阅读说明：本技术 基于碳纳米材料的非热压罐电致成型复合材料方法 (Carbon nano material-based non-autoclave electroformed composite material method ) 是由 何霁 江晟达 于 2021-09-03 设计创作，主要内容包括：本发明提供了一种基于碳纳米材料的非热压罐电致成型复合材料方法,包括以下步骤,在所设计产品结构中的预浸料或干布间铺叠碳纳米超薄薄膜夹层,提供层间毛细压力并增韧结构,提高厚度方向温度均匀度。而在结构外侧与内侧分别布置被无孔铁氟龙薄膜包裹的碳纳米薄膜则作为电阻加热器,其两端与铜片粘结接入高压发生器,并根据所设计产品结构于碳纳米薄膜各处布置热电偶,进行实时的温度监控,无孔铁氟龙薄膜主要起到脱模与绝缘效果。最后以真空袋封装并以隔热材料包裹避免热量散失,大大减少电能消耗。抽真空后开启电压,进行加热固化,固化过程中,可以通过监测热电偶的实时温度与调节电压大小实现固化温度变化过程的控制。(The invention provides a carbon nano material-based non-autoclave electroformed composite material method, which comprises the following steps of laying a carbon nano ultrathin film interlayer between prepreg or dry cloth in a designed product structure, providing interlayer capillary pressure and toughening the structure, and improving the temperature uniformity in the thickness direction. The carbon nano-films wrapped by the nonporous Teflon films are respectively arranged on the outer side and the inner side of the structure and are used as resistance heaters, the two ends of the carbon nano-films are bonded with the copper sheet and are connected into a high-voltage generator, thermocouples are arranged at the positions of the carbon nano-films according to the designed product structure to carry out real-time temperature monitoring, and the nonporous Teflon films mainly play roles in demolding and insulating. Finally, the vacuum bag is used for packaging and the heat insulation material is used for wrapping so as to avoid heat loss and greatly reduce the power consumption. After vacuumizing, the voltage is started to heat and cure, and in the curing process, the control of the curing temperature change process can be realized by monitoring the real-time temperature of the thermocouple and adjusting the voltage.)

1. A carbon nano material-based non-autoclave electroformed composite material method is characterized by comprising the following steps:

step S1: laying a carbon nano ultrathin film interlayer between the prepreg or the dry cloth in the designed product structure to provide interlayer capillary pressure;

step S2: the outer side and the inner side of the product structure are respectively provided with a carbon nano film wrapped by a non-porous Teflon film as a resistance heater, and two ends of the carbon nano film are bonded with a copper sheet and connected to a high-voltage generator;

step S3: according to the designed product structure, thermocouples are arranged at all positions of the carbon nano film to carry out real-time temperature monitoring;

step S4: encapsulating with a vacuum bag and wrapping the product structure with an insulating material;

step S5: and (5) starting voltage after vacuumizing, and heating and curing.

2. The carbon nanomaterial-based non-autoclave electroformed composite method as recited in claim 1, characterized in that the carbon nanomaterial interlayer is a carbon nanofiber membrane with a fiber diameter of between 100 and 1000nm, a single-walled or multi-walled carbon nanotube membrane with a carbon tube diameter of between 5 and 50nm, or a membrane with single-walled or multi-walled carbon nanotubes attached or grown on carbon nanofibers within this dimension range, and the thickness of the carbon nanomaterial interlayer is between 5 and 20 μm.

3. The method as claimed in claim 1, wherein the carbon nano-film used as the resistance heater is a carbon nano-fiber film with a fiber diameter of 100-1000nm, a single-walled or multi-walled carbon nanotube film with a carbon tube diameter of 5-50nm and a graphene film with a thickness of 50-1000 μm.

4. The carbon nanomaterial-based non-autoclave electroformed composite method according to claim 1, characterized in that a thermocouple feeds back temperature in real time, a high voltage generator adjusts voltage according to the fed-back temperature, and the high voltage generator records input voltage, current, and power consumption.

5. The carbon nanomaterial-based non-autoclave electroformed composite method of claim 1, wherein the designed product structure comprises a laminate layup structure of a multi-layer material stack.

6. The carbon nanomaterial-based non-autoclave electroformed composite method according to claim 5, characterized in that a carbon nanomaterial interlayer is laid every time a layer of prepreg or dry cloth is laid.

7. The method of claim 1, wherein the matrix of the composite material comprises phenolic resin, polyetheretherketone resin, epoxy resin, bismaleimide resin or polyimide resin, and the reinforcement comprises carbon fiber, glass fiber, silicon boron nitride fiber, basalt fiber, alumina fiber, boron fiber, natural ramie fiber or bamboo fiber.

8. The carbon nanomaterial-based non-autoclave electroformed composite method of claim 1, wherein the composite forming method comprises a prepreg vacuum bag method, a resin film infiltration method, or a vacuum liquid transfer method.

9. The carbon nanomaterial-based non-autoclave electroformed composite material method according to claim 1, characterized in that the temperature during curing can be achieved by adjusting the voltage.

Technical Field

The invention relates to the technical field of composite material structure forming, in particular to a carbon nano material-based non-autoclave electroformed composite material method.

Background

In the aspect of the existing high-performance fiber reinforced resin matrix composite material forming technology, the autoclave process can effectively eliminate the defects of air bubbles, cavities and the like caused by the flowing of a matrix, improves the fiber body composition, and is suitable for forming various complex structures, for example, T800 carbon fiber reinforced bismaleimide resin prepreg needs to be cured and formed in an autoclave at the temperature of 210 ℃ and the pressure of 1.2MPa, and effectively avoids the defect that air is retained in viscous bismaleimide resin to form and influence the rigidity and the strength.

However, it has to be acknowledged that the process forming part is often limited by the volume and pressure bearing limit of the tank body, the risk of high-temperature and high-pressure gas storage and the use of a large amount of consumables limit the popularization process of the process forming part, and the process forming part is only widely applied in the aerospace field at present. The special-shaped composite material part is difficult to fully fill the cylindrical cavity of the tank body, a large amount of energy is consumed on gas which is not in direct contact with the molded part, the gas can further prolong the cooling and pressure relief time in the cooling stage, and the time cost of high-temperature and high-pressure container guarding personnel is increased, so the tank opening and curing cost is fixed and high and is not determined by the part, the process is not flexible enough in the production and manufacturing process, and the decision cost of management personnel is increased. This is a bottleneck that restricts the wide application of high performance composite materials.

The vacuum bag process without high pressure environment improves the above problems, but the forming quality is much inferior to the autoclave process, the layering is difficult to compact by one atmosphere, the product is still limited by the fixed oven shape, the energy waste is serious, and the vacuum bag process is only a low-cost production means. On the other hand, in both autoclave and oven, the heat provided by the autoclave and oven for curing the product is conducted from outside to inside by the resin between layers, and the resin with lower thermal conductivity is easy to generate temperature gradient in the conduction process to cause thermal expansion cracking between layers, thereby affecting the curing quality. Therefore, how to apply heat to cure more accurately and uniformly and make interlayer bonding more compact on the basis of not relying on a high-pressure environment is one of important directions for researching a non-autoclave forming method.

In order to solve the problems, the patent CN109367060A discloses a microwave curing method, which reduces the defects of the vacuum bag forming composite material based on a vibration table and a microwave generator, provides heat, but the shape of the cavity still needs to be fixed and then the cavity is put into a workpiece; patent CN112743921A is based on the sequence of laying resin films with gradient viscosity between layers, and heating to melt and infiltrate the resin films to reduce defects, but it does not address the problems of conformability of resin films for complicated shaped articles and interlayer resin thickness. Therefore, there is still a need in the art to provide more advanced curing apparatus and method for high performance fiber reinforced resin matrix composite.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a non-autoclave electroformed composite material method based on carbon nano-materials.

The invention provides a carbon nano-material-based non-autoclave electroformed composite material method, which comprises the following steps:

step S1: laying a carbon nano ultrathin film interlayer between the prepreg or the dry cloth in the designed product structure to provide interlayer capillary pressure;

step S2: the outer side and the inner side of the product structure are respectively provided with a carbon nano film wrapped by a non-porous Teflon film as a resistance heater, and two ends of the carbon nano film are bonded with a copper sheet and connected to a high-voltage generator;

step S3: according to the designed product structure, thermocouples are arranged at all positions of the carbon nano film to carry out real-time temperature monitoring;

step S4: encapsulating with a vacuum bag and wrapping the product structure with an insulating material;

step S5: and (5) starting voltage after vacuumizing, and heating and curing.

Preferably, the carbon nanometer ultrathin film interlayer is a carbon nanometer fiber film with the fiber diameter distributed between 100-1000nm, a single-wall or multi-wall carbon nanometer tube film with the carbon tube diameter distributed between 5-50nm, or a film with single-wall or multi-wall carbon nanometer tubes attached or grown on the carbon nanometer fibers in the size range, and the thickness of the carbon nanometer ultrathin film interlayer is distributed between 5-20 μm.

Preferably, the carbon nano film used as the resistance heater is a carbon nano fiber film with the fiber diameter distributed between 100-1000nm, a single-wall or multi-wall carbon nano tube film with the carbon tube diameter distributed between 5-50nm and a graphene film, and the thickness is distributed between 50-1000 μm.

Preferably, the thermocouple feeds back the temperature in real time, the high voltage generator adjusts the voltage according to the fed back temperature, and the high voltage generator records the input voltage, the current and the power consumption.

Preferably, the designed product structure comprises a laminate lay-up structure of a stack of layers of material.

Preferably, whenever a layer of prepreg or dry cloth is laid, a carbon nano ultrathin film interlayer is laid.

Preferably, the matrix of the composite material comprises phenolic resin, polyether ether ketone resin, epoxy resin, bismaleimide resin or polyimide resin, and the reinforcement comprises carbon fiber, glass fiber, silicon boron nitrogen fiber, basalt fiber, alumina fiber, boron fiber, natural ramie fiber or bamboo fiber.

Preferably, the method of forming the composite material comprises a vacuum bag method of prepreg, a resin film infiltration method or a vacuum liquid transfer method.

Preferably, the temperature during curing can be achieved by adjusting the voltage.

Compared with the prior art, the invention has the following beneficial effects:

1. the carbon nano film is used as the resistance heater for curing, so that the problems of the conventional technology for heating based on convection in the aspects of effective space utilization rate, high-temperature and high-pressure gas storage and the like are solved.

2. The invention can be applied to the manufacture of all fiber reinforced resin matrix composite material structures by matching the soft film with the vacuum bag method under reasonable design, and can be repeatedly utilized.

3. When a complex structure made of a composite material, such as a connecting ring or a control surface structure of an air-to-air missile, is manufactured, a large variable thickness area is often encountered, a large temperature gradient is generated under a convection heat source, microcracks are generated due to thermal expansion, a conventional forming technology can select proper reduction of curing speed or neglect the curing speed, but the conventional forming technology is used as a contact type carbon nano film resistance heater, the heating temperature can be controlled completely by adjusting the thickness of carbon nano films in different areas, different curing temperatures required by different structural areas are met, and the forming quality and efficiency are further improved.

4. According to the invention, the carbon nano ultrathin film is used as an interlayer, the specific capillary effect of the micro-nano porous structure is utilized, the interlayer pressure is increased, and the polymer matrix is absorbed into the interlayer region, so that the part can obtain the composite material with compact interlayer and no defects without a high-pressure environment.

5. The carbon material between layers of the invention can improve the temperature conduction in the thickness direction, further accelerate the curing process and improve the uniformity of the temperature field.

6. In the pressurizing process, the soft and porous interlayer with high specific surface area is compressed and compacted, and the soft and porous interlayer serving as an ultra-light nano porous material has little influence on the resin body and the structure thickness.

7. The carbon nano interlayer is convenient to use, does not cause obstruction to the forming process, and is suitable for various forming methods.

8. The composite material adopting the interlayer is filled with nano-scale materialsCarbon (C)Fibres or carbon tubes, which require interlaminar destructionCarbon (C)The fiber or the carbon tube is pulled out or broken, a large amount of energy is absorbed, the crack propagation between layers is effectively delayed, and compared with the conventional composite material with poorer interlayer performance, the interlayer stripping resistance and the impact delamination resistance are greatly improved.

9. The invention can improve the electromagnetic shielding effect of the composite material structure because the interlayer is more compact and the conductive carbon nano material exists.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic diagram of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

The invention provides a carbon nano-material-based non-autoclave electroformed composite material method, which comprises the following steps:

s1, laying a carbon nano ultrathin film interlayer between the prepregs or the dry cloth in the designed product structure to provide interlayer capillary pressure;

s2, arranging carbon nano films wrapped by nonporous Teflon films on the outer side and the inner side of the structure respectively to serve as resistance heaters, and connecting the two ends of the carbon nano films and copper sheets into a high-voltage generator in a bonding manner, wherein the nonporous Teflon films mainly play a role in demolding and insulating, and are convenient for recycling of the resistance heaters;

s3, arranging thermocouples at all positions of the carbon nano film according to the designed product structure, and carrying out real-time temperature monitoring;

s4, finally, packaging the bag with a vacuum bag and wrapping the bag with a heat insulating material to avoid heat loss;

and S5, starting voltage after vacuumizing, heating and curing, and controlling the curing temperature by adjusting the voltage in the curing process.

The carbon nanometer ultrathin film interlayer is a carbon nanometer fiber film with the fiber diameter distributed between 100 and 1000nm, a single-wall or multi-wall carbon nanometer tube film with the carbon tube diameter distributed between 5 and 50nm, or a film with single-wall or multi-wall carbon nanometer tubes attached or grown on the carbon nanometer fibers in the size range. The thickness distribution is between 5 and 20 mu m.

The carbon nano film used as the resistance heater is a carbon nano fiber film with the fiber diameter distributed between 100 and 1000nm, a single-wall or multi-wall carbon nano tube film with the carbon tube diameter distributed between 5 and 50nm and a graphene film. The thickness distribution is 50-1000 μm.

The method can control the heating temperature by increasing or decreasing the voltage, the temperature adjusts the voltage by the actual temperature of the thermocouple feedback system, and the high-voltage generator records the input voltage, the current and the power consumption.

The method can adjust the thickness of the carbon nano film used as a resistance heater according to the most suitable curing temperature of different structural areas of the designed product to control the heating temperature.

The method can select different types of forming modes according to the designed product application and requirements, and comprises a prepreg vacuum bag method, a resin film infiltration method or a vacuum liquid transfer method.

The method in combination with the vacuum bag can be manufactured for different complex structures and is not limited to structures such as plates, barrels, joints and the like.

The matrix adopted by the fiber reinforced resin matrix composite material comprises phenolic resin, polyether-ether-ketone resin, epoxy resin, bismaleimide resin or polyimide resin, and the reinforcement comprises carbon fiber, glass fiber, silicon-boron-nitrogen fiber, basalt fiber, alumina fiber, boron fiber, natural ramie fiber or bamboo fiber.

The carbon nanofiber membrane with the relatively large fiber diameter can further carry magnetic materials such as nickel ferrite and the like or deposit conductive materials such as nickel-copper alloy and the like, so that the electromagnetic shielding performance or the conductive performance of the composite material is improved, and the functionality of the composite material is enhanced.

Example 1:

the embodiment of the invention relates to a carbon nano material-based non-autoclave electroformed composite material method, AS shown in figure 1, the carbon nano material-based non-autoclave electroformed composite material method comprises a vacuum bag 1, an air-permeable felt 2, a thermocouple and a host machine 3 thereof, a non-porous Teflon film 4, a high-pressure generator 5, a highly oriented multi-walled carbon nanotube thin layer 6 with the diameter of 5-10nm and the thickness of 20 mu m, a Hexcel AS4/8552 aviation-grade carbon fiber unidirectional tape prepreg 7, the sheet resistance of 5 omega/port, a carbon nanotube resistance heater 8 with the thickness of 40 mu m, a vacuum valve 9, sealing putty 10, a bottom plate 11 and a heat insulation layer 12.

The device and the method are used for curing the Hexcel AS4/8552 carbon fiber unidirectional tape prepreg commonly used on the rear fuselage skin of the aviation civil aircraft, and the steps are AS follows.

S1, laying the nonporous Teflon film 4, the carbon nanotube resistance heater 8 and the nonporous Teflon film 4 on the bottom plate 11 in sequence;

s2, 16 layers [0 °/90 °/45 ° ] according to design]_2SSequentially stacking the prepreg 7 on the quasi-isotropic laminated plate stacking scheme, wherein in the stacking process, a layer of highly-oriented multi-walled carbon nanotube thin layer 6 needs to be laid every other layer of prepreg 7, and compacting and ironing the prepreg with an electric iron by using a roller;

s3, laying a thermocouple 3 on the upper and lower surfaces of the laminated plate for detecting temperature;

s4, laying the nonporous Teflon film 4, the carbon nanotube resistance heater 8 and the nonporous Teflon film 4 on the top surface of the laminated plate again;

s5, placing the air-permeable felt 2, and wrapping the vacuum bag 1 on the bottom plate by using sealing putty 10 to ensure that the vacuum bag is sealed and airtight, and only keeping the vacuum valve 9 to be communicated with the external atmosphere;

s6, fully coating the heat insulation coating 12 on the outer side of the vacuum bag 1 to prevent temperature loss;

s7, opening the vacuum valve 9, connecting a vacuum pump to pump vacuum, and compressing and compacting the multilayer material;

s8, controlling the high-voltage generator 5 by monitoring the real-time response temperature of the thermocouple 3, firstly keeping the curing temperature at 110 ℃ for 60min, then keeping the curing temperature at 180 ℃ for 120min, and controlling the heating rate to be 3 ℃/min;

and S9, naturally cooling and demolding, and recovering the carbon nano tube resistance heater 8.

The porosity of the resulting composite laminated sheet was 0.0 vol%, and the interlaminar shear strength of the resulting composite laminated sheet was 93.6 MPa. In which the thin highly oriented multi-walled carbon nanotube layer 6, 20 μm high, is compressed to 5 μm in the interlayer region, with little effect on laminate thickness. The 2 x 60 x 50mm composite laminate was cured using a carbon nanotube resistance heating process with a total energy consumption of 118.8 kJ.

Comparative example 1

The same Hexcel AS4/8552 carbon fiber unidirectional tape prepreg was cured using a vacuum bag method using 0.006m without using the high voltage generator 5, the highly oriented multi-walled carbon nanotube sheet 6, and the carbon nanotube resistance heater 8³The oven is heated, the other devices are the same, and in the curing process, the vacuum is pumped at the atmospheric pressureThen, the mixture is also kept at the curing temperature of 110 ℃ for 60min, then kept at the curing temperature of 180 ℃ for 120min, the heating rate is controlled to be 3 ℃/min, and the mixture is naturally cooled and demoulded.

The porosity of the composite laminated plate is 1.65 +/-0.05 vol%, and the interlaminar shear strength of the composite laminated plate is 66.4 MPa. More pores are formed, and the interlaminar shear strength is reduced by 27 percent compared with the non-autoclave electroformed composite material laminated plate based on the carbon nano material. The use of an oven to cure 2 x 60 x 50mm composite laminates had a total energy consumption of 13.7MJ, which increased 115 times the energy consumption of the carbon nanomaterial-based non-autoclave electroformed composite process.

Comparative example 2

Curing the same Hexcel AS4/8552 carbon fiber unidirectional tape prepreg by using an autoclave method, wherein the devices are the same except that a high pressure generator 5, a highly oriented multi-walled carbon nanotube thin layer 6 and a carbon nanotube resistance heater 8 are not used, in the curing process, vacuumizing is carried out, then, under six atmospheric pressures (0.6MPa), the curing temperature of 110 ℃ is kept for 60min, then, the curing temperature of 180 ℃ is kept for 120min, the heating rate is controlled to be 3 ℃/min, and natural cooling and demolding are carried out.

The porosity of the resulting composite laminated sheet was 0.0 vol%, and the interlaminar shear strength of the resulting composite laminated sheet was 91.2 MPa. The porosity was the same as for the carbon nanomaterial-based non-autoclave electroformed composite laminates, with a slightly lower interlaminar shear strength.

Example 2:

the embodiment of the invention relates to a carbon nano material-based non-autoclave electroformed composite material method, as shown in figure 1, the carbon nano material-based non-autoclave electroformed composite material method comprises a vacuum bag 1, an air-permeable felt 2, a thermocouple and a host machine 3 thereof, a non-porous Teflon film 4, a high-pressure generator 5, a continuous carbon nano fiber film 6 with the diameter of 300nm and the thickness of 22 mu m, a lily space T300/epoxy resin carbon fiber unidirectional tape prepreg 7, the sheet resistance is 5 omega/port, a carbon nano tube resistance heater 8 with the thickness of 40 mu m, a vacuum valve 9, sealing putty 10, a bottom plate 11 and a heat insulation layer 12.

The device and the method of the invention are used for curing a commonly used lily space T300/epoxy resin carbon fiber sheetPrepreg to tape and comparison of interlaminar two-type fracture toughness G_ⅡCPerformance, procedure is as follows.

S1, laying the nonporous Teflon film 4, the carbon nanotube resistance heater 8 and the nonporous Teflon film 4 on the bottom plate 11 in sequence;

s2, 24 layers [0 DEG ] according to the design]₂₄Sequentially stacking the prepreg 7 on the single-layer laminated plate stacking scheme, wherein in the stacking process, when 12 layers of the prepreg 7 are fully paved, a layer of continuous carbon nanofiber membrane 6 needs to be paved, a layer of nonporous Teflon film 4 with the length of 35mm is padded along the fiber direction and used for prefabricating defect cracks, and a roller and an electric iron are used for compacting and ironing;

s3, laying a thermocouple 3 on the upper and lower surfaces of the laminated plate for detecting temperature;

s4, laying the nonporous Teflon film 3, the carbon nanotube resistance heater 8 and the nonporous Teflon film 3 on the top surface of the laminated plate again;

s5, placing the air-permeable felt 2, and wrapping the vacuum bag 1 on the bottom plate by using sealing putty 10 to ensure that the vacuum bag is sealed and airtight, and only keeping the vacuum valve 9 to be communicated with the external atmosphere;

s6, fully coating the heat insulation coating 12 on the outer side of the vacuum bag 1 to prevent temperature loss;

s7, opening the vacuum valve 9, connecting a vacuum pump to pump vacuum, and compressing and compacting the multilayer material;

s8, controlling the high-voltage generator 5 by monitoring the real-time response temperature of the thermocouple 3, firstly keeping the curing temperature of 80 ℃ for 30min, then keeping the curing temperature of 120 ℃ for 90min, and controlling the heating rate to be 3 ℃/min;

and S9, naturally cooling and demolding, and recovering the carbon nano tube resistance heater 8.

Interlaminar two-type fracture toughness G of the obtained composite material laminated plate_ⅡCIs 1.54kJ/m². Among them, the continuous carbon nanofiber film 6 having a height of 22 μm sufficiently fills the interlayer resin region, and has little influence on the laminate thickness.

Comparative example 1

Curing the same lily boat tai T300/epoxy resin carbon fiber unidirectional tape prepreg by using a vacuum bag method, heating by using an oven except for not using a high-pressure generator 5, a continuous carbon nanofiber membrane 6 and a carbon nanotube resistance heater 8, keeping the curing temperature of 80 ℃ for 30min, then keeping the curing temperature of 120 ℃ for 90min at the same temperature rise rate of 3 ℃/min under one atmospheric pressure in the curing process after vacuumizing, and naturally cooling and demolding.

Interlaminar two-type fracture toughness G of the obtained composite material laminated plate_ⅡCIs 1.24kJ/m². Interlaminar two-type fracture toughness G_ⅡCCompared with the non-autoclave electroformed composite material laminate based on the carbon nano-material, the weight loss is reduced by 24 percent.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.