Direct writing type 3D printing method based on path angle control

Abstract

The invention provides a direct-writing type 3D printing method based on path angle control. The direct-writing type 3D printing method is used for preparing a carbon fiber reinforced resin-based composite material component with high heat conductivity and excellent wear resistance. The method comprises the following steps that firstly, composite material ink is prepared, and the ink comprises bisphenol A epoxy resin, a TETA curing agent, short carbon fibers, hexagonal boron nitride nanosheets and a dispersing agent; secondly, a path structure is designed, a multi-layer spiral staggered path is adopted, the interlayer included angle of the path is controlled to range from 15 degrees to 45 degrees, G-codes are generated through a Python script, and it is ensured that the path is aligned with the heat flow direction; then, direct writing type printing equipment controlled by air pressure is used for printing, and printing parameters include the inner diameter of a nozzle being 0.6 mm, the printing pressure being 105 MPa, the printing speed being 10 mm / s and the printing layer height being 6 mm; and finally, after printing is completed, a sample piece is subjected to curing treatment at the temperature of 80 DEG C. By controlling the path angle, the directional arrangement of the carbon fibers in the composite material is optimized, the thermal conductivity and wear resistance of the composite material are improved, the anisotropic performance is good, and the performance can be regulated and controlled according to different application scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing, composite materials and functional structure design, in particular to a direct writing type 3D printing method for preparing a carbon fiber reinforced resin matrix composite material component with high thermal conductivity and excellent wear resistance, especially a structure construction technology with internal performance regulation realized by path angle programming. BACKGROUND

[0002] Carbon fiber reinforced composites are widely used in aerospace, electronic packaging, high-speed transportation equipment and high-end friction components due to their excellent specific strength, specific modulus and thermal physical properties. Direct ink writing (DIW) is an ideal technology for printing composite materials due to its friendliness to high viscosity fluids and flexibility in spatial path control. However, the current DIW process still has deficiencies in fiber arrangement control, interface fusion and structure-performance synergy, which limits its further application in directional thermal conduction and wear-resistant structures. For example, CN119635789A discloses a 3D printing device and method for carbon fiber toughened ceramic matrix composite material, which focuses more on the overall reinforcement of continuous carbon fiber bundles in ceramic matrix composites, and relies on mechanical devices to control fiber tension. It lacks strategies for directional arrangement of chopped carbon fibers in the matrix, and does not establish a mechanism for regulating the path angle design and thermal conductivity / friction performance. CN119159811B discloses a 3D printing system and printing control method based on printing path boundary distance and path direction angle, which divides the boundary sub-path and internal sub-path and adjusts the printing speed to improve the printing precision and efficiency. The core of this technology is the dynamic planning and optimization of path speed, mainly focusing on the motion control problem in the printing process. However, this method does not involve the structural configuration regulation of the printing material, especially does not consider the influence of path angle design on the directional arrangement of fibers, interface fusion and thermal conductivity / wear resistance in reinforced materials (such as chopped carbon fiber composite systems). Therefore, it is difficult to meet the performance optimization requirements of functional composites in terms of thermal conductivity and wear resistance.

[0003] The main problems include: lack of effective control of printing path direction on the orientation of reinforcing materials, leading to unclear performance anisotropy; weak interlayer bonding affecting the overall structural stability; lack of path and structure function performance coupling design strategy. Compared with the prior art, the present application realizes the ordered arrangement of chopped carbon fibers in the printing path by introducing a path angle control strategy, and further establishes a mapping mechanism between the path angle and the performance parameters (such as thermal conductivity and friction coefficient), thereby solving the decoupling problem of "path-structure-performance" in the existing DIW technology, and significantly improving the functional integration capability of the composite material and the performance controllability of the printed structure. SUMMARY

[0004] To overcome the above problems, the present application proposes a direct writing 3D printing process based on path angle controllable design, combined with modified chopped carbon fiber reinforced epoxy resin composite ink, to build a function structure with significant anisotropy, stable interface and customized performance.

[0005] The present application comprises the following steps:

[0006] Composite ink preparation: preferably, the matrix material is bisphenol A type epoxy resin, and the curing agent is TETA type aliphatic amine, with a mass ratio of 5:1 to 10:1. Preferably, the reinforcing filler is chopped carbon fiber, with a length of 100-200 μm and a mass fraction of 15-20 wt.%.

[0007] Preferably, the heat-conducting additive is hexagonal boron nitride nanosheet, with an addition amount of 2-5 wt.%; the dispersing agent is a polyether surfactant. After 30 minutes of mechanical stirring and 10 minutes of planetary stirring defoaming treatment, the composite ink with good rheological property is obtained.

[0008] Path structure design: preferably, a multi-layer spiral staggered path structure is adopted, with an interlayer included angle ranging from 15° to 45°; the path is generated into G-code through a self-defined Python script, realizing path alignment design consistent with the heat flow direction; the preferred path overlap rate is 20%-30%, to enhance the interlayer continuity and structural density.

[0009] Printing process control: preferably, a DIW printing device is used for pressure control, with an inner diameter of 0.6 mm, a printing pressure of 105 MPa, and a speed of 10 mm / s; the preferred layer height is 6 mm, the printing interval is controlled within the range of 200-260 μm, and the printing platform heating temperature is preferably 40°C; preferably, the sample is naturally cooled for 1 min after printing each layer; after printing is completed, the sample is cured at 80°C for 4-6 h.

[0010] Beneficial effects: Compared with the prior art, the present application realizes significant performance improvement in the 3D printing of carbon fiber reinforced composite materials through path angle controllable design and interface strengthening means. After adopting the preferred 15° path angle structure, the thermal conductivity of the sample in the heat conduction direction is increased to 9.425 W / m·K, which is nearly three times that of the pure resin matrix, showing good anisotropic thermal conductivity characteristics; at the same time, the friction coefficient is reduced, showing excellent wear resistance stability. By setting the printing layer cooling interval and platform heating strategy, the interfacial bonding quality of multiple layers is effectively improved, and the shear strength is increased. In addition, the printing process supports programmable control of path parameters, and can design performance differentiated areas according to different application scenarios, realizing the integration of thermal management and structural enhancement. The ink system has reasonable proportioning, good rheological property and forming stability, and the overall process has strong adaptability, which has great potential for large-scale popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a path angle arrangement structure diagram (15° / 25° / 35° / 45°).

[0012] Figure 2 is a printing piece cross-section SEM image (showing carbon fiber orientation).

[0013] Figure 3 is a comparison column chart of thermal conductivity and wear rate under different path angles. DETAILED DESCRIPTION

[0014] The technical solutions of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the present application, rather than all the embodiments. Based on the embodiments in the present application, other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0015] Example 1

[0016] 70 g of epoxy resin, 10 g of TETA curing agent, 20 g of chopped carbon fiber, 2 g of BN and 1 g of dispersant were mixed, stirred for 30 min and defoamed for 10 min to prepare an ink; the above-mentioned ink was used to print a sample with a size of 20 mm×20 mm×6 mm, the path angle was set to 15° spiral structure, and other parameters were: nozzle inner diameter 0.6 mm, pressure 105 MPa, speed 10 mm / s, layer height 6 mm, platform temperature 40°C; after printing, it was cured at 60°C for 6 hours. Finally, the tribological properties and thermal conductivity of the sample were tested in the direction by using a ball-on-disc friction tester and a thermal conductivity tester.

[0017] Through experimental determination, the thermal conductivity of the spiral structure with a path angle of 15° is 9.425 W / m·K, and the wear rate is 2.9×10 -5 mm 3 / Nm.

[0018] Comparative example

[0019] To analyze the influence of the path angle, the performance of samples with three angles (25°, 35° and 45°) is compared, and other parameters remain unchanged. The thermal conductivity and wear rate test results are as follows: Interlayer included angle Thermal conductivity λ (W / m·K) Wear rate (10 -5 mm 3 / (Nm)) 15° 9.425 2.9 25° 7.205 5.7 35° 5.183 7.5 45° 4.653 7.9

[0020] The results show that as the interlayer path angle increases, the thermal conductivity of the composite material in the heat conduction direction decreases significantly. The sample with an angle of 15° shows the highest thermal conductivity, indicating that a smaller angle helps to build a continuous and parallel high-efficiency heat conduction path in the direction of heat flow. This structure is conducive to the formation of a nearly linear arrangement of chopped carbon fibers between the layers, which maximizes the reduction of interfacial thermal resistance. As the path angle increases, the wear rate gradually increases, indicating that the greater the path bending degree, the rougher the surface microstructure, and the poorer the interface stability. The path programming method provided by the present application has the advantages of flexibility, controllability and significant performance difference, and can provide a basis for the customized design of multifunctional composite material structures.

[0021] Although the above embodiments have been described in detail, they are only part of the embodiments of the present application, not all embodiments. Skilled persons can derive other embodiments from these embodiments without creative labor, and these embodiments all belong to the protection scope of the present application.

Claims

1. A direct writing 3D printing method based on path angle control, characterized in that: The following steps are involved: (1) Preparation of composite ink: Bisphenol A epoxy resin is used as the matrix, TETA curing agent, short carbon fiber (length 100-200 μm), thermal conductive additive hexagonal boron nitride (BN) and dispersant are added, mixed and stirred and degassed to obtain printable ink; (2) Path structure design: Use the spiral staggered mode to set the interlayer path angle to 15°~45°, and control the fiber arrangement direction through G-code path programming; (3) Printing process control: Printing was performed in a pneumatic direct-write 3D printing device with a nozzle inner diameter of 0.6 mm, a printing pressure of 105 MPa, a printing speed of 10 mm / s, a layer height of 6 mm, a printing platform heating temperature of 40°C, and a pause of 1 min for natural cooling after each layer was printed. (4) Curing treatment: After printing is completed, the printed sample is placed in a 60-80°C environment for thermal curing for 4-6 hours to obtain the final composite structure.

2. The method according to claim 1, wherein the amount of BN added is 2-5 wt.% to enhance the thermal conductivity of the composite material.

3. The method according to claim 1, wherein the printing path is generated by a Python script, which supports programmatic control of path direction, overlap rate (preferably 20% to 30%) and regional difference performance.

4. The method according to claim 1, wherein the preferred path angle is 15° to obtain the highest thermal conductivity and the lowest wear rate.

5. The method according to claim 1, wherein the printing process can strengthen the interlayer bonding force by intermittently combining platform heating and interlayer cooling.

6. The method according to claim 1, wherein a ball-on-disc friction tester and a thermal conductivity tester are used to perform directional tests on the tribological properties and thermal conductivity of the sample.

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