Surface cold sintering process for SLS nylon parts

Abstract

The application discloses a kind of SLS nylon workpiece surface cold sintering process method, with SLS nylon workpiece, potassium tert-butoxide, dicyclohexyl-18-crown-6, 3-(2,3-epoxy propoxy) propyl trimethoxysilane, 10% solute mass fraction formic acid aqueous solution, argon, tetrahydrofuran as raw material, with built-in atomization granularity 3 μm-5 μm atomization device, low-temperature pulse plasma generating device, heating device, three-dimensional gas stirring device of protective atmosphere resistance furnace as production equipment, experiences surface hydroxylation, surface plasma activation, cold sintering three steps.SLS nylon workpiece treated by the application has the characteristics of high elongation at break, good surface integrity, high notched impact strength and good surface roughness.

Description

Technical Field

[0001] This invention relates to a selective laser printing process, and more particularly to a cold sintering process for SLS nylon parts. Background Technology

[0002] 3D printing is a layer-by-layer manufacturing technology. Defects such as shrinkage cavities, inclusions, and cracks are easily generated between the layers, resulting in problems such as poor interlayer air tightness, poor water tightness, and low fracture toughness of 3D printed parts. The strong anisotropy limits the engineering application of 3D printing technology.

[0003] Therefore, there is a current need for a surface cold sintering process for SLS nylon parts that has high elongation at break, good surface integrity, high unnotched impact strength, and good surface roughness. Summary of the Invention

[0004] This invention aims to provide a surface cold sintering process for SLS nylon parts that exhibits high elongation at break, good surface integrity, high unnotched impact strength, and good surface roughness.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a cold sintering process for the surface of SLS nylon parts, comprising the following stages:

[0006] S1: Raw Material Preparation

[0007] ① Raw material preparation: Prepare SLS nylon parts, sufficient potassium tert-butoxide, sufficient dicyclohexyl-18-crown ether-6, sufficient 3-(2,3-epoxypropoxy)propyltrimethoxysilane, sufficient 10% formic acid aqueous solution, sufficient argon gas, and sufficient tetrahydrofuran.

[0008] ② Equipment preparation: Prepare a protective atmosphere resistance furnace with a built-in atomizing device with a particle size of 3μm-5μm, a low-temperature pulsed plasma generator, a heating device, and a three-dimensional gas stirring device;

[0009] S2: Surface activation of the workpiece

[0010] ① Place the SLS nylon part prepared in step ① of stage S1 into the protective atmosphere resistance furnace prepared in step ② of stage S1, and introduce argon gas for protection.

[0011] ②Mix the potassium tert-butoxide, dicyclohexyl-18-crown-6 and tetrahydrofuran prepared in step ① of stage S1 in a ratio of (28-32) : 1 : (3500-3800) by mass, uniformly, to form a mixed solution, then atomize the mixed solution into the reaction area where the SLS nylon part is located, and start the three-dimensional gas stirring device, and maintain for 70-80 min; then heat to 45-55 DEG C, then add 3wt%-3.5wt% of 3-(2,3-epoxypropoxy) propyl trimethoxysilane prepared in step ① of stage S1 into the mixed solution according to the total mass of the mixed solution, and continue to maintain the temperature and the three-dimensional gas stirring, for 120-150 min, then vacuumize, then atomize the tetrahydrofuran prepared in step ① of stage S1 to flush the surface of the part, to obtain the surface-hydroxylated part;

[0012] ③Vacuumize the area where the surface-hydroxylated part obtained in step ② is located again, then fill with sufficient argon, and use the low-temperature pulse plasma generating device to perform plasma treatment on the part as a target with the process parameters of 55-60 V and 1.7-1.8 A, to obtain the surface-activated part.

[0013] S3: Low-temperature sintering

[0014] ① Atomize the formic acid aqueous solution prepared in step ① of stage S1 into the reaction area where the surface-activated part obtained in step ③ of stage S2 is located, start the three-dimensional gas stirring device, heat to 45-55 DEG C, and treat for 50-60 min, to obtain the required surface-low-temperature-sintered part.

[0015] Compared with the prior art, the application has the following advantages due to the above technical scheme:

[0016] (1) The application aims at the bottleneck problem of the polymer 3D printing technology, and the nylon 12 SLS part is taken as the research object in the actual measurement, the key technology of cold sintering of the polymer SLS part is researched, and the cold sintering technology is innovatively applied to the polymer 3D printing, so that the comprehensive performance of the polymer 3D printing part is greatly improved, and the application and development of the polymer 3D printing technology are promoted. Since the principle of the application is a general chemical principle for polyamides, it should be applicable to all nylon materials.

[0017] (2) According to the actual measurement, after the SLS part prepared by using nylon 12 as the raw material and adopting the application, the elongation at break is increased from 2% to more than 10%, the unnotched impact strength is increased from 3 KJ / m2 to 6 KJ / m2, and the surface roughness is reduced from 14 μm to less than 7 μm.

[0018] (3) This invention improves the problems of low elongation at break, low impact strength at notches, and high surface roughness of SLS parts from the perspective of improving surface integrity and reducing notch sensitivity. It develops a new type of post-processing technology for selective laser printing. Compared with conventional parts, the parts processed by this invention have better comprehensive mechanical properties.

[0019] (4) In a macroscopic comparison and analysis of the parts made by the present invention and conventional technology, it was found that the surface of the parts treated by the method described in the present invention is smoother and the parts aged and yellowed later after being placed in the same environment for a longer period of time compared with commercially available powder.

[0020] (5) The present invention utilizes the edge preferential corrosion effect similar to electrochemical polishing to achieve atomized gas plasma chemical polishing on the surface of the part, which significantly reduces the surface roughness of the part and improves the surface integrity of the part.

[0021] Therefore, the present invention has the characteristics of high elongation at break, good surface integrity, high unnotched impact strength, and good surface roughness. Implementation

[0022] Example

[0023] A surface cold sintering process for SLS nylon parts includes the following stages:

[0024] S1: Raw Material Preparation

[0025] ① Raw material preparation: Prepare SLS nylon parts, sufficient potassium tert-butoxide, sufficient dicyclohexyl-18-crown ether-6, sufficient 3-(2,3-epoxypropoxy)propyltrimethoxysilane, sufficient 10% formic acid aqueous solution, sufficient argon gas, and sufficient tetrahydrofuran.

[0026] ② Equipment preparation: Prepare a protective atmosphere resistance furnace with a built-in atomizing device with a particle size of 3μm-5μm, a low-temperature pulsed plasma generator, a heating device, and a three-dimensional gas stirring device;

[0027] S2: Surface activation of the workpiece

[0028] ① Place the SLS nylon part prepared in step ① of stage S1 into the protective atmosphere resistance furnace prepared in step ② of stage S1, and introduce argon gas for protection.

[0029] ② Mix potassium tert-butoxide, dicyclohexyl-18-crown ether-6, and tetrahydrofuran prepared in step ① of stage S1 at a mass ratio of (28-32):1:(3500-3800) to form a mixture. Then, atomize the mixture and pass it into the reaction area where the SLS nylon part is located. Turn on the three-dimensional gas stirring device and maintain it for 70-80 minutes. Raise the temperature to 45℃-55℃, and then add 3wt%-3.5wt% of 3-(2,3-epoxypropoxy)propyltrimethoxysilane prepared in step ① of stage S1 to the mixture. Continue to maintain the temperature and three-dimensional gas stirring for 120-150 minutes. Then, evacuate the vacuum and use the atomized tetrahydrofuran prepared in step ① of stage S1 to brush the surface of the part to obtain the surface hydroxylated part.

[0030] ③ After step ②, the area where the surface hydroxylated part is located is evacuated again and then filled with sufficient argon gas. A low-temperature pulsed plasma generator is used to perform plasma treatment on the part with process parameters of 55V-60V and 1.7A-1.8A to obtain a surface-activated part.

[0031] S3: Low-temperature sintering

[0032] ① The formic acid aqueous solution prepared in step S1 ① is atomized and introduced into the reaction area where the surface-activated part obtained in step S2 ③ is located. The three-dimensional gas stirring device is turned on, the temperature is raised to 45℃-55℃, and the treatment is carried out for 50min-60min to obtain the desired surface low-temperature sintered part.

[0033] The SLS-printed nylon 12 parts manufactured according to the method of this embodiment have increased the elongation at break from 2% to over 10%, the unnotched impact strength from 3KJ / m2 to 6KJ / m2, and the surface roughness from 14μm to below 7μm.

[0034] The above description of the disclosed embodiments is merely intended to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for cold sintering the surface of SLS nylon parts, characterized in that... Includes the following stages: S1: Raw Material Preparation ① Raw material preparation: Prepare SLS nylon parts, sufficient potassium tert-butoxide, sufficient dicyclohexyl-18-crown ether-6, sufficient 3-(2,3-epoxypropoxy)propyltrimethoxysilane, sufficient 10% formic acid aqueous solution, sufficient argon gas, and sufficient tetrahydrofuran. ② Equipment preparation: Prepare a protective atmosphere resistance furnace with a built-in atomizing device with a particle size of 3μm-5μm, a low-temperature pulsed plasma generator, a heating device, and a three-dimensional gas stirring device; S2: Surface activation of the workpiece ① Place the SLS nylon part prepared in step ① of stage S1 into the protective atmosphere resistance furnace prepared in step ② of stage S1, and introduce argon gas for protection. ② Mix potassium tert-butoxide, dicyclohexyl-18-crown ether-6, and tetrahydrofuran prepared in step ① of stage S1 at a mass ratio of (28-32):1:(3500-3800) to form a mixture. Then, atomize the mixture and pass it into the reaction area where the SLS nylon part is located. Turn on the three-dimensional gas stirring device and maintain it for 70-80 minutes. Raise the temperature to 45℃-55℃, and then add 3wt%-3.5wt% of 3-(2,3-epoxypropoxy)propyltrimethoxysilane prepared in step ① of stage S1 to the mixture. Continue to maintain the temperature and three-dimensional gas stirring for 120-150 minutes. Then, evacuate the vacuum and use the atomized tetrahydrofuran prepared in step ① of stage S1 to brush the surface of the part to obtain the surface hydroxylated part. ③ After step ②, the area where the surface hydroxylated part is located is evacuated again and then filled with sufficient argon gas. A low-temperature pulsed plasma generator is used to perform plasma treatment on the part with process parameters of 55V-60V and 1.7A-1.8A to obtain a surface-activated part. S3: Low-temperature sintering ① The formic acid aqueous solution prepared in step S1 ① is atomized and introduced into the reaction area where the surface-activated part obtained in step S2 ③ is located. The three-dimensional gas stirring device is turned on, the temperature is raised to 45℃-55℃, and the treatment is carried out for 50min-60min to obtain the desired surface low-temperature sintered part.