elongation is 5.5%. It can be seen that the three-dimensional printed parts of aluminum-based rare earth nanocomposites prepared by the present invention have more excellent strength and toughness.

Fig. 4 is a photograph of a three-dimensionally printed aluminum alloy formed part with a complex structure using the aluminum-based rare earth nanocomposite powder prepared by the present invention as a raw material under optimized process conditions. The structure in Figure 4(a) has curved surfaces with non-uniform thickness, the minimum thickness of the thin-walled curved surface is 1 mm, and the surface is dense and smooth. Figure 4(b) has overhanging structures and assembly holes that are difficult to achieve in 3D printing. Figure 4(c) is a new type of aluminum alloy nanocomposite engine cylinder head printed for a domestic automobile company. The product has large parts, complex outer contour and internal structure, large internal stress during processing, and many supports. Figure 4(d) and (e) are the printed aerospace-grade aluminum alloy brackets for small satellites. The difficulty in forming them lies in the support loading and the overlapping of the growth surface.

It can be seen that the light metal-based rare earth nanocomposite powder prepared by the present invention has been verified by three-dimensional printing processes many times, meets the requirements of three-dimensional printing for metal-based composite powder materials, and has a good technical application prospect.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (10)

1. a kind of preparation method of spherical metal base rare earth nano composite powder available for 3 D-printing, it is characterised in that bag Include following steps：

(1) light metal raw material is added in the crucible of electric induction furnace, crucible is vacuumized into applying argon gas, regulation and control induced-current heating makes Light metal raw material is melted into liquid melts；

(2) 0-20.0wt% nano materials are added to by control light metal melt temperature higher than in the range of 50~100 DEG C of its fusing point In metal bath and ensure dispersed formation blend melt, and regulate and control induction current intensity for 5~25A；

(3) 0-1.0wt% rare earth material is added in the blend melt formed to step (2) and ensures dispersed, it is described dilute Soil material includes the one or more in La, Nd, Re, Sm, Ce or Y；

(4) element of scaling loss is carried out mending damage to adjust the chemical composition of alloy, and one is carried out again with the same method of step (1) Secondary remelting is simultaneously dispersed into Composite Melt；

(5) high-purity argon gas is opened, atomizer is focused on by air-flow all the way, atomization air pressure and power is kept, well mixed answers Condensation material melt is flowed out by woven hose, and spherical droplet is crushed under gases at high pressure effect after the segment distance that freely lands, And rapid condensation globulate powder particle, obtain spherical metal base rare earth nano composite powder.

2. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to right will go 1 Method, it is characterised in that the light metal is aluminium, lithium, magnesium, titanium or its alloy.

3. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to claim 1 Method, it is characterised in that vacuum is 6.0 × 10 in step (1) control crucible^-3Below Pa, the pressure 0-0.1MPa of argon gas, sensing Current strength 5-45A.

4. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to claim 1 Method, it is characterised in that the nano material is nano-ceramic particle and/or nano-carbon material, the nano-ceramic particle is Al₂O₃、TiC、TiB、SiC、SiO₂、B₄One or more in C, diamond, the nano-carbon material is carbon fiber, carbon nanometer Pipe, the one or more of graphene.

5. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to claim 4 Method, it is characterised in that the size of the nano-ceramic particle and nano-carbon material is 0.1nm-500nm, purity is not less than 99.9%.

6. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to claim 1 Method, it is characterised in that step (2) and step (3) ensure that melt is dispersed by the way of electromagnetic agitation, electromagnetic agitation Rotating speed is 200-500r/min；The electromagnetic agitation time is 10-30min.

7. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to claim 1 Method, it is characterised in that the size scope of step (3) described rare earth material is 0.1nm-1.0mm；The purity of rare earth material is not Less than 99.9%.

8. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to claim 1 Method, it is characterised in that step (5) the atomizer angle is 30-60 °；Nozzle gap 0.5-1.0mm；Air nozzle atomization gas Press 2.0-8.0MPa；Power 25-60kW during atomization.

9. the preparation side of a kind of spherical metal base rare earth nano composite powder available for 3 D-printing according to claim 1 Method, it is characterised in that be crushed into after the melt landing 50-200mm that step (5) is flowed out by woven hose under gases at high pressure effect Spherical droplet.

10. the spherical metal base rare earth nano composite powder being made according to any one of claim 1~9 preparation method.