A winding forming method of an ultra-thin carbon-carbon screen blank

Abstract

This invention discloses a method for winding an ultrathin carbon-carbon screen preform, comprising: selecting a fiber reinforcement material that meets the minimum multifilament strength requirement and a resin matrix material that meets the residual carbon rate requirement; formulating a winding regime; obtaining a fiber-reinforced resin matrix composite material based on the fiber reinforcement material and the resin matrix material; and curing and machining the fiber-reinforced resin matrix composite material according to the winding regime to obtain the ultrathin carbon-carbon screen preform. This invention can prepare ultrathin carbon-carbon screen preforms that meet the required specifications and have reliable quality.

Description

Technical Field

[0001] This invention belongs to the technical field of ultra-thin carbon screen blanks, and particularly relates to a winding molding method for ultra-thin carbon screen blanks. Background Technology

[0002] The level of spacecraft manufacturing is an important reference for measuring a country's comprehensive national strength. With the gradual advancement of major space projects such as deep space exploration in my country, higher requirements have been placed on the lifespan, reliability, and other indicators of new-generation spacecraft such as deep space probes and high-capacity satellites. Traditional chemical propulsion systems are increasingly unable to meet the needs of deep space exploration missions.

[0003] To address the new challenges of deep space exploration, long-life electric propulsion ion engines have become the preferred propulsion system for next-generation spacecraft. The working principle of an electric propulsion ion engine involves first ionizing the propellant using electrical energy. The ionized ions are then accelerated and extracted as they pass through a grid assembly with an ultra-thin screen structure, thereby generating long-lasting stable thrust. The grid assembly is the core component of the electric propulsion ion engine, and its design and manufacturing level directly determines the performance and lifespan of the propulsion system.

[0004] Currently, my country has made breakthroughs in the key technologies for manufacturing conventional molybdenum metal gates, but their lifespan is only 14,000 hours, which is still far from the 4,000-hour lifespan requirement for deep space exploration. To improve the structural performance of ultra-thin screen structure gate components, further research on the application of advanced materials is necessary. Carbon-carbon composite materials are an ideal alternative to molybdenum metal as a material for gate components in electric propulsion ion engines. However, there are technical barriers in winding carbon-carbon composite materials into ultra-thin carbon-carbon screen blanks, and the ultra-thin carbon-carbon screen blanks are prone to fractures throughout their thickness due to thickness limitations. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a winding molding method for ultra-thin carbon-carbon screen blanks, which can prepare ultra-thin carbon-carbon screen blanks that meet the index requirements and have reliable quality.

[0006] The objective of this invention is achieved through the following technical solution: a method for winding an ultrathin carbon-carbon screen blank, comprising: selecting a fiber reinforcement material that meets the minimum multifilament strength and a resin matrix material that meets the residual carbon rate index; formulating a winding regime; obtaining a fiber-reinforced resin matrix composite material based on the fiber reinforcement material and the resin matrix material; and curing and machining the fiber-reinforced resin matrix composite material according to the winding regime to obtain an ultrathin carbon-carbon screen blank.

[0007] In the above-mentioned winding molding method for ultrathin carbon-carbon screen blanks, the minimum multifilament strength of the fiber reinforcement material is obtained by the following formula:

[0008]

[0009] Where σ is the minimum multifilament strength of the fiber reinforcement material, k1 is the first coefficient, w is the porosity, m is the maximum allowable weight of the ultrathin carbon screen blank, g is the standard gravitational acceleration, d is the outer diameter of the ultrathin carbon screen blank, and h is the thickness of the ultrathin carbon screen blank.

[0010] In the above-mentioned winding molding method for ultra-thin carbon screen blanks, the residual carbon content of the resin matrix material is ≥55%.

[0011] In the above-mentioned method for winding ultrathin carbon screen blanks, the winding system includes: the number of winding layers, the winding sequence, and the winding tape spacing.

[0012] In the above-mentioned method for winding ultrathin carbon screen blanks, the number of winding layers is 6.

[0013] In the above-mentioned winding molding method for ultra-thin carbon carbon screen blanks, the winding sequence is 0°, 60°, 120°, 60°, 120°, 0°.

[0014] In the above-mentioned method for winding ultrathin carbon-carbon screen blanks, the winding distance is obtained by the following formula:

[0015]

[0016] Where b is the winding distance, k2 is the second coefficient, m is the maximum allowable weight of the ultrathin carbon screen blank, l is the unfolding bandwidth of the fiber reinforcement material during winding, t is the linear density value of the fiber reinforcement material, d is the outer diameter value of the ultrathin carbon screen blank, and n is the number of winding layers.

[0017] In the above-mentioned method for winding ultrathin carbon-carbon screen blanks, the process of curing and machining the fiber-reinforced resin-based composite material according to the winding regime to obtain the ultrathin carbon-carbon screen blank includes: winding the fiber-reinforced resin-based composite material onto a mold fixture according to the winding regime; placing the fiber-reinforced resin-based composite material and the mold fixture together into a curing device and curing it according to the curing regime; after curing is completed and the material is allowed to cool naturally, removing the fiber-reinforced resin-based composite material and the mold fixture together; and machining it according to the preset shape and size of the ultrathin carbon-carbon screen blank to obtain the ultrathin carbon-carbon screen blank.

[0018] In the above-mentioned method for winding and forming ultra-thin carbon-carbon screen blanks, the mold fixture is a hexagonal winding fixture; wherein, the six corners of the hexagonal winding fixture are respectively machined with a first tightening hole, a second tightening hole, a third tightening hole, a first fixing screw hole, a second fixing screw hole and a third fixing screw hole.

[0019] In the above-mentioned method for winding and forming ultra-thin carbon screen blanks, the curing process is as follows: after holding at 60°C for 3 hours, the temperature is raised to 105°C; after holding at 105°C for 4 hours, the temperature is raised to 135°C; after holding at 135°C for 4 hours, the temperature is raised to 165°C; and after holding at 165°C for 3 hours, the temperature is naturally cooled to room temperature.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The present invention uses a specific empirical formula to calculate the minimum multifilament strength index required for the reinforcing fiber material, thereby ensuring that the ultra-thin carbon screen blank is not prone to breakage during subsequent processing.

[0022] (2) This invention identifies a reliable matrix material that ensures that the ultrathin carbon screen has a high (≥55%) residual carbon rate after undergoing the carbonization process;

[0023] (3) The present invention uses a specific empirical formula to calculate the winding distance of the reinforcing fiber material, thereby ensuring that the finished blank meets the thickness index requirements;

[0024] (4) The present invention can prepare ultra-thin carbon screen blanks that meet the index requirements and have reliable quality. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0026] Figure 1 This is a schematic diagram of the winding fixture for the ultra-thin carbon screen blank provided in an embodiment of the present invention;

[0027] Figure 2 yes Figure 1 Schematic diagram of section AA. Detailed Implementation

[0028] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] The process of preparing ultrathin carbon-carbon screen grids can be roughly divided into three major steps: blank forming, carbonization, and finishing. Among them, blank forming is the first and most critical process, which determines the difficulty of subsequent processes and the forming effect of the final product.

[0030] This embodiment is designed as follows: Figure 1 The ultra-thin carbon screen blank shown can be obtained by using the fiber winding tool after completing the material selection and winding system design work through fiber winding and subsequent pressure curing. The fiber orientation and material thickness meet the design requirements.

[0031] Due to thickness limitations, ultra-thin carbon-carbon screen blanks are prone to fractures that extend through the thickness direction. Therefore, the rigidity of the finished product should be ensured by establishing selection criteria for the reinforcing fiber material of the blank. During the preparation of ultra-thin carbon-carbon screen blanks, preparations must be made for the next carbonization process to ensure that the blank still has a high residual carbon rate after the carbonization process. The thickness of ultra-thin carbon-carbon screen blanks has strict requirements, and the winding system of ultra-thin carbon-carbon screen blanks should be reasonably formulated according to its thickness conditions.

[0032] This embodiment provides a method for winding an ultrathin carbon-carbon screen blank. The method includes: selecting a fiber reinforcement material that meets the minimum multifilament strength and a resin matrix material that meets the residual carbon rate index; formulating a winding regime; obtaining a fiber-reinforced resin matrix composite material based on the fiber reinforcement material and the resin matrix material; and curing and machining the fiber-reinforced resin matrix composite material according to the winding regime to obtain an ultrathin carbon-carbon screen blank.

[0033] The minimum multifilament strength of fiber-reinforced materials is obtained by the following formula:

[0034]

[0035] Where σ is the minimum multifilament strength of the fiber reinforcement material, k1 is the first coefficient, w is the porosity, m is the maximum allowable weight of the ultrathin carbon screen blank, g is the standard gravitational acceleration, d is the outer diameter of the ultrathin carbon screen blank, and h is the thickness of the ultrathin carbon screen blank.

[0036] The residual carbon content of the resin matrix material is ≥55%.

[0037] The winding process includes: the number of winding layers, the winding sequence, and the winding tape spacing. The number of winding layers is 6. The winding sequence is 0°, 60°, 120°, 60°, 120°, 0°.

[0038] The winding distance is obtained by the following formula:

[0039]

[0040] Where b is the winding distance, k2 is the second coefficient, m is the maximum allowable weight of the ultrathin carbon screen blank, l is the unfolding bandwidth of the fiber reinforcement material during winding, t is the linear density value of the fiber reinforcement material, d is the outer diameter value of the ultrathin carbon screen blank, and n is the number of winding layers.

[0041] The process of curing and machining fiber-reinforced resin-based composite materials according to a winding system to obtain an ultra-thin carbon-carbon screen blank includes: winding the fiber-reinforced resin-based composite material onto a mold according to a winding system; placing the fiber-reinforced resin-based composite material and the mold together into a curing device and curing it according to a curing system; after curing is completed and the material is allowed to cool naturally, removing the fiber-reinforced resin-based composite material and the mold together; and machining it according to the preset shape and size of the ultra-thin carbon-carbon screen blank to obtain the ultra-thin carbon-carbon screen blank.

[0042] like Figure 1 and Figure 2 As shown, the mold fixture is a hexagonal winding fixture; wherein, the six corners of the hexagonal winding fixture are respectively machined with a first tightening hole 1, a second tightening hole 2, a third tightening hole 3, a first fixing screw hole 4, a second fixing screw hole 5, and a third fixing screw hole 6. By switching different fixing screw holes and corresponding tightening holes to fix the winding fixture, composite material layer winding in different winding directions can be completed.

[0043] The curing process involves maintaining a temperature of 60°C for 3 hours, then raising the temperature to 105°C, maintaining a temperature of 105°C for 4 hours, then raising the temperature to 135°C, maintaining a temperature of 135°C for 4 hours, then raising the temperature to 165°C, maintaining a temperature of 165°C for 3 hours, and finally allowing the temperature to cool naturally to room temperature.

[0044] The fabrication and molding of ultra-thin carbon fiber screen blanks requires the use of winding fixtures. Taking ultra-thin carbon fiber screen blanks with single-layer fiber winding angles of 0°, 60°, and 120° as an example, the designed hexagonal winding fixture is as follows: Figure 1 As shown. From Figure 2 As can be seen, the six corners of the hexagonal winding fixture are respectively machined with a first tightening hole 1, a second tightening hole 2, a third tightening hole 3, a first fixing screw hole 4, a second fixing screw hole 5, and a third fixing screw hole 6. By switching different fixing screw holes and corresponding tightening holes of the winding fixture for fixation, composite material layer winding in different winding directions can be completed.

[0045] The preparation process of ultrathin carbon fiber screen preforms includes the following steps:

[0046] (1) Selection of fiber reinforcement materials and resin matrix materials;

[0047] (2) The formulation of the entanglement system;

[0048] (3) Curing and mechanical processing.

[0049] The specific implementation method is as follows:

[0050] (1) Selection of fiber reinforcement materials and resin matrix materials

[0051] a) Based on the required screen thickness, open area ratio, and outer diameter, the minimum multifilament strength of the required fiber reinforcement material can be calculated using the following empirical formula:

[0052]

[0053] In the formula, σ is the minimum multifilament strength value of the fiber reinforcement material; k1 is an empirical parameter, generally taken as 5 to 8; w is the porosity, that is, the ratio of the open area to the area of ​​the open region (the sum of the open area and the area of ​​the gap between open areas); m is the maximum allowable weight of the ultra-thin carbon screen blank; g is the standard gravitational acceleration; d is the outer diameter of the ultra-thin carbon screen blank; and h is the thickness of the ultra-thin carbon screen blank.

[0054] Based on the minimum multifilament strength value calculated according to formula (1), it is sufficient to select fibers whose average multifilament strength test value is higher than this value. It is recommended to select fiber reinforcement materials from carbon fibers.

[0055] b) Process verification shows that using phenolic resin as the matrix material for ultra-thin carbon screen blanks can ensure that the blanks have a high (≥55%) carbon residue rate (i.e., the mass percentage of carbon element in the matrix material residue after the carbonization process) after subsequent carbonization. Other resins that can meet the carbon residue rate index can also be used as matrix materials.

[0056] (2) Formulation of the entanglement system

[0057] c) Taking an ultra-thin carbon-carbon screen blank with single-layer fiber winding angles of 0°, 60°, and 120° as an example, the winding regime is designed. First, the number of winding layers needs to be determined. It is recommended that the number of winding cycles be no less than 2. In the case selected in this invention, since the ultra-thin carbon-carbon screen blank is designed with three winding angles of 0°, 60°, and 120°, it is recommended to set the number of winding layers to 6.

[0058] d) Regarding the design of the winding sequence for each winding layer, it is not recommended to wind layers in the same direction together. Therefore, the winding sequence is set to 0°, 60°, 120°, 60°, 120°, 0°.

[0059] e) Based on parameters such as the thickness of the finished preform, the spread width of the reinforcing fiber material, the width of the winding coverage area, and the adhesive content of the composite material, the winding distance of the reinforcing fiber material can be calculated using the following empirical formula:

[0060]

[0061] In the formula, b is the winding distance of the fiber reinforcement material; k2 is an empirical parameter, generally taken as 0.75 to 0.95; m is the maximum allowable weight of the ultra-thin carbon screen blank; l is the unfolding bandwidth of the fiber reinforcement material during the winding process; t is the linear density value of the fiber reinforcement material; d is the outer diameter value of the ultra-thin carbon screen blank; and n is the number of winding layers.

[0062] (3) Curing and machining

[0063] f) After the fiber-reinforced resin-based composite material is wound, the wound composite material along with the mold tooling can be placed into the curing equipment and cured according to the curing regime of the selected resin material;

[0064] g) After curing and allowing natural cooling, remove the composite material along with the mold fixture and send it for machining to the shape and dimensions of the ultra-thin carbon screen blank. It is recommended to select the overlapping areas of each winding layer for machining and remove the edge composite material.

[0065] Based on the strength value calculated using the empirical formula for the minimum multifilament strength of the required fiber reinforcement material, a certain grade of domestically produced T1000 carbon fiber was selected as the fiber reinforcement material. The selected resin was a certain grade of phenolic resin. The designed ultrathin carbon-carbon screen preform composite material had 6 winding layers and a thickness of 0.75 mm. Based on the winding angles of different winding layers, the designed winding sequence was 0°, 60°, 120°, 60°, 120°, 0°. Based on the empirical formula for the winding distance of the reinforcement fiber material, the winding distance was calculated to be 0.65 mm. According to the relevant process parameters of the selected resin, the determined curing regime was 60℃ / 3h → 105℃ / 4h → 135℃ / 4h → 165℃ / 3h → natural cooling. A total of 8 ultrathin carbon-carbon screen preforms were prepared, all of which passed subsequent carbonization and vapor deposition processes. The final ultrathin carbon-carbon screens all passed thermal environment testing and mechanical property testing.

[0066] In this embodiment, based on parameters such as the thickness, open area ratio, and outer diameter of the screen to be prepared, a specific empirical formula is used to calculate the minimum multifilament strength index required for the reinforcing fiber material. Process verification shows that using phenolic resin as the matrix material for the ultra-thin carbon-carbon screen blank can ensure a high (≥55%) residual carbon rate in the blank after the subsequent carbonization process. Based on parameters such as the finished blank thickness, the unfolded bandwidth of the reinforcing fiber material, the width of the winding coverage area, and the adhesive content of the composite material, a specific empirical formula is used to calculate the winding distance of the reinforcing fiber material.

[0067] This embodiment uses a specific empirical formula to calculate the minimum multifilament strength index required by the reinforcing fiber material, thereby ensuring that the ultra-thin carbon-carbon screen blank is not prone to breakage during subsequent processing; this embodiment identifies a reliable matrix material, thereby ensuring that the ultra-thin carbon-carbon screen has a high (≥55%) residual carbon rate after the carbonization process; this embodiment uses a specific empirical formula to calculate the winding distance of the reinforcing fiber material, thereby ensuring that the finished blank meets the thickness index requirements; this embodiment can prepare ultra-thin carbon-carbon screen blanks that meet the index requirements and have reliable quality.

[0068] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for winding and forming an ultrathin carbon fiber screen blank, characterized in that... include: Select fiber reinforcement materials that meet the minimum multifilament strength and resin matrix materials that meet the residual carbon rate index. Establish a winding system; Fiber-reinforced resin matrix composite material is obtained from fiber-reinforced material and resin matrix material. The fiber-reinforced resin matrix composite material is cured and mechanically processed according to the winding system to obtain an ultra-thin carbon screen blank. The minimum multifilament strength of fiber-reinforced materials is obtained by the following formula: ； in, The minimum multifilament strength of the fiber-reinforced material. As the first coefficient, For open area ratio, The maximum allowable weight for an ultra-thin carbon fiber screen blank; This is the standard gravitational acceleration; This refers to the outer diameter value of the ultra-thin carbon fiber screen blank; This refers to the thickness value of the ultra-thin carbon fiber screen blank. The residual carbon content of the resin matrix material is ≥55%; The winding process includes: the number of winding layers, the winding sequence, and the winding tape spacing; The number of winding layers is 6; The winding sequence is 0°, 60°, 120°, 60°, 120°, 0°; The winding distance is obtained by the following formula: ； in, The distance between the winding strips is the distance between the two strips. As the second coefficient, The maximum allowable weight for an ultra-thin carbon fiber screen blank; The unwinding bandwidth during the winding process of the fiber-reinforced material; This refers to the linear density value of the fiber-reinforced material. This refers to the outer diameter value of the ultra-thin carbon fiber screen blank; This represents the number of winding layers.

2. The winding forming method for ultra-thin carbon-carbon screen blanks according to claim 1, characterized in that: The process of curing and machining fiber-reinforced resin matrix composites according to a winding regime to obtain ultra-thin carbon fiber screen blanks includes: The fiber-reinforced resin matrix composite material is wound onto the mold tooling according to the winding regime. The fiber-reinforced resin matrix composite material and the mold tooling are then placed into the curing equipment and cured according to the curing regime. After curing is complete and the material is allowed to cool naturally, the fiber-reinforced resin matrix composite material along with the mold tooling is removed and machined into an ultra-thin carbon screen blank according to the preset shape and size.

3. The winding forming method for ultra-thin carbon-carbon screen blanks according to claim 2, characterized in that: The mold fixture is a hexagonal winding fixture; wherein, the six corners of the hexagonal winding fixture are respectively machined with a first tightening hole (1), a second tightening hole (2), a third tightening hole (3), a first fixing screw hole (4), a second fixing screw hole (5) and a third fixing screw hole (6).

4. The winding forming method for ultra-thin carbon-carbon screen blanks according to claim 2, characterized in that: The curing process involves maintaining a temperature of 60°C for 3 hours, then raising the temperature to 105°C, maintaining a temperature of 105°C for 4 hours, then raising the temperature to 135°C, maintaining a temperature of 135°C for 4 hours, then raising the temperature to 165°C, maintaining a temperature of 165°C for 3 hours, and finally allowing the temperature to cool naturally to room temperature.

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