Carbon fiber surface etching method and device for enhancing toughness of carbon fiber through ceramic phase

Abstract

A carbon fiber surface etching device for enhancing the toughness of carbon fibers through a ceramic phase comprises a shell, and a carbon fiber surface treatment pipeline is arranged in the shell; one end of the carbon fiber surface treatment pipeline is a carbon fiber tow inlet, and the other end is a carbon fiber tow outlet; the carbon fiber surface treatment pipeline is externally connected with a powder feeder and a powder recovery device through pipelines respectively; and the outer side of the carbon fiber surface treatment pipeline is connected with a heating body. The invention discloses a carbon fiber surface etching method for enhancing the toughness of carbon fibers through a ceramic phase. The carbon fiber surface etching method comprises the following steps that S1, firstly, carbon fiber tows are fed into a carbon fiber surface treatment pipeline from a carbon fiber tow inlet; s2, Zr (CO3) 2 powder is evenly sprayed to the surfaces of the carbon fiber tows through a powder feeder, and redundant Zr (CO3) 2 powder falls into a powder recovery device; and S3, then, enabling the carbon fiber tows attached with the Zr (CO3) 2 powder to pass through a heating area. The carbon fibers produced by the method are better in toughness.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber processing, and in particular to a carbon fiber surface etching method and device for enhancing the toughness of the carbon fiber with a ceramic phase. Background Art

[0002] Carbon fiber is a lightweight, high-strength, high-modulus material that is widely used in aerospace, automobiles, sporting goods, construction and many other industrial fields; the production process of carbon fiber mainly includes the following steps: drawing, drafting, stabilization, carbonization, graphitization, surface treatment, sizing, usually in the graphitization stage by taking the means of increasing the graphitization temperature to increase the graphitization degree of carbon fiber to enhance its performance, this is because in carbon fibers with a high degree of graphitization, the bonding force between graphite crystallites is stronger, can more effectively transmit and withstand stress, thereby improving its tensile strength and compressive strength, for example, in patent CN208472243U, carbon fibers are graphitized by using low-temperature and high-temperature graphitization devices. The carbon fiber is graphitized. In the carbon fiber production process, surface treatment is a key step to improve the bonding performance of carbon fiber and the interface performance of the subsequent composite material. Common surface treatment methods include oxidation treatment, coating treatment, plasma treatment, mechanical treatment, etc., among which oxidation treatment is to introduce oxygen-containing groups (such as carboxyl, hydroxyl, etc.) on the surface of carbon fiber by chemical oxidation or electrochemical oxidation method to improve its surface energy and affinity. This is one of the most commonly used carbon fiber surface treatment methods. For example, in patent CN118668468A, a mixture of sodium salt of organic acid, potassium salt of organic acid and lithium salt of organic acid and inorganic acid is used as an electrolyte to electrochemically oxidize carbon fiber.

[0003] It is worth noting that although carbon fibers with a high degree of graphitization usually have higher strength and modulus, they may exhibit lower toughness. This is because the ordered arrangement of graphite crystallites makes it easier for slippage between graphite layers to occur when subjected to impact or cyclic loads, making the material more susceptible to brittle fracture. In addition, although carbon fibers with a high degree of graphitization have a higher tensile strength, their elastic modulus may also increase, which may lead to a decrease in the elasticity of the material, that is, the material's ability to deform when subjected to stress. On the other hand, existing carbon fiber surface treatment methods are complex and the improvement in carbon fiber performance is single and limited. Summary of the invention

[0004] The present invention aims to provide a method and device for etching the surface of carbon fiber with ceramic phase enhanced toughness. The carbon fiber processed by this method and device can improve the graphitization degree of the carbon fiber to make it have higher strength while ensuring that it has good toughness and a certain deformation ability when subjected to stress.

[0005] To solve the above technical problems, the technical solution of the present invention is:

[0006] A carbon fiber surface etching device with ceramic phase enhanced carbon fiber toughness, comprising a shell, wherein a carbon fiber surface treatment pipeline is arranged in the shell; one end of the carbon fiber surface treatment pipeline is a carbon fiber bundle inlet, and the other end is a carbon fiber bundle outlet; the carbon fiber surface treatment pipeline is located at the carbon fiber bundle inlet end and is connected to a powder feeder for conveying Zr(CO3)2 powder to the carbon fiber surface at the inlet and a powder recovery device for recovering excess Zr(CO3)2 powder through pipelines; the outer side of the carbon fiber surface treatment pipeline is connected to a heating element located in the shell; an insulation layer is connected between the heating element and the shell; and water cooling circulation devices are installed at both ends of the carbon fiber surface treatment pipeline.

[0007] Both ends of the carbon fiber surface treatment pipeline are connected with thermal insulation felt.

[0008] The heating element is a graphite heating element; and the thermal insulation layer is an aluminum silicate thermal insulation layer.

[0009] The water cooling circulation device comprises two spiral cooling pipes respectively spirally wound on the two ends of the carbon fiber surface treatment pipe, two cooling boxes and two pump bodies; the two cooling boxes are both provided with a water inlet cavity, a water outlet cavity and a cooling cavity located between the water inlet cavity and the water outlet cavity; the water inlet cavity and the water outlet cavity are connected by a heat exchange pipe; the heat exchange pipe is located in the cooling cavity, and a refrigeration device for cooling the cooling cavity is also installed in the cooling cavity; the water inlet cavities of the two cooling boxes are respectively connected to a water inlet main pipe through a pipe, and the water outlet cavities of the two cooling boxes are respectively connected to a water outlet main pipe through a pipe; the water outlet main pipe is respectively connected to the water inlet ends of the two spiral cooling pipes through two first branches, and the water inlet main pipe is respectively connected to the water outlet ends of the two spiral cooling pipes through two second branches; the two pump bodies are respectively connected to the two second branches; the two second branches are also equipped with a one-way valve; the two first branches are equipped with an electromagnetic valve.

[0010] The refrigeration device is an air conditioner.

[0011] A method for etching the surface of a carbon fiber with ceramic phase enhanced carbon fiber toughness, using the above-mentioned device for etching the surface of a carbon fiber with ceramic phase enhanced carbon fiber toughness, comprises the following steps:

[0012] S1, firstly, feeding the carbon fiber tow from the carbon fiber tow inlet into the carbon fiber surface treatment pipeline;

[0013] S2, Zr(CO3)2 powder is uniformly sprayed onto the surface of the carbon fiber tow via a powder feeder, and excess Zr(CO3)2 powder falls into a powder recovery device; wherein the carrier gas of the powder feeder is nitrogen or argon, the flow rate of which is 1 to 30 liters / minute, and the rotation speed of the powder feeder is 0.1 to 10 revolutions / minute;

[0014] S3, then, the carbon fiber tow with Zr(CO3)2 powder attached thereto passes through the heating area, and the furnace cavity is heated to 150-1300 degrees Celsius by the heating element, and Zr(CO3)2 is easily decomposed by heat to decompose on the surface of the carbon fiber to generate CO2 and t-ZrO2; wherein, the generated CO2 reacts on the surface of the carbon fiber to generate CO and causes etching to the carbon fiber, and on the other hand, the generated t-ZrO2 reacts with the surface of the carbon fiber at high temperature to form a chemical bond;

[0015] S4, the heated and etched carbon fiber tow is sent out from the carbon fiber tow outlet.

[0016] In the step S2, the carrier gas of the powder feeder is nitrogen at 15 liters / minute, and the rotation speed of the powder feeder is 5 revolutions / minute; in the step S3, the heating element heats the furnace chamber to 500 degrees Celsius.

[0017] The technical effect that can be achieved by the present invention is: a method and device for etching the surface of a carbon fiber with a ceramic phase to enhance the toughness of the carbon fiber, by attaching zirconium carbonate (Zr(CO3)2) powder as a surface modifier to the surface of the carbon fiber, utilizing the property of zirconium carbonate being easily decomposed by heat, to decompose on the surface of the carbon fiber to generate carbon dioxide (CO2) and nano zirconium oxide (t-ZrO2). Among them, the generated carbon dioxide (CO2) reacts on the surface of carbon fiber to generate carbon monoxide (CO), which causes etching to the carbon fiber; on the other hand, the generated nano zirconium oxide (t-ZrO2) reacts with the surface of carbon fiber at high temperature to form chemical bonds; zirconium oxide has three crystalline phases: monoclinic phase (m-ZrO2), tetragonal phase (t-ZrO2) and cubic phase (c-ZrO2), among which the tetragonal phase is transformed into monoclinic phase under stress extrusion. This phase change process absorbs energy, thereby improving the toughness of the material; therefore, the zirconium oxide nanoparticles are evenly dispersed on the surface of carbon fiber and between fiber bundles, and the toughness of carbon fiber can be enhanced by utilizing its stress-induced phase change characteristics; at the same time, the nanoparticles (zirconia) can also play a pinning role in the process of crack propagation, preventing further expansion of the crack, thereby improving the toughness of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0019] Figure 1It is a structural schematic diagram of a carbon fiber surface etching device for enhancing the toughness of carbon fiber with a ceramic phase according to the present invention;

[0020] Figure 2 It is a schematic diagram of the structure of the water cooling circulation device;

[0021] Figure 3 yes Figure 2 A magnified view of part A;

[0022] Figure 4 This is a schematic diagram of the etching principle of the carbon fiber surface to enhance the toughness of the carbon fiber with ceramic phase;

[0023] Figure 5 Interfacial shear strength (IFSS) of untreated and zirconia reinforced monofilament carbon fiber / epoxy composites;

[0024] Figure 6 Stress distribution of (a) untreated and (b) zirconia-reinforced single-filament carbon fiber / epoxy resin composites under shear loading. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0026] See also Figures 1 to 6 .

[0027] A carbon fiber surface etching device with ceramic phase enhanced carbon fiber toughness comprises a shell 7, in which a carbon fiber surface treatment pipe 11 is arranged. Preferably, both ends of the carbon fiber surface treatment pipe 11 are connected with insulation felt 3; one end of the carbon fiber surface treatment pipe 11 is a carbon fiber bundle inlet 2, and the other end is a carbon fiber bundle outlet 10; the carbon fiber surface treatment pipe 11 is located at the carbon fiber bundle inlet 2 ends and is connected to a powder feeder 4 for conveying Zr(CO3)2 powder to the carbon fiber surface at the inlet and a powder recovery device 5 for recovering excess Zr(CO3)2 powder through pipes; the outer side of the carbon fiber surface treatment pipe 11 is connected to a heating element 9 located in the shell 7, and an insulation layer 8 is connected between the heating element 9 and the shell 7. Specifically, the insulation layer 8 is an aluminum silicate insulation layer, and the heating element 9 is a graphite heating element.

[0028] A water cooling circulation device is installed at both ends of the carbon fiber surface treatment pipeline 11. Specifically, the water cooling circulation device includes two spiral cooling pipelines 6 respectively spirally wound at both ends of the carbon fiber surface treatment pipeline 11, two cooling boxes 13 and two pump bodies 14; both cooling boxes 13 are provided with a water inlet cavity 21, a water outlet cavity 22 and a cooling cavity 23 located between the water inlet cavity 21 and the water outlet cavity 22; the water inlet cavity 21 and the water outlet cavity 22 are connected by a heat exchange pipeline 24, the heat exchange pipeline 24 is located in the cooling cavity 23, and a refrigeration device 1 for cooling the cooling cavity 23 is also installed in the cooling cavity 23 2. Specifically, the refrigeration device 12 is an air conditioner; the water inlet cavities 21 of the two cooling boxes 13 are connected to a water inlet pipe 25 through a pipeline, and the water outlet cavities 22 of the two cooling boxes 13 are connected to a water outlet pipe 26 through a pipeline; the water outlet pipe 26 is connected to the water inlet ends of the two spiral cooling pipes 6 through two first branch pipes 27, and the water inlet pipe 25 is connected to the water outlet ends of the two spiral cooling pipes 6 through two second branch pipes 28; the two pump bodies 14 are connected to the two second branch pipes 28, and the two second branch pipes 28 are also equipped with a one-way valve 29; the two first branch pipes 27 are equipped with a solenoid valve 30.

[0029] In the present invention, since the temperature when the monoclinic phase transforms into the tetragonal phase zirconia is relatively high, the furnace often needs to be heated to 1000 degrees Celsius or above, so a water cooling circulation device needs to be invented for supporting use.

[0030] When the water cooling circulation device of the present invention is used, firstly, the two solenoid valves 30 and the two pump bodies 14 are opened, and the water circulation is controlled by the pump body 14. Specifically, the water in the two spiral cooling pipes 6 will rise in temperature after heat exchange with the carbon fiber surface treatment pipe 11, generally rising to about 40 degrees Celsius, and then introduced into the water inlet main pipe 25 through the two second branch pipes 28, and then enter the two cooling boxes 13 for cooling. Specifically, the water entering the cooling box 13 first enters the water inlet cavity 21, and then passes through the heat exchange pipe 24 to enter Into the water outlet cavity 22, and when the water is in the heat exchange pipe 24, the cooling cavity 23 reduces the temperature of the cavity itself and the heat exchange pipe 24 through the refrigeration device 12, so that the water can exchange heat through the heat exchange pipe 24, so that the temperature of the water is reduced, and then it flows into the water outlet cavity 22. At this time, the water temperature is generally around 25 degrees Celsius, and then flows into the two first branch pipes 27 through the water outlet main pipe 26, and finally returns to the two spiral cooling pipes 6 to continue circulating heat exchange, and continuously cools the carbon fiber surface treatment pipe 11.

[0031] In the use of the carbon fiber surface etching device of the present invention for enhancing the toughness of carbon fiber by ceramic phase, the following can be referred to:

[0032] A method for etching the surface of a carbon fiber with ceramic phase enhanced carbon fiber toughness, using the above-mentioned device for etching the surface of a carbon fiber with ceramic phase enhanced carbon fiber toughness, comprises the following steps:

[0033] S1, firstly, a carbon fiber tow 1 is fed into a carbon fiber surface treatment pipeline 11 from a carbon fiber tow inlet 2;

[0034] S2, Zr(CO3)2 powder is uniformly sprayed onto the surface of the carbon fiber tow 1 via a powder feeder 4, and excess Zr(CO3)2 powder falls into a powder recovery device 5; wherein the carrier gas of the powder feeder 4 is nitrogen (N2) or argon (Ar), and its flow rate is 1 to 30 liters / minute, and the rotation speed of the powder feeder 4 is 0.1 to 10 revolutions / minute;

[0035] S3, then, the carbon fiber tow 1 with Zr(CO3)2 powder attached thereto passes through the heating area, and the furnace cavity is heated to 150-1300 degrees Celsius by the heating element 9, and zirconium carbonate is easily decomposed by heat to generate CO2 and t-ZrO2 on the surface of the carbon fiber; wherein the generated CO2 reacts on the surface of the carbon fiber to generate CO and causes etching to the carbon fiber, and on the other hand, the generated t-ZrO2 reacts with the surface of the carbon fiber at high temperature to form a chemical bond;

[0036] S4, the carbon fiber tow 1 after heating and etching is sent out from the carbon fiber tow outlet 10.

[0037] Preferably, in step S2 of the present invention, the carrier gas of the powder feeder 4 is nitrogen (N2) or argon (Ar), and the flow rate thereof is 15 liters / minute, and the rotation speed of the powder feeder 4 is 5 rpm; in step S3, the heating element 9 heats the furnace chamber, i.e., the carbon fiber surface treatment pipeline 11, to 500 degrees Celsius.

[0038] The present invention uses zirconium carbonate (Zr(CO3)2) powder as a surface modifier to attach to the surface of carbon fiber, and utilizes the property that zirconium carbonate is easily decomposed by heat to decompose on the surface of carbon fiber to generate carbon dioxide (CO2) and nano zirconium oxide (t-ZrO2); wherein the generated carbon dioxide (CO2) reacts on the surface of carbon fiber to generate carbon monoxide (CO), which causes etching to the carbon fiber; on the other hand, the generated nano zirconium oxide (t-ZrO2) reacts with the surface of carbon fiber at high temperature to form chemical bonds (reference Figure 4); Zirconia has three crystalline phases: monoclinic phase (m-ZrO2), tetragonal phase (t-ZrO2) and cubic phase (c-ZrO2), among which the tetragonal phase transforms into monoclinic phase under stress extrusion. This phase change process absorbs energy, thereby improving the toughness of the material; therefore, by evenly dispersing zirconium oxide nanoparticles on the surface of carbon fiber and between fiber bundles, the toughness of carbon fiber can be enhanced by utilizing its stress-induced phase change characteristics; at the same time, nanoparticles (zirconia) can also play a pinning role in the process of crack propagation, preventing further expansion of the crack, thereby improving the toughness of the material.

[0039] Figure 5 The interfacial shear strength (IFSS) of untreated and zirconia-reinforced monofilament carbon fiber / epoxy resin composites is shown to be 56MPa and 72MPa, respectively. The interfacial strength of the zirconia-reinforced composite is 29% higher than that of the untreated composite. Figure 6 The stress distribution in the matrix, fiber and interface of the composite unit without treatment and the interface of zirconia reinforced phase under shear load is shown. It can be clearly observed that the stress concentration phenomenon at the interface of the reinforced composite is effectively improved.

[0040] Compared with untreated carbon fibers, the toughness of the carbon fibers is significantly improved. At the same time, the attachment of nano zirconium oxide particles on the surface greatly increases the specific surface area of ​​the carbon fibers, thereby increasing the interfacial volume of the carbon fiber composite material subsequently formed by compounding with the resin, thereby achieving the purpose of increasing the interfacial bonding strength, with the strength increased by 29%.

[0041] By introducing high-hardness and high-strength nanoparticles (zirconia), the effect of pinning cracks is achieved at the interface between carbon fiber and matrix.

[0042] When the carbon fiber composite material with zirconium oxide reinforced phase interface is subjected to compressive stress or shear stress, the tetragonal zirconium oxide particles distributed at the interface consume energy when the martensite transforms into the monoclinic phase, which effectively reduces the stress concentration and inhibits / prevents the formation and expansion of cracks, thereby achieving the effect of enhancing the mechanical properties of the carbon fiber composite material.

Claims

1. A carbon fiber surface etching device for enhancing the toughness of carbon fiber by ceramic phase, comprising a housing (7), characterized in that: A carbon fiber surface treatment pipeline (11) is arranged in the shell (7); one end of the carbon fiber surface treatment pipeline (11) is a carbon fiber bundle inlet (2), and the other end is a carbon fiber bundle outlet (10); the carbon fiber surface treatment pipeline (11) is located at the end of the carbon fiber bundle inlet (2) and is connected to a powder feeder (4) for conveying Zr (CO3) 2 powder to the carbon fiber surface at the inlet and a powder recovery device (5) for recovering excess Zr (CO3) 2 powder through pipelines; the outer side of the carbon fiber surface treatment pipeline (11) is connected to a heating element (9) located in the shell (7); an insulation layer (8) is connected between the heating element (9) and the shell (7); and water cooling circulation devices are installed at both ends of the carbon fiber surface treatment pipeline (11).

2. The carbon fiber surface etching device for enhancing the toughness of carbon fiber with ceramic phase according to claim 1, characterized in that: Both ends of the carbon fiber surface treatment pipeline (11) are connected to thermal insulation felt (3).

3. The carbon fiber surface etching device for enhancing the toughness of carbon fiber with ceramic phase according to claim 1, characterized in that: The heating element (9) is a graphite heating element; and the thermal insulation layer (8) is an aluminum silicate thermal insulation layer.

4. The carbon fiber surface etching device for enhancing the toughness of carbon fiber with ceramic phase according to claim 1, characterized in that: The water cooling circulation device comprises two spiral cooling pipes (6) respectively spirally wound around the two ends of the carbon fiber surface treatment pipe (11), two cooling boxes (13) and two pump bodies (14); the two cooling boxes (13) are both provided with a water inlet cavity (21), a water outlet cavity (22) and a cooling cavity (23) located between the water inlet cavity (21) and the water outlet cavity (22); the water inlet cavity (21) and the water outlet cavity (22) are connected via a heat exchange pipe (24); the heat exchange pipe (24) is located in the cooling cavity (23), and a refrigeration device (12) for cooling the cooling cavity (23) is also installed in the cooling cavity (23); the two cooling boxes The water inlet cavity (21) of the two cooling boxes (13) is connected to a water inlet pipe (25) through a pipeline, and the water outlet cavity (22) of the two cooling boxes (13) is connected to a water outlet pipe (26) through a pipeline; the water outlet pipe (26) is connected to the water inlet ends of the two spiral cooling pipes (6) through two first branch pipes (27), and the water inlet pipe (25) is connected to the water outlet ends of the two spiral cooling pipes (6) through two second branch pipes (28); the two pump bodies (14) are connected to the two second branch pipes (28); the two second branch pipes (28) are also equipped with a one-way valve (29); and the two first branch pipes (27) are equipped with an electromagnetic valve (30).

5. The carbon fiber surface etching device for enhancing the toughness of carbon fiber with ceramic phase according to claim 1, characterized in that: The refrigeration device (12) is an air conditioner.

6. A method for etching the surface of a carbon fiber to enhance the toughness of the carbon fiber by a ceramic phase, characterized in that: A carbon fiber surface etching device using a ceramic phase to enhance the toughness of carbon fiber according to any one of claims 1 to 5, comprising the following steps: S1, firstly, feeding a carbon fiber tow (1) from a carbon fiber tow inlet (2) into a carbon fiber surface treatment pipeline (11); S2, Zr(CO3)2 powder is uniformly sprayed onto the surface of the carbon fiber tow (1) via a powder feeder (4), and excess Zr(CO3)2 powder falls into a powder recovery device (5); wherein the carrier gas of the powder feeder (4) is nitrogen or argon, and its flow rate is 1 to 30 liters / minute, and the rotation speed of the powder feeder (4) is 0.1 to 10 revolutions / minute; S3, then, the carbon fiber bundle (1) with Zr(CO3)2 powder attached thereto passes through a heating area, and the furnace cavity is heated to 150-1300 degrees Celsius by a heating element (9), and zirconium carbonate is easily decomposed by heat to generate CO2 and t-ZrO2 on the surface of the carbon fiber; wherein the generated CO2 reacts on the surface of the carbon fiber to generate CO and causes etching to the carbon fiber, and on the other hand, the generated t-ZrO2 reacts with the surface of the carbon fiber at high temperature to form a chemical bond; S4, the heated and etched carbon fiber bundle (1) is sent out from the carbon fiber bundle outlet (10).

7. The method for etching the surface of a carbon fiber with ceramic phase to enhance the toughness of the carbon fiber according to claim 6, characterized in that: In the step S2, the carrier gas of the powder feeder (4) is nitrogen (N2) at 15 liters / minute, and the rotation speed of the powder feeder (4) is 5 revolutions / minute; in the step S3, the heating element (9) heats the furnace chamber to 500 degrees Celsius.

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