Method for heat treatment of a powder for selective laser sintering

Abstract

The application discloses a kind of selective laser sintering powder heat treatment method, comprising the following steps: step one: high molecular powder is evenly laid on substrate;Step two: nanometer particle is sprayed on high molecular powder surface using spray head, then wavelength 500-1600nm fiber laser is used to scan high molecular powder, high molecular powder is heated, and high molecular powder surface appears melting state;Step three: after step two processing, high molecular powder is cooled to below glass transition temperature, then high molecular powder is scraped from substrate;Step four: high molecular powder with nanometer particle adhered obtained in step three is obtained by sieving and air classification after processing, and high molecular powder for selective laser sintering is obtained.The nanometer particle is adhered on the surface of high molecular powder, so that the performance of high molecular powder shows higher stability and consistency during repeated use, which is beneficial to improve the quality and performance of sintered product.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a method for powder heat treatment for selective laser sintering. Background Technology

[0002] Selective laser sintering (SLS) is a mainstream rapid prototyping method. This technology does not require the use of tools for processing. It only requires the creation of a computer 3D model of the target part, followed by slicing the 3D model using layering software, and finally obtaining a 3D solid by laser sintering multiple layers of powder.

[0003] In selective laser sintering (SLS), powders require high performance, including good flowability, light absorption, and thermal properties. To improve these characteristics, additives are typically added to the powder to enhance these properties. Nanoparticles are particularly effective in this regard. For example, nanoscale flow aids can adhere to the surface of micron-sized powders, acting as ball bearings; while nanoscale carbon black and other light absorbers can coat micron-sized polymer powders, enhancing the powder's absorption of laser energy.

[0004] However, due to their large specific surface area, polymer powders used in micron-sized selective laser sintering (SLS) readily adsorb nanoparticles. Conversely, due to their small specific surface area, polymer powders used in micron-sized SLS struggle to adsorb nanoparticles through physical stirring. Furthermore, polymer powders typically exhibit a normally distributed size distribution; during physical stirring, this leads to uneven nanoparticle coverage on the polymer surface, affecting powder flowability and SLS performance. Additionally, SLS equipment requires the use of scrapers or rollers to spread the powder onto the working cylinder for sintering. Moreover, repeated use involves screening and stirring, which can cause nanoparticles to detach, impacting powder performance. Therefore, maintaining stability and consistency during repeated use is a critical issue in SLS technology. Summary of the Invention

[0005] This invention provides a method for heat treatment of powders used in selective laser sintering, aiming to solve the problem of powder performance stability and consistency during powder reuse, thereby improving the quality and performance of the sintered product. The method includes the following steps:

[0006] Step 1: Evenly spread polymer powder on the substrate. The average particle size of the polymer powder is 40–180 μm, the particle size distribution is 0.5–2.0 μm, and the bulk density is 0.2–0.85 g / cm³. 3 This polymer powder has good flowability, which is beneficial for spreading it on the substrate.

[0007] Step Two: Nanoparticles are sprayed onto the surface of the polymer powder using a nozzle. Then, a fiber laser with a wavelength of 500–1600 nm is used to scan the polymer powder, heating it until the surface melts. The nanoparticles become embedded in the polymer powder and adhere to its surface. The fiber laser power is 30–800 W, the scanning line spacing is 0.1–1.0 mm, the scanning speed is 2–40 m / s, and the spot size is 50–2000 μm. The adhesion of the nanoparticles to the polymer powder surface enhances its performance.

[0008] Step 3: After the treatment in Step 2, the polymer powder is cooled to below the glass transition temperature, and then the polymer powder is scraped off from the substrate to obtain polymer powder with adhered nanoparticles.

[0009] Step 4: The polymer powder with adhered nanoparticles obtained in Step 3 is then subjected to sieving and air classification to obtain an average particle size of 38–165 μm, a particle size spacing of 0.5–1.9 μm, and a bulk density of 0.25–0.9 g / cm³. 3 Selective laser sintering of polymer powder, wherein the nanoparticles cover the surface of the polymer powder by 5% to 500%.

[0010] This invention heats polymer powder to a viscous flow state on its surface while maintaining a highly elastic state. This molten state on the surface, combined with the inherent elasticity of the polymer powder itself, allows nanoparticles to adhere to the polymer powder surface while preserving its original shape. This viscous flow state reduces surface porosity and makes the polymer powder more compact for solvent-precipitated powders, while promoting more regular shapes for powders prepared by cryogenic grinding.

[0011] In this invention, nanoparticles are adhered to the surface of polymer powder, and then the polymer powder is cooled to below the glass transition temperature to fix its entire state and prevent deformation when the polymer powder is scraped later.

[0012] Because of the viscous flow state on the surface of polymer powder, polymers in contact with each other can bond together. Simultaneously, small polymer powder particles can completely melt to form even smaller particles. Both large and small particles are detrimental to the reuse of the polymer powder. Therefore, it is necessary to remove large particles through sieving and small particles through air classification. Thus, the polymer powder obtained after sieving and air classification has better density and consistency, which can improve the quality and performance of selective laser sintered parts.

[0013] In step two of this invention, when the nanoparticles are nanomaterials capable of absorbing short-wavelength laser energy, a 500–1600 nm fiber laser is used for powder heating to better and more precisely control the melting of the polymer powder. The laser power is 30–800 W, the scanning line spacing is 0.1–1.0 mm, the scanning speed is 2–40 m / s, and the spot size is 50–2000 μm. Since polymers themselves have low absorption of 500–1600 nm wavelength fiber laser energy, and nanomaterials capable of absorbing short-wavelength laser energy are spectral absorbing materials, they can effectively absorb 500–1600 nm wavelength fiber laser energy, generating heat. This causes the surface of the polymer powder to melt, and because the polymer powder has a low thermal conductivity, only the surface melts, while the central part retains its original integrity. This absorption process is also very rapid, and the higher power of the fiber laser further improves processing efficiency. Simultaneously, the fiber laser has higher power and a faster scanning speed than the CO2 laser, resulting in faster powder heating efficiency.

[0014] Preferably, in step one, the polymer powder is evenly spread on the substrate using a roller or a scraper.

[0015] Preferably, the thickness of the polymer powder layer on the substrate in step one is 1.0 to 2.0 times the average particle size of the polymer powder in step one. This treatment aims to ensure that the polymer powder is uniformly spread on the substrate and to prevent the polymer powder from being affected by other powders.

[0016] Preferably, in step two, the coverage of nanoparticles on the surface of the polymer powder is 5 to 500%.

[0017] Preferably, in step two, the polymer powder is heated to 50–350°C and heat-treated for 1–20 seconds.

[0018] Preferably, the spray rate of the nozzle is 10-300 mg / s, the moving speed of the nozzle is 150-300 mm / s, and the width of the nanoparticles sprayed by the nozzle is 50-200 mm.

[0019] Preferably, in step two, cold nitrogen gas is introduced to cool the polymer powder to below the glass transition temperature, and the cooling rate is 5-10°C / s.

[0020] Preferably, in step three, the polymer powder is scraped off the substrate using a scraper.

[0021] Preferably, in step four, the polymer powder with adhered nanoparticles is sieved through a 20-200 mesh sieve.

[0022] Preferably, the nanoparticles have a particle size of 5–400 nm. The nanoparticles are one or more of metal nanoparticles and carbon nanoparticles; these nanoparticles can effectively improve the performance of the powder.

[0023] Preferably, the metal nanoparticles are gold nanoparticles, copper nanoparticles, silver nanoparticles, titanium nanoparticles, nickel nanoparticles, or aluminum nanoparticles.

[0024] Preferably, the carbon nanoparticles are carbon black, carbon nanotubes, or graphene.

[0025] Preferably, the polymer powder is polylactic acid (PLA), polyurethane (TPU), polyethylene (PE), polypropylene (PP), polystyrene (PS), nylon (PA), polycarbonate (PC), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or polyetheretherketone (PEEK) powder. These polymer powders have good properties and a wide range of applications.

[0026] The present invention provides a method for heat-treating powders for selective laser sintering, and the resulting polymer powders for selective laser sintering have the following advantages:

[0027] 1. Laser heating allows for precise control of the heating area, making it possible to heat and process materials at the microscale, thus achieving more accurate control. The laser heating process is typically rapid, enabling fast heating and cooling, which has significant advantages for specific processing applications such as laser sintering and laser heat treatment, helping to reduce the heat-affected zone and improve production efficiency.

[0028] 2. By spraying nanoparticles onto the surface of the polymer powder through a nozzle, the agglomeration of nanoparticles is reduced. This successfully adheres the nanoparticles to the polymer powder surface, enhancing the stability and consistency of the polymer powder, which is beneficial for improving the quality and performance of the finished product during repeated use. Simultaneously, this process solves the problem of dispersing large-particle-size nano-adultants using traditional physical stirring methods.

[0029] 3. A large amount of small-particle-size powder was removed through a refined heat treatment process, which effectively reduced the powder slinging and caking phenomenon that may occur during sintering, and improved the quality and efficiency of the finished product.

[0030] 4. The increased loose packing density of the powder makes it easier to handle and apply during selective laser sintering. Detailed Implementation

[0031] The present invention will be further described in detail below through specific embodiments.

[0032] Comparative Example 1

[0033] Step 1: Spread Nylon 12 (PA12) powder evenly onto the substrate using a roller. The PA12 powder has an average particle size of 60 μm, a particle size distribution of 1.0, and a loose packing density of 0.45 g / cm³. 3 .

[0034] Step 2: Carbon black with a particle size of 15nm is sprayed onto the surface of PA12 powder through a nozzle. The spraying rate of the nozzle is 20mg / s, the moving speed of the nozzle is 200mm / s, and the width of the nanoparticles sprayed by the nozzle is 100mm, so that the carbon black is uniformly dispersed on the surface of PA12 powder, and the coverage of carbon black on the surface of PA12 powder is 140%.

[0035] Step 3: Use a scraper to scrape the powder off the substrate to obtain PA12 powder with carbon black adhering to it.

[0036] Step 4: The PA12 powder with carbon black adhering to it obtained in Step 3 is sieved through a 100-mesh sieve and then subjected to air classification to obtain PA12 powder for selective laser sintering. The PA12 powder for selective laser sintering has a particle size of 59 μm, a particle size distribution of 0.9 mm, and a loose packing density of 0.46 g / cm³. 3 The carbon black coverage of the PA12 powder surface is 30%.

[0037] Example 1

[0038] Step 1: Nylon 12 (PA12) powder is evenly spread onto the substrate using a roller. The powder layer thickness is 90 μm. The average particle size of the PA12 powder is 60 μm, the particle size spacing is 1.0, and the loose packing density is 0.45 g / cm³. 3 .

[0039] Step 2: Carbon black with a particle size of 15nm is sprayed onto the surface of PA12 powder through a nozzle, ensuring uniform dispersion. The spraying rate is 40mg / s, the nozzle movement speed is 200mm / s, and the width of the sprayed nanoparticles is 100mm. Then, a 1064nm fiber laser is used to scan the PA12 powder, heating it to 180℃ for 8 seconds until the powder surface melts. The fiber laser power is 500W, the scanning line spacing is 0.3mm, the scanning speed is 20m / s, and the spot size is 1000μm. The carbon black is embedded in the PA12 powder and adheres to its surface, making it difficult to detach.

[0040] Step 3: After the treatment in Step 2, cold nitrogen gas is introduced at a cooling rate of 8°C / s to cool the PA12 powder below its glass transition temperature, reaching a cooling temperature of 40°C. This is to stabilize the powder's overall shape and prevent deformation during subsequent scraping. This results in PA12 powder with carbon black evenly distributed, achieving a carbon black coverage of 150% on the PA12 powder surface. The powder is then scraped off the substrate using a scraper, yielding PA12 powder with carbon black adhering to it.

[0041] Step 4: The PA12 powder with carbon black adhering to it obtained in Step 3 is sieved through a 100-mesh sieve and then subjected to air classification to obtain PA12 powder for selective laser sintering. The PA12 powder for selective laser sintering has a particle size of 58 μm, a particle size distribution of 0.75, and a loose packing density of 0.52 g / cm³. 3 The carbon black coverage of the PA12 powder surface is 150%.

[0042] Example 2

[0043] Step 1: Apply polyurethane (TPU) powder evenly to the substrate using a roller. The powder layer thickness is 216 μm. The average particle size of the TPU powder is 180 μm, the particle size distribution is 1.3, and the bulk density is 0.85 g / cm³. 3 .

[0044] Step Two: 200nm copper nanoparticles are sprayed onto the TPU powder surface using a nozzle, ensuring uniform dispersion. The nozzle spray rate is 300mg / s, the nozzle movement speed is 150mm / s, and the width of the sprayed nanoparticles is 200mm. Then, a 1600nm fiber laser is used to scan the TPU powder, heating it to 90℃ for 20 seconds to induce a molten state on the powder surface. The fiber laser power is 800W, the scanning line spacing is 0.5mm, the scanning speed is 40m / s, and the spot size is 2000μm. The copper nanoparticles become embedded in the TPU powder and adhere to its surface, making them difficult to detach.

[0045] Step 3: After the treatment in Step 2, cold nitrogen gas is introduced at a cooling rate of 10℃ / s to cool the TPU powder below its glass transition temperature. The cooling temperature is 10℃ to fix its overall state and prevent deformation during subsequent scraping. This results in TPU powder with uniformly distributed copper nanoparticles, achieving 100% coverage of the TPU powder surface. The powder is then scraped off the substrate using a scraper, yielding TPU powder with adhered copper nanoparticles.

[0046] Step 4: The TPU powder with copper nanoparticles adhered to it obtained in Step 3 is sieved through a 20-mesh sieve and then subjected to air classification to obtain TPU powder for selective laser sintering. The TPU powder for selective laser sintering has a particle size of 165 μm, a particle size distribution of 1.1, and a bulk density of 0.9 g / cm³. 3 The copper nanoparticles cover 100% of the TPU powder surface.

[0047] Example 3

[0048] Step 1: Evenly spread polypropylene (PP) powder onto the substrate using a scraper. The powder layer thickness is 80 μm. The average particle size of the PP powder is 40 μm, the particle size distribution is 0.5 mm, and the bulk density is 0.20 g / cm³. 3 .

[0049] Step 2: 150nm nickel nanoparticles are sprayed onto the surface of PP powder using a nozzle, ensuring uniform dispersion. The nozzle spray rate is 10mg / s, the nozzle movement speed is 300mm / s, and the width of the sprayed nanoparticles is 200mm. Then, a 500nm fiber laser is used to scan the PP powder, heating it to 130℃ for 1s to induce a molten state on the powder surface. The fiber laser power is 30W, the scanning line spacing is 0.1mm, the scanning speed is 2m / s, and the spot size is 50μm. The nickel nanoparticles become embedded in the PP powder and adhere to its surface, making them difficult to detach.

[0050] Step 3: After the treatment in Step 2, cold nitrogen gas is introduced at a cooling rate of 10℃ / s to cool the PP powder below its glass transition temperature. The cooling temperature is 10℃ to fix its overall state and prevent deformation during subsequent scraping of the powder. This results in PP powder with uniformly distributed nickel nanoparticles, with a nickel nanoparticle coverage of 20% on the PP powder surface. The powder is then scraped off the substrate using a scraper, resulting in PP powder with adhered nickel nanoparticles.

[0051] Step 4: The PP powder with nickel nanoparticles adhering to it obtained in Step 3 is sieved through a 200-mesh sieve and then subjected to air classification to obtain PP powder for selective laser sintering. The PP powder for selective laser sintering has a particle size of 38 μm, a particle size distribution of 0.5 mm, and a loose packing density of 0.25 g / cm³. 3 The nickel nanoparticles cover 20% of the PP powder surface.

[0052] Example 4

[0053] Step 1: Spread polycarbonate (PC) powder evenly onto the substrate using a roller. The powder layer thickness is 180 μm. The average particle size of the PC powder is 120 μm, the particle size spacing is 1.6, and the bulk density is 0.75 g / cm³. 3 .

[0054] Step 2: Graphene with a particle size of 18 nm and carbon black with a particle size of 400 nm are sprayed onto the surface of PC powder through a nozzle, ensuring uniform dispersion of the graphene and carbon black. The nozzle spray rate is 200 mg / s, the nozzle movement speed is 200 mm / s, and the width of the sprayed nanoparticles is 100 mm. Then, a 1080 nm fiber laser is used to scan the PC powder, heating it to 220°C for 8 seconds to induce a molten state on the PC powder surface. The fiber laser power is 400 W, the scanning line spacing is 0.5 mm, the scanning speed is 25 m / s, and the spot size is 600 μm. The graphene and carbon black become embedded in the PC powder and adhere to its surface, making them difficult to detach.

[0055] Step 3: After the treatment in Step 2, cold nitrogen gas is introduced at a cooling rate of 8℃ / s to cool the PC powder below its glass transition temperature, reaching a cooling temperature of 40℃. This is to stabilize the overall state and prevent deformation during subsequent powder scraping. This results in PC powder with uniformly distributed graphene and carbon black, achieving a graphene and carbon black coverage of 240% on the PC powder surface. The powder is then scraped off the substrate using a scraper, yielding PC powder with adhered graphene and carbon black.

[0056] Step 4: The PC powder with graphene and carbon black adhering to it obtained in Step 3 is sieved through a 140-mesh sieve and then subjected to air classification to obtain PC powder for selective laser sintering. The PC powder for selective laser sintering has a particle size of 116 μm, a particle size distribution of 1.4, and a bulk density of 0.78 g / cm³. 3 The coverage of graphene and carbon black on the PC powder surface is 240%.

[0057] Example 5

[0058] Step 1: Polyphenylene sulfide (PPS) powder is evenly spread onto the substrate using a roller, with a powder layer thickness of 210 μm. The average particle size of the PPS powder is 140 μm, the particle size distribution is 1.4, and the loose packing density is 0.78 g / cm³. 3 .

[0059] Step 2: Carbon black with a particle size of 18nm is sprayed onto the surface of PPS powder through a nozzle, ensuring uniform dispersion. The nozzle spray rate is 100mg / s, the nozzle movement speed is 200mm / s, and the width of the sprayed nanoparticles is 100mm. Then, a 1064nm fiber laser is used to scan the PPS powder, heating it to 270℃ for 8 seconds to induce a molten state on the powder surface. The fiber laser power is 600W, the scanning line spacing is 0.8mm, the scanning speed is 35m / s, and the spot size is 1400μm. The carbon black is embedded in the PPS powder and adheres to its surface, making it difficult to detach.

[0060] Step 3: After the treatment in Step 2, cold nitrogen gas is introduced at a cooling rate of 8℃ / s to cool the PPS powder below its glass transition temperature, reaching a cooling temperature of 40℃. This is to stabilize the powder's overall shape and prevent deformation during subsequent scraping. This results in PPS powder with carbon black evenly distributed, achieving a carbon black coverage of 280% on the PPS powder surface. The powder is then scraped off the substrate using a scraper, yielding PPS powder with carbon black adhering to it.

[0061] Step 4: The PPS powder with carbon black adhering to it obtained in Step 3 is sieved through a 100-mesh sieve and then subjected to air classification to obtain PPS powder for selective laser sintering. The PPS powder for selective laser sintering has a particle size of 136 μm, a particle size distribution of 1.3, and a loose packing density of 0.82 g / cm³. 3 The carbon black coverage of the PPS powder surface is 280%.

[0062] Example 6

[0063] Step 1: Polyetheretherketone (PEEK) powder is evenly spread onto the substrate using a roller, with a powder layer thickness of 90 μm. The average particle size of the PEEK powder is 66 μm, the particle size distribution is 1.4, and the bulk density is 0.5 g / cm³. 3 .

[0064] Step 2: Carbon black with a particle size of 18nm is sprayed onto the surface of PEEK powder through a nozzle, ensuring uniform dispersion. The nozzle spray rate is 300mg / s, the nozzle movement speed is 200mm / s, and the width of the sprayed nanoparticles is 100mm. Then, a 1064nm fiber laser is used to scan the PEEK powder, heating it to 350℃ for 20s to induce a molten state on the surface. The fiber laser power is 240W, the scanning line spacing is 0.3mm, the scanning speed is 20m / s, and the spot size is 1000μm. The carbon black is embedded in the PEEK powder and adheres to its surface, making it difficult to detach.

[0065] Step 3: After the treatment in Step 2, cold nitrogen gas is introduced at a cooling rate of 10℃ / s to cool the PEEK powder below its glass transition temperature, reaching a cooling temperature of 40℃. This is to stabilize the powder's overall shape and prevent deformation during subsequent powder scraping. A uniformly distributed PEEK powder surface with carbon black is obtained, achieving a carbon black coverage of 500% on the PEEK powder surface. The powder is then scraped off the substrate using a scraper, resulting in PEEK powder with carbon black adhering to it.

[0066] Step 4: The PEEK powder with carbon black adhering to it obtained in Step 3 is sieved through a 100-mesh sieve and then subjected to air classification to obtain PEEK powder for selective laser sintering. The PEEK powder for selective laser sintering has a particle size of 62 μm, a particle size distribution of 1.2, and a loose packing density of 0.55 g / cm³. 3 The carbon black coverage of the PEEK powder surface is 500%.

[0067] The table below shows the properties of the polymer powders prepared in Comparative Example 1 and Examples 1-6:

[0068]

[0069] The polymer powders prepared in Comparative Example 1 and Example 1 were placed in a selective laser sintering apparatus for sintering, and the performance was compared repeatedly for the fifth time. The results are shown in Tables 1 and 2 below:

[0070]

[0071] Table 1: Comparison of New Fans

[0072]

[0073] Table 2: Performance Comparison After 5 Repetitions

[0074] As shown in Tables 1 and 2 above, the polymer powder prepared in Example 1 not only exhibits superior performance as fresh powder, but also maintains good performance after five repeated sintering cycles. In contrast, the polymer powder prepared in Comparative Example 1 shows poor performance as fresh powder, and its performance also declines significantly after five cycles.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for heat treatment of powders for selective laser sintering, characterized in that, Includes the following steps: Step 1: Evenly spread polymer powder on the substrate. The average particle size of the polymer powder is 40–180 μm, the particle size distribution is 0.5–2.0 μm, and the bulk density is 0.2–0.85 g / cm³. 3 ; Step 2: Nanoparticles are sprayed onto the surface of polymer powder using a nozzle. Then, a fiber laser with a wavelength of 500–1600 nm is used to scan the polymer powder, heating it to a molten state on the surface. The nanoparticles are then trapped into the polymer powder and adhere to its surface. The laser power of the fiber laser is 30–800 W, the scanning line spacing is 0.1–1.0 mm, the scanning speed is 2–40 m / s, and the spot size is 50–2000 μm. Step 3: After the treatment in Step 2, the polymer powder is cooled to below the glass transition temperature, and then the polymer powder is scraped off from the substrate to obtain polymer powder with adhered nanoparticles. Step 4: The polymer powder with adhered nanoparticles obtained in Step 3 is then subjected to sieving and air classification to obtain an average particle size of 38–165 μm, a particle size spacing of 0.5–1.9 μm, and a bulk density of 0.25–0.9 g / cm³. 3 Selective laser sintering of polymer powder, wherein the nanoparticles cover the surface of the polymer powder by 5% to 500%.

2. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, In step one, the polymer powder is evenly spread on the substrate using a roller or scraper.

3. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, In step one, the thickness of the polymer powder layer on the substrate is 1.0 to 2.0 times the average particle size of the polymer powder in step one.

4. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, In step two, the coverage rate of nanoparticles on the surface of polymer powder is 5-500%; in step two, the polymer powder is heated to 50-350℃ and heat-treated for 1-20 seconds.

5. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, The nozzle has a spray rate of 10–300 mg / s, a moving speed of 150–300 mm / s, and a powder width of 50–200 mm for the nanoparticles sprayed by the nozzle.

6. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, In step three, cold nitrogen gas is introduced to cool the polymer powder to below the glass transition temperature at a rate of 5–10 °C / s.

7. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, In step three, the polymer powder is scraped off the substrate using a scraper.

8. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, In step four, the polymer powder with adhered nanoparticles is sieved through a 20-200 mesh sieve.

9. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, The nanoparticles are one or more of metal nanoparticles and carbon nanoparticles; the particle size of the nanoparticles is 5-400 nm; the metal nanoparticles are gold nanoparticles, copper nanoparticles, silver nanoparticles, titanium nanoparticles, nickel nanoparticles or aluminum nanoparticles; the carbon nanoparticles are carbon black, carbon nanotubes or graphene.

10. The method for powder heat treatment for selective laser sintering according to claim 1, characterized in that, The polymer powder is polylactic acid, polyurethane, polyethylene, polypropylene, polystyrene, nylon, polycarbonate, polyphenylene sulfide, polybutylene terephthalate, or polyetheretherketone powder.

Images