CN102009239B - Connection method used for carbon based materials and products thereof - Google Patents

Abstract

The invention discloses a connection method for carbon-based materials and their products (including C/C composite materials, graphite and C/C aircraft brake discs, etc.), mainly used for C/C composite materials with complex shapes or large volumes Preparation and repair of parts, preparation and repair of graphite parts with complex shapes or large volumes, and repair of C/C aircraft brake discs. The connection method is to place the Co-Zr solder compact between two carbon-based materials or C/C aircraft brake disc connection surfaces for connection, through the pretreatment of carbon-based materials and C/C aircraft brake discs; solder The preparation of the solder compact; place the solder compact on the connection end surface of the pretreated carbon-based material or C/C aircraft brake disc material, apply pressure, heat, and finally cool to room temperature with the furnace, take it out, and the carbon-based material or C/C The connection of the aircraft brake disc is completed. The connection method provided by the invention has the advantages of simple process, safety and reliability, high connection strength and low cost, and the economic benefit is very considerable no matter it is used for the preparation or repair of parts.

Description

A connection method for carbon-based materials and products thereof

technical field

The invention belongs to the technical field of carbon-based materials, and relates to a carbon/carbon composite material (that is, a carbon fiber reinforced carbon composite material, represented by C/C), graphite and a connection method of a C/C aircraft brake disc, specifically, a An effective joining method for preparing and repairing C/C composite parts, graphite parts and C/C aircraft brake discs.

Background technique

C/C composite materials have the characteristics of high specific strength, high specific stiffness, excellent ablation resistance and friction performance, good thermal shock resistance, low creep and high strength retention at high temperature, and are widely used in the aerospace industry . Graphite materials, especially high-strength graphite, have the characteristics of light weight, high specific strength, heat resistance, corrosion resistance, good electrical and thermal conductivity, and excellent thermal shock resistance, and are widely used in the aerospace industry and the nuclear industry.

The connection technologies currently used for C/C composite materials and graphite materials include mechanical connection, brazing method, diffusion connection method, and reaction forming connection method using polymer materials as a connecting agent.

(1) Mechanical connection

Mechanical joints are mainly secured with bolts made of refractory metal or carbon/carbon composites themselves, but such joints have poor shear and compressive strength, especially where stress concentrations occur around the bolt or rivet holes.

(2) Brazing method

This connection method is a relatively mature method for connecting C/C composite materials and graphite materials. The solders used include Ag-Cu-Ti, Al, Mg ₂ Si and glass. When Ag-Cu-Ti and Al solders are used, the working temperature of the joint is not high, generally below 500 °C. Unable to meet the needs of high temperature applications of joints in the aerospace industry. When using Mg ₂ Si solder to braze three-dimensional C/C composite materials in argon gas, the temperature is 1693K, and the holding time is 45min, the shear strength of the joint is low, about 5MPa. However, the interfacial bonding of C/C composites brazed with glass solder is poor. Using Ti-Cr and other solders to braze graphite at high temperature, the joint strength is not high.

(3) Diffusion connection method

The solid-state diffusion bonding method heats and pressurizes the base metal to be welded at the same time, so that a small amount of plastic deformation occurs at the joint to form a close contact, and then atomic diffusion occurs to achieve the connection. Generally, it is divided into direct diffusion bonding method and indirect diffusion bonding method. For the solid-state diffusion connection of C/C composites, the connection pressure will cause damage to the fibers of the composite and the interface between the fiber and the matrix. In addition, the diffusion bonding process needs to apply high pressure in a high temperature state, so the process is complicated, the process cycle is long, and the equipment cost and process cost are high.

(4) Reaction forming connection method using polymer material as linking agent

This connection method mainly uses organic resin and powder additives as raw materials, and connects C/C composite materials and graphite materials through low-temperature curing and high-temperature treatment. This connection method is simple in process and low in cost, and has certain advantages. However, due to the gas generated during the cross-linking and cracking process of polymer materials, the connection layer is porous and the connection strength is low. In addition, this method is also likely to cause environmental pollution, thus limiting its engineering application.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention provides a connection method for carbon-based materials and products thereof, the carbon-based materials include C/C composite materials and graphite, and the carbon-based materials products include C /C aircraft brake disc, the connection method can be used for the connection between the same or different carbon-based materials, and can also be used for the same or different carbon-based material products such as C/C aircraft brake discs Repair joints, which use Co-Zr solder to join C/C composites, graphite, and C/C aircraft brake discs.

The connection method for carbon-based materials and products thereof of the present invention is to place Co-Zr solder between the connecting end faces of C/C composite materials, graphite or C/C aircraft brake discs for connection, and the connection process is:

(A) Pretreatment of the joining surface;

Grind and polish the connecting end faces of C/C composite material, graphite and C/C aircraft brake disc, clean them with ultrasonic waves for 15-30 minutes, then dry them for use;

(B) Preparation of solder;

Select micron-sized Co powder and Zr powder with a particle size of 5-90 μm, mix Co powder and Zr powder, and the mass percentage of Zr powder is 2%-8%; mix the mixed powder in alcohol with ultrasonic vibration 20-30min. In order to avoid stratification due to different powder densities, it should be stirred at any time during the mixing process. After the mixed powder is dry, it is poured into a mortar and ground for 20-30 minutes to ensure that the powder is mixed evenly. Then a certain amount of solder is weighed and cold-pressed on a tablet press to obtain a solder compact.

(C) connection process;

Place the solder compact obtained in the above (B) on the connection end surface of the C/C composite material, graphite or C/C aircraft brake disc after the treatment in (A), or directly distribute the mixed powder on the large parts And the connecting end surface of the brake disc; then put the two connecting end surfaces into a vacuum furnace, apply a pressure of 5-20kPa, the heating process is as follows: firstly, the temperature is raised to 800-1000°C at a rate of 15-20°C/min, and then Raise the temperature at a rate of 6-12°C/min to 1200-1450°C, keep it warm for 3-10 minutes, then cool down to room temperature with the furnace, and take it out. The connection of carbon-based materials and their products is completed.

The solder layer obtained after connecting by the above method is uniform and dense, forming a good metallurgical bond and mechanical engagement with the base metal.

The interface is mainly composed of Co, C and ZrC.

The method for connecting carbon-based materials and products thereof can be used to prepare C/C parts with complex shapes and large C/C parts, and can also be used to prepare graphite parts with complex shapes and large graphite parts.

The connection method of the carbon-based material and its products can be used for the repair of C/C parts, and can also be used for the repair of graphite parts.

The connection method of the carbon-based material and its products can be used for the repair of C/C aircraft brake discs, including "two-in-one" (that is, two brake discs that have been thinned into one piece) and "three-in-one" ( That is, three brake discs that have been thinned are connected into one piece), etc.

The advantages of the effective connection method for carbon-based materials and products thereof of the present invention are:

(1) The joint obtained by the present invention has high strength, which can reach at least 87.8% of the strength of the base metal, and is suitable for high temperature applications.

(2) The connection method has the characteristics of simple operation and low connection pressure. On the one hand, it avoids the damage of the fiber of the composite material and the interface between the fiber and the matrix due to the high connection pressure; on the other hand, the equipment required for the connection Simple, easy to implement, and low process cost.

(3) The solder powder materials used in this connection method are commercially available, and the connection cost of this method is low.

Description of drawings

Figure 1 is a superimposed schematic diagram of C/C composite material and solder compact;

Figure 2a is the micromorphology of the connector interface area of the C/C composite material connected by Co-Zr solder;

Figure 2b is a spectrum of EDS line analysis along the straight line in Figure 2a;

Fig. 3 is the XRD spectrum of the connector interface region adopting Co-Zr solder to connect the C/C composite material;

Figure 4a is the micromorphology of the connector interface region of the graphite material connected by Co-Zr solder;

Figure 4b is a spectrum of EDS line analysis along the straight line in Figure 4a;

Fig. 5 is an XRD spectrum of the interface region of the connector connecting the graphite material with Co-Zr solder.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

The invention is a connection method for carbon-based materials and its products C/C aircraft brake discs. Co-Zr solder is placed between the connection end faces of two C/C composite materials, or between two pieces of graphite materials. Connect between the end faces, or connect the end faces of two C/C aircraft brake discs to realize the connection of two C/C composite materials, or the connection of two graphite materials, or two C/C aircraft brake discs The connection, the connection process is as follows:

(A) Pretreatment of the connecting end faces of carbon-based materials and their products;

Grind and polish the connecting end faces of carbon-based materials and their products, clean them with ultrasonic waves for 15-30 minutes, and then dry them for use;

(B) Preparation of solder;

Select Co powder and Zr powder with micron particle size, mix Co powder and Zr powder, wherein the mass percentage of Zr powder is 2%-8%; mix the mixed powder in alcohol with ultrasonic vibration for 20-30min. In order to avoid stratification due to different powder densities, it should be stirred at any time during the mixing process. After the mixed powder is dry, it is poured into a mortar and ground for 20-30 minutes to ensure that the powder is mixed evenly. Then take a part of the solder, and cold press it on a tablet press to obtain a solder compact. The particle diameters of the Co powder and the Zr powder are both 5-90 μm.

(C) connection process;

Place the solder compact prepared in (B) above on the connection end surface treated by (A), or directly distribute the mixed powder on the connection end surface, and then superimpose the two connection end surfaces to be connected and put them in a vacuum In the furnace, a pressure of 5-20kPa is applied, and the heating process is as follows: firstly, the temperature is raised to 800-1000°C at a rate of 15-20°C/min, and then the temperature is raised to 1200-1450°C at a rate of 6-12°C/min, and the temperature is kept for 3-10min , then cool to room temperature with the furnace, and take it out. The connection of carbon-based materials or products thereof is completed.

The following examples will further illustrate the present invention. The examples are only used to illustrate that the connection process of the present invention is feasible, and are not intended to limit the scope of protection of the present invention.

Example 1 The method provided by the present invention is used to connect C/C composite materials.

In the preparation process of C/C composite parts with complex shapes, due to the complex preparation process and high cost of C/C composite materials, it is difficult to prepare C/C composite parts with complex shapes by one-time forming method, so it is necessary to C/C composite materials with simple shapes are connected to form C/C composite parts with complex shapes. The specific connection process of C/C composite materials is as follows:

(A) Pretreatment of C/C composite materials;

Grind and polish the connecting end face of the C/C composite material, clean it with ultrasonic waves for 30 minutes, then dry it for use;

(B) Preparation of solder;

Select Co powder and Zr powder with a particle size of 5 μm, mix Co powder and Zr powder, wherein the mass percentage of Zr powder is 2%, and mix the mixed powder in alcohol with ultrasonic vibration for 30 minutes. In order to avoid stratification due to different powder densities, it should be stirred at any time during the mixing process. After the mixed powder is dry, it is poured into a mortar and ground for 20 minutes to ensure that the powder is mixed evenly. Then the solder is weighed and cold-pressed on a tablet press to obtain a solder compact.

(C) connection process;

Place the solder compact prepared in (B) above on the connection end surface of the C/C composite material treated by (A), and then superimpose the two connection end surfaces that need to be connected, as shown in Figure 1. After superposition, place Put it into a vacuum furnace and apply a pressure of 20kPa. The heating process is as follows: firstly, the temperature is raised to 800°C at a rate of 15°C/min, then to 1200°C at a rate of 12°C/min, kept for 3 minutes, then cooled to room temperature with the furnace, and taken out. The connection of the C/C composite is complete.

Embodiment 2 applies the connection method provided by the present invention to repair the C/C aircraft brake disc

After the C/C aircraft brake disc has been used for many times, the thickness of the brake disc can no longer meet the requirements of the brake structure. It is necessary to connect two or three brake discs that have been thinned (referred to as "two-in-one" and "Three-in-one") was put into use again. Because the preparation process of the C/C aircraft brake disc is complicated, the cost is high, and the price is expensive, so the economic benefits of this repair technology are very considerable. The brake disc is connected by the following methods:

(A) Pretreatment of brake discs;

Grind and polish the connecting end surface of the C/C brake disc, clean it with ultrasonic waves for 30 minutes, then dry it for use;

(B) Preparation of solder;

Select Co powder and Zr powder with a particle size of 80 μm, mix Co powder and Zr powder, wherein the mass percentage of Zr powder is 8%; mix the mixed powder in alcohol with ultrasonic vibration for 20 minutes. In order to avoid stratification due to different powder densities, it should be stirred at any time during the mixing process. After the mixed powder is dry, it is poured into a mortar and ground for 30 minutes to ensure that the powder is evenly mixed.

(C) connection process;

Arrange the mixed powder prepared in the above (B) on the connection end surface of the C/C aircraft brake disc treated by (A) in the form of direct powder distribution, and then put the two connection end surfaces into a vacuum furnace after being superimposed, and apply The pressure is 20kPa, the heating process is as follows: firstly, the temperature is raised to 1000°C at a rate of 20°C/min, then to 1450°C at a rate of 6°C/min, kept for 10 minutes, then cooled to room temperature with the furnace, and taken out. The connection of the C/C aircraft brake disc is completed.

According to Examples 1 and 2, the Co-Zr solder can form a solder layer with good performance during the connection process, and the solder and the base material undergo interfacial diffusion and interfacial reaction, and a connector with high connection strength can be obtained. The maximum shear strength of the connector reaches 17.0MPa, which is 92.4% of the strength of the base material of the C/C composite material. The microstructure and composition analysis show that at the interface between the C/C composite material and the solder, the elements in the base metal and the solder have interdiffused, forming a good metallurgical bond and mechanical occlusion at the interface, and the solder layer is uniform and dense. The active element Zr in the solder reacts with the C/C composite to form ZrC.

Accompanying drawing 2 is the SEM scan photo and the EDS line analysis diagram of the connector interface area of the connector that adopts Co-Zr solder to connect the C/C composite material. It can be seen from the scanning photo that the solder and the C/C composite material form a good interface bond, and the solder layer is uniform and dense. According to the EDS line analysis spectrum, it can be seen that the C element in the C/C composite material interdiffused with the Co and Zr elements in the solder.

Accompanying drawing 3 is the XRD spectrum of the connector interface region of the connectors using Co-Zr solder to connect C/C composite materials. From this map, it can be seen that the interfacial region is mainly composed of C, Co, and ZrC. Among them, C and Co come from the base metal and solder, respectively. The figure shows that during the bonding process, Zr, which is a strong carbide-forming element and highly active at the interface, undergoes an interfacial reaction with C in the C/C composite to form ZrC. Due to the low Zr content of the solder itself, the amount of the interface reaction product ZrC is small, and the mass percentage in the phase existing in the interface area is low, and the intensity of the diffraction peak in the spectrum is weak.

Embodiment 3 Application of the connection method provided by the present invention to connect graphite materials

In the preparation process of graphite parts with complex shapes or structures, due to the brittleness of graphite, it is difficult to prepare graphite parts with complex shapes or structures by one-time forming method, so it is necessary to connect graphite materials with simple shapes to form complex shapes or structures. Graphite parts, the specific connection method is as follows:

(A) pretreatment of graphite;

Grind and polish the connecting end face of graphite, clean it with ultrasonic waves for 15 minutes, then dry it and set it aside;

(B) Preparation of solder

Select Co powder and Zr powder with a particle size of 90 μm, mix Co powder and Zr powder, wherein the mass percentage of Zr powder is 8%; mix the mixed powder in alcohol with ultrasonic vibration for 20 minutes. In order to avoid stratification due to different powder densities, it should be stirred at any time during the mixing process. After the mixed powder is dry, it is poured into a mortar and ground for 30 minutes to ensure that the powder is evenly mixed. Then the above mixed powder is weighed and cold-pressed on a tablet machine to obtain a solder compact.

(C) connection process;

The solder compact obtained in the above step (B) is placed on the connection end face of the graphite processed by the step (A), and then the two connection end faces to be connected are superimposed and put into a vacuum furnace, and a pressure of 5 kPa is applied. The heating process is as follows: firstly, the temperature is raised to 800°C at a rate of 20°C/min, then to 1450°C at a rate of 12°C/min, kept for 10 minutes, then cooled to room temperature with the furnace, taken out, and the connection of graphite is completed.

According to Example 3, the Co-Zr solder can form a solder layer with good performance during the connection process, and interfacial diffusion and interfacial reaction occur between the solder and the graphite base material, and a connector with high connection strength can be obtained. The maximum strength of the connecting piece is 87.8% of the strength of the graphite base material. The microstructure and composition analysis show that at the interface between graphite and solder, elements in graphite base material and solder have interdiffused, forming good metallurgical bonding and mechanical interlocking at the interface, and the solder layer is uniform and dense. The active element Zr in the solder reacts with graphite to form ZrC.

Accompanying drawing 4a, 4b are the SEM scan photo and the EDS line analysis spectrum of the interface area of the connector connecting the graphite using Co-Zr solder. It can be seen from the scanning photo that the solder and graphite form a good interface bond, and the solder layer is uniform and dense. According to the EDS line analysis spectrum, it can be seen that the C element in the graphite base material interdiffused with the Co and Zr elements in the solder.

Accompanying drawing 5 is the XRD spectrum of the connector interface area of the graphite connected by Co-Zr solder. From this map, it can be seen that the interfacial region is mainly composed of C, Co, and ZrC. Among them, C and Co come from the base metal and solder, respectively. This figure shows that during the bonding process, Zr, which is a strong carbide-forming element and very active at the interface, undergoes an interfacial reaction with graphite to form ZrC. Due to the low Zr content of the solder itself, the amount of the interface reaction product ZrC is small, and the mass percentage in the phase existing in the interface area is low, and the intensity of the diffraction peak in the spectrum is weak.

According to the above test results, it can be seen that during the connection process, at the interface between the carbon-based material and the solder, the elements in the base material and the solder undergo interdiffusion, forming a good metallurgical bond and mechanical occlusion at the interface, and the solder layer Uniform and dense. The active element Zr in the solder has an interfacial reaction with the carbon-based material to form ZrC, which promotes interfacial bonding, thus obtaining a higher connection strength.

Claims (10)

1. A connection method for carbon-based materials, characterized in that: the connection method is applicable to the connection between the same or heterogeneous carbon-based materials, specifically through the following connection process: (A) connection surface pretreatment; Grind and polish the connecting end surface of the carbon-based material, clean it with ultrasonic waves for 15-30 minutes, then dry it for use; (B) Preparation of solder, Select Co powder and Zr powder with a particle size of micron, mix Co powder and Zr powder, wherein the mass percentage of Zr powder is 2% to 8%; mix the mixed powder in alcohol with ultrasonic vibration for 20 to 30 minutes, Stir at any time during the mixing process; after the mixed powder is dry, pour it into a mortar and grind for 20-30 minutes to ensure that the powder is evenly mixed; (C) connection process, The mixed powder prepared in the above (B) is cold-pressed on a tablet machine to obtain a solder compact, and the solder compact is placed on the connection end surface treated by (A); or the mixed powder is directly distributed on the connection end surface ; Then put the two connected ends into a vacuum furnace and apply a pressure of 5-20kPa. The heating process is as follows: firstly, the temperature is raised to 800-1000°C at a rate of 15-20°C/min, and then at a rate of 6-12°C/min. Raise the temperature to 1200-1450°C, keep it warm for 3-10 minutes, then cool down to room temperature with the furnace, take it out, and the connection of carbon-based materials is completed. 2. The connection method for carbon-based materials according to claim 1, characterized in that: in the solder, the selected Co powder and Zr powder have a particle size of 5-90 μm. 3. The connection method for carbon-based materials according to claim 1, characterized in that: the solder layer formed after the connection is uniform and dense, and forms a good metallurgical bond and mechanical engagement with the base material. 4. The connection method for carbon-based materials according to claim 1, characterized in that the connection interface is mainly composed of Co, C and ZrC. 5. The connecting method for carbon-based materials according to claim 1, characterized in that it is used for preparing or repairing C/C composite parts. 6. The connecting method for carbon-based materials according to claim 1, characterized in that it is used for preparing or repairing graphite material parts. 7. The connection method for carbon-based materials according to claim 1, characterized in that: it is used for repairing C/C aircraft brake discs, including two brake discs that have been worn thin and connected into one piece, or three worn brake discs The thin brake discs are joined into one piece. 8. A connection method for carbon-based material products, characterized in that: the connection method is suitable for the connection between the same or different carbon-based material products, specifically through the following connection process: (A) connection surface pretreatment; Grind and polish the connection end surface of the carbon-based material product, clean it with ultrasonic waves for 15-30 minutes, then dry it for use; (B) Preparation of solder, Select Co powder and Zr powder with a particle size of micron, mix Co powder and Zr powder, wherein the mass percentage of Zr powder is 2% to 8%; mix the mixed powder in alcohol with ultrasonic vibration for 20 to 30 minutes, Stir at any time during the mixing process; after the mixed powder is dry, pour it into a mortar and grind for 20-30 minutes to ensure that the powder is evenly mixed; (C) connection process, The mixed powder prepared in the above (B) is cold-pressed on a tablet machine to obtain a solder compact, and the solder compact is placed on the connection end surface treated by (A); or the mixed powder is directly distributed on the connection end surface ; Then put the two connected ends into a vacuum furnace and apply a pressure of 5-20kPa. The heating process is as follows: firstly, the temperature is raised to 800-1000°C at a rate of 15-20°C/min, and then at a rate of 6-12°C/min. Raise the temperature to 1200-1450°C, keep it warm for 3-10 minutes, then cool down to room temperature with the furnace, take it out, and the connection of the carbon-based material product is completed. 9. A connection method for carbon-based material products according to claim 8, characterized in that: in the solder, the selected Co powder and Zr powder have a particle size of 5-90 μm. 10. A connection method for carbon-based material products according to claim 8, characterized in that: the connection interface is mainly composed of Co, C and ZrC.

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