阅读说明：本技术 一种改性碳纤维及其制备方法、改性碳纤维增强铝基复合材料及其制备方法 (Modified carbon fiber and preparation method thereof, modified carbon fiber reinforced aluminum matrix composite and preparation method thereof ) 是由 张宇博 李廷举 王同敏 刘嘉鸣 曹志强 卢一平 接金川 康慧君 陈宗宁 郭恩宇 于 2020-06-18 设计创作，主要内容包括：本发明涉及复合材料技术领域,尤其涉及一种改性碳纤维及其制备方法、改性碳纤维增强铝基复合材料及其制备方法。采用本发明的方法制备的改性碳纤维其表面镀层均匀,且碳纤维与镀层间的结合强度高,有利于提高碳纤维增强铝基复合材料的综合性能。此外,与传统的敏化、活化两步法工艺流程相比,本发明采用一步法胶体钯活化工艺大幅度降低了活化工艺所需温度,极大地缩短了活化工艺所需时间,从而显著提升了化学镀工艺的效率。(The invention relates to the technical field of composite materials, in particular to a modified carbon fiber and a preparation method thereof, and a modified carbon fiber reinforced aluminum matrix composite material and a preparation method thereof. The modified carbon fiber prepared by the method has uniform surface coating, and the bonding strength between the carbon fiber and the coating is high, thereby being beneficial to improving the comprehensive performance of the carbon fiber reinforced aluminum matrix composite. In addition, compared with the traditional sensitization and activation two-step process flow, the method adopts the one-step colloidal palladium activation process to greatly reduce the temperature required by the activation process and greatly shorten the time required by the activation process, thereby obviously improving the efficiency of the chemical plating process.)

1. A preparation method of modified carbon fiber is characterized by comprising the following steps:

sequentially removing glue and oil from the carbon fiber to obtain oil-removed carbon fiber;

mixing the deoiled carbon fiber with a roughening solution, and then carrying out roughening treatment to obtain roughened carbon fiber; the coarsening liquid comprises: 180-220 mL/L of concentrated nitric acid, 180-220 mL/L of concentrated sulfuric acid and the balance of water;

mixing the coarsened carbon fiber with a colloidal palladium activation solution, and activating to obtain activated carbon fiber; the preparation raw materials of the colloidal palladium activating solution comprise: 0.3-0.7 g/L of palladium chloride, 30-40 g/L of stannous chloride, 40-60 mL/L of concentrated hydrochloric acid, 150-200 g/L of sodium chloride, 5-15 g/L of metallic tin and the balance of water;

mixing the activated carbon fibers with a dispergation solution, and dispergating to obtain dispergated carbon fibers;

and immersing the dispergated carbon fiber into metal deposition liquid for metal deposition to obtain the modified carbon fiber.

2. The method according to claim 1, wherein the roughening treatment is carried out at a temperature of 30 to 50 ℃ for 10 to 20 min; the roughening treatment is carried out under ultrasonic conditions.

3. The method according to claim 1, wherein the activation temperature is 20 to 28 ℃ and the activation time is 3 to 8 min.

4. The method of claim 1, wherein the metal deposition bath comprises: 15-25 g/L nickel sulfate, 15-25 g/L sodium hypophosphite, 15-25 mL/L lactic acid and the balance of water, wherein the pH value of the metal deposition liquid is 3.5-4.5.

5. The method according to claim 1 or 4, wherein the metal deposition temperature is 50 to 70 ℃ and the time is 20 to 40 min.

6. The production method according to claim 1, wherein the peptizing solution comprises: 80-120 mL/L of concentrated hydrochloric acid and the balance of water.

7. Modified carbon fibers produced by the production method according to any one of claims 1 to 6; the modified carbon fiber comprises carbon fiber and a metal coating attached to the surface of the carbon fiber.

8. A modified carbon fiber reinforced aluminum matrix composite comprising the modified carbon fiber of claim 7 and an aluminum alloy matrix; the aluminum alloy matrix wraps the modified carbon fibers.

9. The modified carbon fiber reinforced aluminum matrix composite material as claimed in claim 8, wherein the modified carbon fiber reinforced aluminum matrix composite material contains 1-5% by volume of modified carbon fibers.

10. A process for the preparation of a modified carbon fibre reinforced aluminium matrix composite as claimed in claim 8 or 9, comprising the steps of:

preheating the aluminum alloy back plate to obtain a preheated back plate;

preheating the modified carbon fiber to obtain preheated modified carbon fiber;

and laying the preheated modified carbon fibers on the upper surface of the preheating back plate, then pouring an aluminum alloy melt on the surface of the laid preheated modified carbon fibers, completely covering the modified carbon fibers, and rolling after the covering layer is solidified into a semi-solid state to obtain the modified carbon fiber reinforced aluminum-based composite material.

Technical Field

The invention relates to the technical field of composite materials, in particular to a modified carbon fiber and a preparation method thereof, and a modified carbon fiber reinforced aluminum matrix composite material and a preparation method thereof.

Background

The carbon fiber reinforced aluminum-based composite material has excellent comprehensive properties of high specific strength, high specific modulus, low thermal expansion coefficient, corrosion resistance, thermal aging resistance and the like, and is taken as a powerful competitor and a substitute of the traditional composite material and is well valued by researchers at home and abroad.

However, the wettability between the carbon fiber and the aluminum matrix is poor, so that the interface bonding strength between the carbon fiber and the aluminum matrix is low. In order to improve the wettability between the carbon fiber and the aluminum matrix, the surface of the carbon fiber is usually modified by electroless metal plating. The traditional chemical plating modification process comprises the following steps: the method comprises the steps of degumming, deoiling, coarsening, sensitizing, activating and depositing, but the plating layer obtained by the method is uneven, the bonding strength of the plating layer and carbon fibers is low, and the comprehensive mechanical property of the carbon fiber reinforced aluminum matrix composite material is influenced.

Disclosure of Invention

The invention aims to provide a modified carbon fiber and a preparation method thereof, a modified carbon fiber reinforced aluminum matrix composite and a preparation method thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of modified carbon fibers, which comprises the following steps:

sequentially removing glue and oil from the carbon fiber to obtain oil-removed carbon fiber;

mixing the deoiled carbon fiber with a roughening solution, and then carrying out roughening treatment to obtain roughened carbon fiber; the coarsening liquid comprises: 180-220 mL/L of concentrated nitric acid, 180-220 mL/L of concentrated sulfuric acid and the balance of water;

mixing the coarsened carbon fiber with a colloidal palladium activation solution, and activating to obtain activated carbon fiber; the preparation raw materials of the colloidal palladium activating solution comprise: 0.3-0.7 g/L of palladium chloride, 30-40 g/L of stannous chloride, 40-60 mL/L of concentrated hydrochloric acid, 150-200 g/L of sodium chloride, 5-15 g/L of metallic tin and the balance of water;

mixing the activated carbon fibers with a dispergation solution, and dispergating to obtain dispergated carbon fibers;

and immersing the dispergated carbon fiber into metal deposition liquid for metal deposition to obtain the modified carbon fiber.

Preferably, the temperature of the roughening treatment is 30-50 ℃, and the time is 10-20 min; the roughening treatment is carried out under ultrasonic conditions.

Preferably, the activation temperature is 20-28 ℃, and the activation time is 3-8 min.

Preferably, the metal deposition solution comprises: 15-25 g/L nickel sulfate, 15-25 g/L sodium hypophosphite, 15-25 mL/L lactic acid and the balance of water, wherein the pH value of the metal deposition liquid is 3.5-4.5.

Preferably, the temperature of metal deposition is 50-70 ℃, and the time is 20-40 min.

Preferably, the peptizing solution comprises: 80-120 mL/L of concentrated hydrochloric acid and the balance of water.

The invention provides the modified carbon fiber prepared by the preparation method in the scheme; the modified carbon fiber comprises carbon fiber and a metal coating attached to the surface of the carbon fiber.

The invention provides a modified carbon fiber reinforced aluminum matrix composite, which comprises the modified carbon fiber and an aluminum alloy matrix in the scheme; the aluminum alloy matrix wraps the modified carbon fibers.

Preferably, the volume percentage of the modified carbon fibers in the modified carbon fiber reinforced aluminum matrix composite material is 1-5%.

The invention provides a preparation method of the modified carbon fiber reinforced aluminum matrix composite material, which comprises the following steps:

preheating the aluminum alloy back plate to obtain a preheated back plate;

preheating the modified carbon fiber to obtain preheated modified carbon fiber;

and laying the preheated modified carbon fibers on the upper surface of the preheating back plate, then pouring an aluminum alloy melt on the surface of the laid preheated modified carbon fibers, completely covering the modified carbon fibers, and rolling after the covering layer is solidified into a semi-solid state to obtain the modified carbon fiber reinforced aluminum-based composite material.

The invention provides a preparation method of modified carbon fibers, which comprises the following steps: sequentially removing glue and oil from the carbon fiber to obtain oil-removed carbon fiber; mixing the deoiled carbon fiber with a roughening solution, and then carrying out roughening treatment to obtain roughened carbon fiber; the coarsening liquid comprises: 180-220 mL/L of concentrated nitric acid, 180-220 mL/L of concentrated sulfuric acid and the balance of water; mixing the coarsened carbon fiber with a colloidal palladium activation solution, and activating to obtain activated carbon fiber; the preparation raw materials of the colloidal palladium activating solution comprise: 0.3-0.7 g/L of palladium chloride, 30-40 g/L of stannous chloride, 40-60 mL/L of concentrated hydrochloric acid, 150-200 g/L of sodium chloride, 5-15 g/L of metallic tin and the balance of water; mixing the activated carbon fibers with a dispergation solution, and dispergating to obtain dispergated carbon fibers; and immersing the dispergated carbon fiber into metal deposition liquid for deposition to obtain the modified carbon fiber.

The method removes the protective glue on the surface of the carbon fiber by using the glue removal, further cleans the surface of the carbon fiber by using the oil removal, and exposes the carbon fiber so as to be beneficial to the functionalization of the surface of the carbon fiber and the deposition of a coating in the subsequent roughening process. According to the method, the deoiled carbon fiber is subjected to roughening treatment, concentrated sulfuric acid and concentrated nitric acid are used as roughening liquid, compared with a traditional roughening process consisting of ammonium persulfate and dilute sulfuric acid, the roughening process of mixed strong acid can obviously improve the surface gully depth and surface roughness of the carbon fiber, and improve the number of oxygen-containing functional groups such as carboxyl and the like on the surface of the carbon fiber, so that the bonding strength between a coating and the carbon fiber is improved, and the uniformity of subsequent metal palladium catalytic cores distributed on the surface of the carbon fiber is improved. After the coarsening is finished, the coarsened carbon fiber is mixed with the colloidal palladium activation solution for activation, so that the colloidal palladium particles and a large number of oxygen-containing functional groups on the surface of the carbon fiber can generate adsorption, the colloidal palladium particles can be uniformly adsorbed on the surface of the carbon fiber, and the bonding strength between the colloidal palladium particles and the carbon fiber is high. And then, dispergating the activated carbon fiber to expose the elemental palladium particles in the micelle, so that the activated carbon fiber can play a role in catalysis in a deposition process, and finally depositing metal. The modified carbon fiber obtained by the method has uniform surface coating and high bonding strength between the coating and the carbon fiber, and has a positive effect on the subsequent preparation of the aluminum matrix composite with excellent comprehensive mechanical properties.

Further, compared with the traditional sensitization and activation two-step process flow, the one-step colloid palladium activation process greatly reduces the temperature required by the activation process and greatly shortens the time required by the activation process, so that the efficiency of the chemical plating process is remarkably improved (the activation temperature is 20-28 ℃, the time is 3-8 min; and the traditional sensitization and activation two-step process needs to be reacted for 50-70 min at 30-50 ℃).

The invention provides a modified carbon fiber reinforced aluminum matrix composite, which can effectively improve the wettability between an aluminum alloy matrix and carbon fibers by uniformly metallizing the surfaces of the carbon fibers, and the obtained modified carbon fiber reinforced aluminum matrix composite has good comprehensive mechanical properties.

The invention provides a preparation method of a modified carbon fiber reinforced aluminum matrix composite, which is simple and easy to operate, can realize continuous and efficient preparation of the carbon fiber reinforced aluminum matrix composite, and has good application prospect in the aspect of industrial large-scale preparation.

Drawings

FIG. 1 is a surface topography of a carbon fiber with glue removed according to example 1;

FIG. 2 is a surface topography of a modified carbon fiber prepared in example 1;

FIG. 3 is a surface topography of a modified carbon fiber prepared in comparative example 1;

FIG. 4 is a surface topography of a modified carbon fiber prepared in comparative example 2;

FIG. 5 is a surface topography of a modified carbon fiber prepared in comparative example 3;

FIG. 6 is a schematic view showing the structure of an apparatus used in example 2 for modifying a carbon fiber-reinforced aluminum-based composite material;

wherein, 1 is an aluminum alloy melt gate, 2 is an aluminum alloy backboard, 3 is modified carbon fiber, 4 is a covering layer, 5 is a roller, and 6 is a modified carbon fiber reinforced aluminum matrix composite;

FIG. 7 is an SEM image of a cross section of a modified carbon fiber reinforced aluminum matrix composite obtained in example 2.

Detailed Description

The invention provides a preparation method of modified carbon fibers, which comprises the following steps:

sequentially removing glue and oil from the carbon fiber to obtain oil-removed carbon fiber;

mixing the deoiled carbon fiber with a roughening solution, and then carrying out roughening treatment to obtain roughened carbon fiber; the coarsening liquid comprises: 180-220 mL/L of concentrated nitric acid, 180-220 mL/L of concentrated sulfuric acid and the balance of water;

mixing the coarsened carbon fiber with a colloidal palladium activation solution, and activating to obtain activated carbon fiber; the preparation raw materials of the colloidal palladium activating solution comprise: 0.3-0.7 g/L of palladium chloride, 30-40 g/L of stannous chloride, 40-60 mL/L of concentrated hydrochloric acid, 150-200 g/L of sodium chloride, 5-15 g/L of metallic tin and the balance of water;

mixing the activated carbon fibers with a dispergation solution, and dispergating to obtain dispergated carbon fibers;

and immersing the dispergated carbon fiber into metal deposition liquid for metal deposition to obtain the modified carbon fiber.

In the present invention, the starting materials used are all commercially available products well known in the art, unless otherwise specified.

The invention carries out degumming on the carbon fiber to obtain the degumming carbon fiber. The carbon fiber is not particularly limited in the present invention, and commercially available carbon fibers known in the art may be used. In the embodiment of the invention, the diameter of the carbon fiber is 6-8 μm. In the invention, the photoresist stripping process is preferably as follows: putting the carbon fiber into acetone, and carrying out ultrasonic treatment at 20-30 ℃ for 30-40 min. The method has no special requirement on the dosage of the acetone, and can completely immerse the carbon fiber. The invention has no special requirement on the power of the ultrasound, and the ultrasound power which is well known in the field can be adopted. The commercially available carbon fiber surface can wrap the one deck and leave factory and glue and protect its surface, is unfavorable for the later stage to carry out the deposit of surface coarsening and cladding material, and this glue film can take place fast decomposition and accompany with gas under high temperature environment simultaneously, is unfavorable for the complex process between later stage carbon fiber and aluminum alloy matrix. The protective glue on the surface of the carbon fiber can be removed by removing the glue, so that coarsening and direct contact between the surface of the carbon fiber and metal deposition liquid are facilitated, and gas generation can be avoided in the composite process.

After the photoresist is removed, deionized water is preferably adopted to wash the fibers subjected to photoresist removal treatment for 2-3 times, so that the photoresist-removed carbon fibers are obtained.

After the degumming carbon fiber is obtained, the invention removes oil from the degumming carbon fiber to obtain the oil-removed carbon fiber. In the invention, the deoiling liquid preferably comprises 50-70 g/L of sodium hydroxide, 10-30 g/L of sodium carbonate, 30-50 g/L of sodium phosphate and the balance of water; more preferably, the sodium hydroxide solution comprises 60g/L of sodium hydroxide, 20g/L of sodium carbonate, 40g/L of sodium phosphate and the balance of water. In the present invention, the oil removing process is preferably: and putting the degumming carbon fiber into degreasing liquid, and performing ultrasonic treatment for 20-40 min at the temperature of 60-80 ℃. The method has no special requirement on the dosage of the degreasing liquid, and can completely immerse the degumming carbon fiber. The invention has no special requirement on the power of the ultrasound, and the ultrasound power which is well known in the field can be adopted. The method further cleans the surface of the carbon fiber by degreasing, so that the carbon fiber is exposed, and the functionalization of the surface of the carbon fiber and the deposition of a coating in the subsequent roughening process are facilitated.

After the oil removal, the invention preferably further comprises the step of washing the fiber subjected to the oil removal treatment for 2-3 times by using deionized water to obtain the oil-removed carbon fiber.

After the deoiled carbon fiber is obtained, the deoiled carbon fiber is mixed with a roughening solution and then roughened to obtain the roughened carbon fiber.

In the present invention, the roughening liquid includes: 180-220 mL/L of concentrated nitric acid, 180-220 mL/L of concentrated sulfuric acid and the balance of water; preferably, the concentrated nitric acid solution comprises 190-210 mL/L concentrated sulfuric acid and 190-210 mL/L concentrated sulfuric acid, and the balance of water; more preferably, the nitric acid solution comprises 200mL/L concentrated nitric acid, 200mL/L concentrated sulfuric acid and the balance of water. In the invention, the mass fraction of the concentrated nitric acid is preferably 65.0%; the mass fraction of the concentrated sulfuric acid is preferably 98.3%.

The method has no special requirement on the dosage of the roughening solution, and can completely immerse the deoiled carbon fiber. The present invention does not require any special mixing procedure, and the mixing procedure known in the art can be adopted.

In the invention, the temperature of the roughening treatment is preferably 30-50 ℃, more preferably 35-45 ℃, and most preferably 40 ℃; the time is preferably 10 to 20min, and more preferably 15 min. In the present invention, the roughening treatment is preferably performed under ultrasonic conditions, and the present invention has no particular requirement on the power of the ultrasonic treatment, and the ultrasonic power well known in the art can be used. Compared with the traditional roughening process consisting of ammonium persulfate and dilute sulfuric acid, the roughening process of the mixed strong acid can obviously improve the depth of gully and the surface roughness of the surface of the carbon fiber and improve the number of oxygen-containing functional groups such as carboxyl and the like on the surface of the carbon fiber, thereby improving the bonding strength between a coating and the carbon fiber and simultaneously improving the uniformity of the subsequent metal palladium catalytic core on the surface of the carbon fiber.

After the roughening treatment is completed, the invention preferably further comprises the step of washing the roughened fiber for 2-3 times by using deionized water to obtain the roughened carbon fiber.

After the coarsened carbon fiber is obtained, the coarsened carbon fiber is mixed with the colloidal palladium activation solution for activation to obtain the activated carbon fiber.

In the invention, the raw materials for preparing the colloidal palladium activation solution comprise: 0.3-0.7 g/L of palladium chloride, 30-40 g/L of stannous chloride, 40-60 mL/L of concentrated hydrochloric acid, 150-200 g/L of sodium chloride, 5-15 g/L of metallic tin and the balance of water, and preferably comprises the following components: 0.5g/L of palladium chloride, 35g/L of stannous chloride, 50mL/L of concentrated hydrochloric acid, 178g/L of sodium chloride, 10g/L of metallic tin and the balance of water; in the present invention, the mass fraction of the concentrated hydrochloric acid is preferably 36.0%.

In the present invention, the preparation method of the colloidal palladium activation solution preferably includes the steps of: dissolving palladium chloride in concentrated hydrochloric acid to obtain a solution A; dissolving stannous chloride and sodium chloride in part of deionized water, and adding metallic tin to obtain feed liquid B; and adding the solution A into the feed liquid B, stirring and adding water to a target amount.

The preparation process of the invention generates colloidal palladium through ion reaction, and the specific ion reaction equation is as follows: pd²⁺+2Sn²⁺→[PdSn₂]⁶⁺；[PdSn₂]⁶⁺→Pd⁰+Sn²⁺+Sn⁴⁺. Wherein the micelle surrounding the carbon fiber is generated by hydrolysis of 2-valent tin ions, that is, the external component of the micelle is mainly Sn (OH)₂. The metal tin in the colloidal palladium activating solution has the function of preventing the 2-valent tin ions in the activating solution from being oxidized into 4-valent tin ions to destroy the stability of the activating solution when exposed to air. The invention has no special requirement on the dosage of partial water, and the dosage is preferably half of the total amount of the water in the colloidal palladium activating solution. The invention has no special requirement on the stirring rotating speed and does not cause liquid splashing.

The invention has no special requirement on the mixing process of the coarsened carbon fiber and the colloidal palladium activating solution, and the mixing process known in the field is adopted. The method has no special requirement on the dosage of the colloidal palladium activating solution, and can completely immerse the coarsened carbon fiber. In the invention, the activation temperature is preferably 20-28 ℃, and the activation time is preferably 3-8 min. In the activation process, the colloidal palladium particles and a large number of oxygen-containing functional groups on the surface of the carbon fiber generate adsorption, so that the colloidal palladium particles can be uniformly adsorbed on the surface of the carbon fiber, and the bonding strength between the colloidal palladium particles and the carbon fiber is high.

Compared with the traditional sensitization and activation two-step process flow, the method adopts the one-step colloidal palladium activation process to greatly reduce the temperature required by the activation process and greatly shorten the time required by the activation process, thereby obviously improving the efficiency of the chemical plating process (the traditional sensitization and activation two-step process needs to be reacted for 50-70 min at 30-50 ℃).

After the activation is completed, the method preferably further comprises the step of washing the activated fiber for 2-3 times by using deionized water to obtain the activated carbon fiber.

After the activated carbon fiber is obtained, the activated carbon fiber is mixed with the dispergation solution for dispergation, and the dispergation carbon fiber is obtained. In the present invention, the composition of the peptizing solution is preferably: 80-120 mL/L of concentrated hydrochloric acid and the balance of water; more preferably: 90-110 mL/L of concentrated hydrochloric acid and the balance of water. In the invention, the mass fraction of the concentrated hydrochloric acid is 36.0%.

The invention has no special requirement on the mixing mode of the activated carbon fiber and the peptizing solution, and the mixing process well known in the field is adopted. The invention has no special requirement on the dosage of the degumming solution, and can completely immerse the activated carbon fiber.

In the invention, the degumming temperature is preferably 30-50 ℃, and the time is preferably 2-5 min. In the dispergation process, the hydrochloric acid reacts Sn (OH)₂And consuming the palladium particles to expose the elemental palladium particles in the micelle, so that the palladium particles can play a catalytic role in the deposition process.

After the dispergation is finished, the obtained fiber is preferably washed for 2-3 times by using deionized water, so that the dispergation carbon fiber is obtained.

After the dispergated carbon fiber is obtained, the dispergated carbon fiber is immersed into metal deposition liquid for metal deposition, and the modified carbon fiber is obtained.

In the present invention, the metal deposition liquid preferably includes: 15-25 g/L nickel sulfate, 15-25 g/L sodium hypophosphite, 15-25 mL/L lactic acid and the balance of water; more preferably, it comprises: 20g/L of nickel sulfate, 20g/L of sodium hypophosphite, 20mL/L of lactic acid and the balance of water; the pH value of the metal deposition liquid is preferably 3.5-4.5.

In the invention, the temperature of metal deposition is preferably 50-70 ℃, and more preferably 60 ℃; the time is preferably 20-40 min, and more preferably 30 min.

In the deposition process of the present invention, palladium is used as a catalyst to promote Ni²⁺And H₂PO₂ ^-Oxidation-reduction reaction takes placeIn which Ni is²⁺The palladium catalyst is uniformly distributed on the surface of the carbon fiber, so that the deposition sites of Ni are promoted to be more uniform, and a layer of uniform metal (Ni) coating is deposited on the surface of the carbon fiber to obtain the modified carbon fiber.

After the deposition is finished, the method preferably further comprises the step of cleaning the deposited fibers for 2-3 times by using deionized water to obtain the modified carbon fibers.

The invention provides the modified carbon fiber prepared by the preparation method in the scheme. In the invention, the modified carbon fiber comprises carbon fiber and a metal coating attached to the surface of the carbon fiber; the thickness of the metal coating is preferably 1-3 μm. The metal coating in the modified carbon fiber is uniformly distributed (the standard deviation of the coating thickness is as low as 0.05 mu m), and in the preparation process, concentrated sulfuric acid and concentrated nitric acid are used as roughening liquid, so that compared with the traditional roughening process consisting of ammonium persulfate and dilute sulfuric acid, the roughening process of mixed strong acid can obviously improve the surface gully depth and surface roughness of the carbon fiber, further improve the bonding strength between the coating and the carbon fiber, and is favorable for improving the comprehensive mechanical property of the carbon fiber reinforced aluminum-based composite material.

The invention provides a modified carbon fiber reinforced aluminum matrix composite, which comprises the modified carbon fiber and an aluminum alloy matrix in the scheme; the aluminum alloy matrix wraps the modified carbon fibers and is soaked among the modified carbon fibers. The composition of the aluminum alloy matrix is not particularly required in the present invention, and any aluminum alloy known in the art may be used. In the present invention, the aluminum alloy matrix preferably contains Mg, preferably in an amount of < 5 wt.%. In the invention, the volume percentage content of the modified carbon fibers in the modified carbon fiber reinforced aluminum matrix composite is preferably 1-5%, and more preferably 2-4%. In the invention, the shape of the modified carbon fiber reinforced aluminum matrix composite is preferably a plate, and the thickness of the plate is preferably 10-20 mm.

The modified carbon fiber reinforced aluminum-based composite material adopts the carbon fiber which is subjected to metal surface modification as a reinforcing phase and has good wettability with an aluminum alloy matrix, in the invention, the wettability between an aluminum alloy melt and the carbon fiber can be effectively improved through surface metallization of the carbon fiber, so that capillary pressure of the melt in the infiltration process becomes infiltration power, and the infiltration process is changed from a physical filling process when the original carbon fiber is used into a spontaneous infiltration process. Meanwhile, the uniformity of the coating and the bonding strength between the coating and the carbon fibers can be improved, so that the stress concentration of an Al-coating metal interface and the rapid failure of a carbon fiber-matrix interface caused by the interface bonding strength can be effectively improved, and the tensile strength of the carbon fiber reinforced aluminum matrix composite material is improved.

The invention provides a preparation method of the modified carbon fiber reinforced aluminum matrix composite material, which comprises the following steps:

preheating the aluminum alloy back plate to obtain a preheated back plate;

preheating the modified carbon fiber to obtain preheated modified carbon fiber;

and laying the preheated modified carbon fibers on the upper surface of the preheating back plate, then pouring an aluminum alloy melt on the surface of the laid preheated modified carbon fibers, completely covering the modified carbon fibers, and rolling after the covering layer is solidified into a semi-solid state to obtain the modified carbon fiber reinforced aluminum-based composite material.

According to the invention, the aluminum alloy back plate is preheated to obtain the preheated back plate. In the invention, the material of the aluminum alloy back plate corresponds to the material of the aluminum alloy matrix in the modified carbon fiber reinforced aluminum matrix composite material in the scheme. In the invention, the thickness of the aluminum alloy back plate is preferably 5-10 mm. According to the invention, the surface cleaning and polishing treatment is preferably carried out on the aluminum alloy back plate, and then the preheating is carried out. The present invention does not require any particular process for the surface cleaning and polishing treatment, and may be carried out by any process known in the art for cleaning and polishing surfaces. In the present invention, the preheating is preferably performed in a heat treatment furnace; the preheating temperature is preferably 480-520 ℃, and more preferably 490-510 ℃; the time is preferably 20 to 40min, and more preferably 25 to 35 min.

The invention preheats the modified carbon fiber to obtain the preheated modified carbon fiber. In the invention, the preheating temperature of the modified carbon fiber is preferably 180-220 ℃, and more preferably 190-210 ℃; the time is preferably 20 to 40min, and more preferably 25 to 35 min. In the present invention, the preheating of the modified carbon fiber is preferably performed in a drying oven. In the invention, the modified carbon fiber is preferably preheated in the form of fiber bundles during preheating, so as to facilitate subsequent laying on the surface of the preheated back plate. The number of the fibers in the fiber bundle is not particularly required, and in the embodiment of the invention, the number of the carbon fibers in the fiber bundle is 3000.

The invention preheats the back plate and the modified carbon fiber, so that the aluminum alloy melt after casting can not be rapidly solidified, thereby keeping the semi-solid state in the rolling process.

After the preheating back plate and the preheating modified carbon fibers are obtained, the preheating modified carbon fibers are laid on the upper surface of the preheating back plate, then an aluminum alloy melt is poured on the surface of the laid preheating modified carbon fibers and the modified carbon fibers are completely covered, and after the covering layer is solidified into a semi-solid state, rolling is carried out, so that the modified carbon fiber reinforced aluminum matrix composite is obtained.

The invention has no special requirement on the laying thickness of the preheated modified carbon fiber and is determined according to the volume fraction of the modified carbon fiber in the composite material. According to the invention, the preheating modified carbon fibers are preferably uniformly paved on the whole upper surface of the preheating back plate.

In the invention, the components of the aluminum alloy melt are consistent with those of the aluminum alloy back plate, and both correspond to the components of the aluminum alloy matrix in the modified carbon fiber reinforced aluminum matrix composite material in the scheme. In the present invention, the preparation process of the aluminum alloy melt preferably comprises: smelting industrial pure aluminum by adopting a high-frequency induction furnace, heating to 720 +/-5 ℃, and heating and smelting for 5-15 min; after the aluminum alloy is completely melted, alloy elements are added according to the design components, and the mixture is uniformly stirred by a graphite rod to obtain the aluminum alloy melt.

The invention has no special requirements on the casting process of the aluminum alloy melt, and the casting process known in the field can be adopted. In the invention, the thickness of the covering layer is preferably 10-15 mm. In the invention, the aluminum alloy melt can be solidified into a semi-solid state after being poured for 1-3 min.

In the invention, the rolling is preferably carried out by adopting double rollers, the distance between the rollers is preferably 10-20 mm, and the rotating speed of the rollers is preferably 2-5 rad/min.

In the rolling process, the aluminum alloy melt infiltrates among the carbon fibers under the action of pressure, and finally the modified carbon fibers are wrapped by the aluminum alloy back plate and the aluminum alloy melt together to form the modified carbon fiber reinforced aluminum-based composite material.

After the rolling is completed, the invention preferably further comprises cooling the rolled plate, and the cooling process is not particularly required by the invention and can be realized by adopting a cooling process well known in the field.

In order to facilitate the technical solutions of the present application to be more clearly understood by those skilled in the art, a method for preparing the modified carbon fiber reinforced aluminum matrix composite of the present invention will now be described with reference to fig. 6. Preheating an aluminum alloy back plate 2 to obtain a preheated back plate; preheating the modified carbon fiber 3 to obtain preheated modified carbon fiber; and laying the preheated modified carbon fibers on the upper surface of the preheating back plate, then pouring an aluminum alloy melt on the surface of the laid preheated modified carbon fibers and completely covering the modified carbon fibers, and rolling by using a roller 5 after the covering layer 4 is solidified into a semi-solid state to obtain the modified carbon fiber reinforced aluminum-based composite material 6. The aluminum alloy melt is poured through an aluminum alloy melt pouring gate 1.

The modified carbon fiber and the preparation method thereof, and the modified carbon fiber reinforced aluminum matrix composite and the preparation method thereof provided by the present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.