CN104668553B - A kind of alloyed powder printing metal parts for direct 3D and preparation method thereof - Google Patents

Abstract

The invention proposes an alloy powder for direct 3D printing of metal parts, which is characterized in that: iron-based alloy microspheres formed by bonding nano-aluminum to the surface of iron oxide through a thin layer of tin powder, the particle size of the microspheres At 2-10 microns, the sphericity is greater than 95%, the iron oxide in the alloy is 60-70 parts by weight, the nano-aluminum is 30-40 parts by weight, and the tin powder is 0.1-0.5 parts by weight. Can be used directly for 3D printing metal parts. When used for direct 3D printing of metal parts, through the gradual reduction of aluminum to iron oxides, the structural deformation caused by the direct melting of the metal is overcome, and the cooling crystallization is uniform, and the formed alumina improves the strength of the molded part and the porosity of the product Reduced, with good compactness, can be used for direct 3D printing of high-precision, complex-shaped metal parts.

Description

one for direct 3D Alloy powder for printing metal parts and preparation method thereof

technical field

The invention belongs to the field of 3D printing manufacturing materials, and in particular relates to an alloy powder which can directly use 3D printing to manufacture high-strength and high-density metal parts, and further relates to a preparation method of the alloy powder.

Background technique

3D printing technology is a rapid additive manufacturing technology that generates three-dimensional entities by increasing the accumulation of materials layer by layer. It not only overcomes the loss caused by traditional subtractive manufacturing, but also makes product manufacturing more intelligent, more accurate and more efficient. Especially when it comes to high-end manufacturing of complex shapes, 3D printing technology shows great advantages. 3D printing technology is a high-tech manufacturing technology with industrial revolution significance, which represents a new trend in the development of the world's manufacturing industry. In recent years, the application of 3D printing has continued to expand, mainly using resin and paraffin as raw materials for rapid prototyping. The ultimate development of 3D printing is to be applied in the high-end industrial field. Resin plastics cannot meet the needs of high-end industrial 3D printing. Therefore, 3D printing materials are gradually developing from resin plastics to metal materials.

Metal powder is used for 3D printing, which requires high metal powder. Generally, metal powder must meet the characteristics of fine powder particle size, narrow particle size distribution, high sphericity, good fluidity, and high bulk density. However, these properties are difficult to meet at the same time, so 3D printing metal powder is difficult to meet the needs of high-precision printing. As a result, metal parts manufactured by 3D printing metal powder through selective laser sintering generally have problems such as low strength, low precision, and poor surface quality. For example, the physical and chemical properties of materials, laser parameters and sintering process parameters affect the sintering process, molding accuracy and quality. During the forming process of parts, due to the influence of various material factors and process factors, various metallurgical defects such as cracks, deformation, pores, and uneven organization will occur in sintered parts.

The reason why the 3D printing manufacturing technology of metal materials is difficult is that the melting point of metal is relatively high, which involves various physical processes such as solid-liquid phase transition of metal, surface diffusion and heat conduction. Whether the crystal structure generated during the melting and cooling process is good, whether the entire test piece is uniform, internal impurities and the size of the pores will all cause stress changes in metal parts. Therefore, the current use of 3D printing to manufacture metal products from metal powder mostly uses indirect preparation methods to pre-bond the metal powder and then sinter it. Such as:

Chinese Invention Patent Application No. 200510020015.5 discloses a preparation method of laser sintering rapid prototyping materials. In this method, binder phenolic resin is pulverized and mixed with metal or alloy powder, and the selective laser sintering rapid manufacturing of metal parts is realized through the binder. This indirect molding method will form a large number of cavities due to sintering, which requires post-impregnation treatment to improve strength.

China Invention Patent Application No. 201310605634.5 discloses a low-power laser sintering metal 3D printing product production method, which uses metal powder materials to heat and plastically form adhesives to prepare 3D metal printing raw material mixtures with low melting points. Due to the metal powder A thin layer of thermoplastic binder is formed on the surface of the particles. Through the low-power selective laser sintering or electron beam sintering method of 3D printers, the metal powder material is melted at low temperature by the surface layer of thermoplastic binder-cooling, bonding and solidifying process, and the layers are piled up and formed. The metal part is a green body formed by indirect bonding and requires subsequent processing. And because the adhesive introduced is a kind of impurity for the metal product, it will have an adverse effect on the mechanical properties of the product.

Chinese invention patent application number 201410028642.2 discloses a metal powder for 3D printers. By reducing the particle size of the metal powder to the submicron level, the melting point is low and the melting speed is fast, which can improve the printing speed of the metal 3D printer and the accuracy of the printed component. The submicron metal powder reduces the melting temperature by reducing the particle size, but because it is a submicron metal powder formed by bonding, it is easy to deform the metal product during the melting and cooling process due to the lack of support when used for direct printing.

According to the above, the 3D printing metal powder is less compact in the manufacture of metal products through indirect bonding, and subsequent impregnation and filling treatment of the formed pores is required, resulting in damage to the strength of the metal product. When directly formed by 3D printing laser melting technology, the terminal metal product can be directly made into a metal entity with a metallurgical structure. It is difficult to obtain high-precision, high-density, and high-strength metal products when manufacturing metal products.

Contents of the invention

In view of the defect that metal powder is difficult to directly manufacture high-precision, high-density, high-strength metal parts through 3D printing, the present invention proposes an alloy powder for direct 3D printing of metal parts. The alloy powder is an iron-based alloy microsphere formed by bonding nano-aluminum on the surface of iron oxide through a layer of thin tin powder. The particle size of the microsphere is 2-10 microns, and the sphericity is greater than 95%. Can be used directly for 3D printing metal parts. When used for direct 3D printing of metal parts, through the gradual reduction of aluminum to iron oxides, the structural deformation caused by the direct melting of the metal is overcome, and the cooling crystallization is uniform, and the formed alumina improves the strength of the molded part and the porosity of the product Reduced, with good compactness, it can be used for direct printing of metal parts with high precision and complex shapes.

An alloy powder for direct 3D printing of metal parts is realized through the following technical scheme:

An alloy powder for direct 3D printing of metal parts, characterized in that: iron-based alloy microspheres formed by bonding nano-aluminum on the surface of iron oxides through a thin layer of tin powder, the particle size of the microspheres is between 2- 10 microns, sphericity greater than 95%, 60-70 parts by weight of iron oxide in the alloy, 30-40 parts by weight of nano-aluminum, and 0.1-0.5 parts by weight of tin powder.

The iron oxide has an average particle size of 500nm, a purity of 99.9%, a specific surface area of 50-80m ² /g, and a spherical crystal phase.

The average particle size of the nano aluminum is 10-20nm, the purity is 99.9%, and the specific surface area is 90-120m ² /g.

Said tin powder has an average particle size of 10 μm and a purity of over 99.5%.

An alloy powder for direct 3D printing of metal parts, which is characterized in that: through the gradual reduction of aluminum to iron oxides, without proppant and binder, it overcomes the structural deformation caused by direct metal melting and molding, and can be directly processed by 3D Print and manufacture the final metal parts, which have high precision, high density, and high strength, without subsequent hole filling treatment.

The present invention is a method for preparing alloy powder for direct 3D printing of metal parts, which is characterized in that it is carried out in the following manner:

1) Put 60-70 parts by weight of spherical fine iron oxide in a high-speed dispersing equipment, set the temperature of the dispersing equipment at 200-240°C, carry out high-speed stirring and dispersing at 900-1500rpm, and control the dispersion time at 5-15min. After the iron oxide is heated and stabilized, add 0.1-0.5 parts by weight of tin powder, and continue to stir for 20-30 minutes to completely melt the tin powder and coat it on the surface of the spherical fine iron oxide;

2) Add 30-40 parts by weight of nano-aluminum to the coated spherical fine iron oxide obtained in step 1), set the temperature of the dispersing equipment at 180-220°C, set the vacuum degree at 0.03-0.05MPa, and set it at 400- At a speed of 800rpm, the aluminum powder is uniformly dispersed and coated on the surface of spherical fine iron oxide, and the dispersion time is controlled at 5-15 minutes to obtain alloy powder coated with aluminum powder and spherical fine iron oxide;

3) Send the alloy powder obtained in step 2) into a cooler protected by argon gas for cooling and sieving to obtain alloy powder directly used for 3D printing metal parts.

In the above preparation method, the high-speed dispersing equipment described in step 1) is a high-speed mixer equipped with disc blades.

In the above preparation method, the cooler described in step 3) is a powerful argon gas flow cooler, which cools the alloy powder by high-speed argon gas flow, and pulverizes part of the cohesive alloy powder through the impact of the gas flow and the formation of a vortex, and sieves it by rotating Alloy powder with uniform particle size is obtained.

The present invention is an alloy powder for direct 3D printing of metal parts. It is an iron-based alloy microsphere formed by bonding nano-aluminum to the surface of iron oxide through a layer of thin tin powder. The particle size of the powder is 2-10 microns. Evenly distributed, the alloy powder does not add a non-metallic binder, which has no effect on the raw materials, and the composition will not be lost when the powder flows or melts rapidly in the subsequent processing process. During laser sintering, the aluminum powder gradually reduces iron oxide to prevent iron Rapid solidification, the formed alumina improves the strength of the molded part, forms a dense metal part, overcomes the structural deformation caused by the direct melting of the metal, and cools and crystallizes uniformly, ensuring the uniformity and uniform distribution of the components, which can be used for high precision , Direct printing of metal parts of complex shapes.

The invention is an alloy powder for direct 3D printing of metal parts, which has good dispersibility and powder transportability. It is preheated to 400°C through the nozzle of the 3D printer, and at a scanning speed of 20-25mm/s, it can be used at 800- Iron oxide is converted into iron during laser sintering at 1000°C, and the converted alumina is used as a support, which improves the molding accuracy of the product and can be used to prepare precision metal parts with complex components. The tensile strength of the printed product is greater than 280MPa, and the density is greater than 6.4×10 ³ kg/m ³ , with good strength and compactness.

The present invention is a method for preparing alloy powder for direct 3D printing of metal parts. Compared with the prior art, its outstanding features and excellent effects are:

1. The present invention is an alloy powder for direct 3D printing of metal parts. The alloy powder is formed by coating spherical fine iron oxide with aluminum powder. The alloy powder does not add non-metallic binder, and the aluminum powder gradually reduces iron oxide during laser sintering , to prevent rapid solidification of iron, directly formed into final metal parts, without subsequent hole filling treatment.

2. An alloy powder for direct 3D printing of metal parts according to the present invention. The particle size of the powder is 2-10 microns, the sphericity is greater than 95%, and it has good dispersion and powder transportability. It is preheated through the nozzle of the 3D printer , at a scanning speed of 20-25mm/s, the converted alumina during laser sintering is used as a support, which overcomes deformation and cracking during the molding process, prevents internal defects, and can directly prepare precision metal parts with complex components by 3D printing. The forming precision of the product is improved, and the aluminum oxide is evenly distributed in the formed part to form a high-density, high-strength metal part.

3. A method for preparing alloy powder for direct 3D printing of metal parts in the present invention, using tin powder as a connecting material, and using conventional dispersion equipment at a temperature of 200-240°C to evenly coat aluminum powder on the surface of iron oxide powder , simplifies the preparation process of alloy powder, improves the uniformity of the material, and makes the metal melting, reduction reaction, and cooling crystallization more stable during 3D printing and sintering.

detailed description

The present invention will be further described in detail through specific embodiments below, but it should not be understood that the scope of the present invention is limited to the following examples. Without departing from the idea of the above-mentioned method of the present invention, various replacements or changes made according to common technical knowledge and conventional means in this field shall be included within the scope of the present invention.

Example 1

1) Put 60 parts by weight of spherical fine iron oxide in a high-speed dispersion equipment, set the temperature of the dispersion equipment at 240°C, perform high-speed stirring and dispersion at 900 rpm, and control the dispersion time at 10 minutes. After the spherical fine iron oxide is heated and stabilized, add 0.1 Tin powder by weight, continue to stir for 20 minutes to make the tin powder completely melted and coated on the surface of spherical fine iron oxide;

2) Add 40 parts by weight of nano-aluminum to the coated spherical fine iron oxide obtained in step 1), set the temperature of the dispersion equipment to 220°C, set the vacuum degree to 0.03MPa, and disperse the aluminum powder evenly at a speed of 400rpm in a vacuum state Adhesive coating on the surface of spherical fine iron oxide, the dispersion time is controlled at 15 minutes, and the alloy powder of spherical fine iron oxide coated with aluminum powder is obtained;

3) Send the alloy powder obtained in step 2) into a cooler protected by argon for cooling and sieving to obtain alloy powder directly used for 3D printing metal parts.

The alloy powder obtained in embodiment 1 is passed through detection: the performance data is as follows: Test items Test results The average particle size 5μm Sphericity (80%) ≥96% Powder Flowability (BEF) 28mJ

The nozzle of the 3D printer is preheated to 400°C, at a scanning speed of 20mm/s, iron oxide is converted into iron during laser sintering at 850°C, and the transformed alumina is used as a support to obtain a complex part of the bushing. Through the test, the tensile strength is 320MPa, the density is 7.1×10 ³ kg/m ³ , and the hardness is 166HBW.

Example 2

1) Put 65 parts by weight of spherical fine iron oxide in a high-speed dispersion equipment, set the temperature of the dispersion equipment at 200°C, perform high-speed stirring and dispersion at 1500 rpm, and control the dispersion time at 15 minutes. After the spherical fine iron oxide is heated and stabilized, add 0.3 Tin powder by weight, continue to stir for 25 minutes to make the tin powder completely melt and apply on the surface of spherical fine iron oxide;

2) Add 30 parts by weight of nano-aluminum to the coated spherical fine iron oxide obtained in step 1), set the temperature of the dispersion equipment to 220°C, set the vacuum degree to 0.04MPa, and disperse the aluminum powder evenly at a speed of 800rpm in a vacuum state Adhesive coating on the surface of spherical fine iron oxide, the dispersion time is controlled at 15 minutes, and the alloy powder of spherical fine iron oxide coated with aluminum powder is obtained;

3) Send the alloy powder obtained in step 2) into a cooler protected by argon gas for cooling and sieving to obtain alloy powder directly used for 3D printing metal parts.

The alloy powder obtained in embodiment 2 is passed through detection: the performance data is as follows: Test items Test results The average particle size 8μm Sphericity (80%) ≥95% Powder Flowability (BEF) 31mJ

The nozzle of the 3D printer is preheated to 400°C, at a scanning speed of 22mm/s, iron oxide is converted into iron during laser sintering at 900°C, and the converted alumina is used as a support to obtain a coupling. Through the test, the tensile strength is 360MPa, the density is 7.3×10 ³ kg/m ³ , and the hardness is 170HBW.

Example 3

1) Put 70 parts by weight of spherical fine iron oxide in a high-speed dispersion equipment, set the temperature of the dispersion equipment at 230°C, perform high-speed stirring and dispersion at 1000 rpm, and control the dispersion time at 8 minutes. After the spherical fine iron oxide is heated and stabilized, add 0.5 Tin powder by weight, continue to stir for 30 minutes to make the tin powder completely melted and coated on the surface of spherical fine iron oxide;

2) Add 35 parts by weight of nano-aluminum to the coated spherical fine iron oxide obtained in step 1), set the temperature of the dispersion equipment to 180°C, set the vacuum degree to 0.05MPa, and disperse the aluminum powder evenly at a speed of 500rpm in a vacuum state Adhesive coating on the surface of spherical fine iron oxide, the dispersion time is controlled at 12 minutes, and the alloy powder of spherical fine iron oxide coated with aluminum powder is obtained;

3) Send the alloy powder obtained in step 2) into a cooler protected by argon gas for cooling and sieving to obtain alloy powder directly used for 3D printing metal parts.

The alloy powder obtained in embodiment 3 is passed through detection: performance data is as follows: Test items Test results The average particle size 10μm Sphericity (80%) ≥98% Powder Flowability (BEF) 22mJ

The nozzle of the 3D printer is preheated to 400°C, and at a scanning speed of 20mm/s, iron oxide is converted to iron during laser sintering at 1000°C, and the converted alumina is used as a support to obtain a heterogeneous gland plate with a complex shape. . Through the test, the tensile strength is 310MPa, the density is 6.9×10 ³ kg/m ³ , and the hardness is 158HBW.

Example 4

1) Put 65 parts by weight of spherical fine iron oxide in the high-speed dispersion equipment, set the temperature of the dispersion equipment at 220°C, perform high-speed stirring and dispersion at 1200 rpm, and control the dispersion time at 10 minutes. After the spherical fine iron oxide is heated and stabilized, add 0.4 Tin powder by weight, continue to stir for 25 minutes to make the tin powder completely melt and apply on the surface of spherical fine iron oxide;

2) Add 40 parts by weight of nano-aluminum to the coated spherical fine iron oxide obtained in step 1), set the temperature of the dispersion equipment to 220°C, set the vacuum degree to 0.03MPa, and disperse the aluminum powder evenly at a speed of 450rpm in a vacuum state Adhesive coating on the surface of spherical fine iron oxide, the dispersion time is controlled at 5 minutes, and the alloy powder of spherical fine iron oxide coated with aluminum powder is obtained;

3) Send the alloy powder obtained in step 2) into a cooler protected by argon gas for cooling and sieving to obtain alloy powder directly used for 3D printing metal parts.

The alloy powder obtained in embodiment 4 is passed through detection: the performance data is as follows: Test items Test results The average particle size 4μm Sphericity (80%) ≥96% Powder Flowability (BEF) 34mJ

The nozzle of the 3D printer is preheated to 400°C, at a scanning speed of 25mm/s, iron oxide is converted into iron during laser sintering at 920°C, and the converted alumina is used as a support to obtain a special-shaped sleeve. Through the test, the tensile strength is 280MPa, the density is 6.5×10 ³ kg/m ³ , and the hardness is 173HBW.

Example 5

1) Put 60 parts by weight of spherical fine iron oxide in a high-speed dispersion equipment, set the temperature of the dispersion equipment at 240°C, perform high-speed stirring and dispersion at 1500 rpm, and control the dispersion time at 15 minutes. After the spherical fine iron oxide is heated and stabilized, add 0.5 Tin powder by weight, continue to stir for 30 minutes to make the tin powder completely melted and coated on the surface of spherical fine iron oxide;

2) Add 30 parts by weight of nano-aluminum to the coated spherical fine iron oxide obtained in step 1), set the temperature of the dispersion equipment to 220°C, set the vacuum degree to 0.05MPa, and disperse the aluminum powder evenly at a speed of 400rpm in a vacuum state Adhesive coating on the surface of spherical fine iron oxide, the dispersion time is controlled within 5-15 minutes, and the alloy powder of spherical fine iron oxide coated with aluminum powder is obtained;

3) Send the alloy powder obtained in step 2) into a cooler protected by argon gas for cooling and sieving to obtain alloy powder directly used for 3D printing metal parts.

The alloy powder obtained in embodiment 5 is passed through detection: performance data is as follows: Test items Test results The average particle size 2μm Sphericity (80%) ≥95% Powder Flowability (BEF) 35mJ

The nozzle of the 3D printer is preheated to 400°C, at a scanning speed of 20mm/s, iron oxide is converted into iron during laser sintering at 1000°C, and the converted alumina is used as a support to obtain a mold. Through the test, the tensile strength is 296MPa, the density is 6.4×10 ³ kg/m ³ , and the hardness is 157HBW.

Claims (6)

1. the alloyed powder printing metal parts for direct 3D, it is characterized in that: the ferrous alloy microballoon formed by the oxide surface that one layer of thin glass putty is bonded in iron by nano aluminum, the particle diameter of microballoon is at 2-10 micron, sphericity is more than 95%, in alloy, the weight portion of iron oxide is 60-70 part, the weight portion of nano aluminum is 30-40 part, and the weight portion of glass putty is 0.1-0.5 part.

2., according to the alloyed powder printing metal parts for direct 3D a kind of described in claim 1, it is characterized in that: described iron oxide average grain diameter is 500nm, purity 99.9%, specific surface area 50-80 m²/ g, crystalline phase spherical in shape.

3., according to the alloyed powder printing metal parts for direct 3D a kind of described in claim 1, it is characterized in that: described nano aluminum average grain diameter is 10-20nm, purity 99.9%, specific surface area 90-120 m²/g。

4., according to the alloyed powder printing metal parts for direct 3D a kind of described in claim 1, it is characterized in that: described glass putty average grain diameter 10 μm, purity more than 99.5%.

5. the preparation method of a kind of alloyed powder printing metal parts for direct 3D described in claim 1, is characterized in that carrying out as follows:

1) the spherical fine iron oxide of 60-70 weight portion is placed in high-speed dispersion equipment, dispersing apparatus temperature is set and is 200-240 DEG C, carry out the high-speed stirred dispersion of 900-1500rpm, jitter time controls at 5-15min, until spherical fine iron oxide by after thermally-stabilised, add the glass putty of 0.1-0.5 weight portion, continue stirring and within 20-30 minute, make glass putty be completely melt to be coated in spherical fine iron oxide surface；

2) nano aluminum of 30-40 weight portion is added the spherical fine iron oxide of coating that step 1) obtains, dispersing apparatus temperature is set and is 180-220 DEG C, vacuum is set to 0.03-0.05MPa, it is sticked and coated on spherical fine iron oxide surface by dispersed for aluminium powder under vacuum conditions with the rotating speed of 400-800rpm, jitter time controls at 5-15min, obtains by the alloyed powder of the spherical fine iron oxide of coated aluminum powder；

3) by step 2) alloyed powder that obtains sends into and obtains being directly used in 3D and print the alloyed powder of metal parts by carrying out in the cooler of argon shield cooling down, sieve.

A kind of preparation method of the alloyed powder printing metal parts for direct 3D, it is characterized in that: the cooler described in step 3) is strength argon stream cooler, made alloyed powder cool down by high speed argon stream, and the alloyed powder of residual adhesion is pulverized by airflow strikes and formation vortex, is got by rotary screen the alloyed powder of uniform particle diameter.