阅读说明：本技术 一种max相陶瓷的连接方法 (MAX phase ceramic connection method ) 是由 张海斌 谭永强 钱达志 彭述明 李思功 薛佳祥 李锐 刘彤 于 2019-11-12 设计创作，主要内容包括：本发明涉及一种MAX相陶瓷的连接方法,属于陶瓷焊接领域。将石墨烯、碳纳米管等碳纳米材料与异丙醇混合制成浆料均匀涂覆在抛光后的MAX相陶瓷表面,两片MAX相陶瓷叠加后在1200°C~1400°C之间,真空度10<Sup>-2</Sup> Pa以上,2~5 MPa压力下焊接20 min即可实现任意两种MAX相陶瓷材料的无缝连接。通过该方法获得的陶瓷连接强度可达到母材强度的80%以上,而且该工艺适用于任意相同以及不同类型的MAX相陶瓷之间的连接。(The invention relates to a connection method of MAX phase ceramics, belonging to the field of ceramic welding, wherein carbon nano materials such as graphene and carbon nano tubes are mixed with isopropanol to prepare slurry, the slurry is uniformly coated on the surface of the MAX phase ceramics after polishing, two MAX phase ceramics are superposed and then are between 1200 ℃ and ~ 1400 ℃, and the vacuum degree is 10 ‑2 The seamless connection of any two MAX phase ceramic materials can be realized by welding for 20min under the pressure of 2 ~ 5MPa and the ceramic connection strength obtained by the method can reach more than 80% of the base material strength, and the process is suitable for the connection of MAX phase ceramics of any same and different types.)

1. A method for connecting MAX phase ceramics is characterized in that: the connection method of the MAX phase ceramics comprises the following steps:

step 1: slurry preparation

Selecting one of graphene and carbon nano tubes as an intermediate layer, and mixing the materials in a volume ratio of 1: 5, adding graphene or carbon nano tubes into an isopropanol solvent, and performing ultrasonic dispersion for 30min to obtain graphene or carbon nano tube slurry;

step 2: slurry coating

Processing any two MAX-phase ceramic blocks by utilizing linear cutting, grinding and polishing the surfaces, ultrasonically cleaning the MAX-phase ceramic blocks, uniformly coating uniformly dispersed graphene or carbon nanotube slurry on the surfaces of the MAX-phase ceramic blocks, and after drying, contacting the two surfaces coated with the graphene or carbon nanotube to form a MAX-phase ceramic group;

and step 3: high temperature vacuum welding

And (3) placing the MAX phase ceramic group in a vacuum sintering furnace for welding, and cooling after welding to obtain the MAX phase ceramic with uniform welding.

2. A method of joining MAX phase ceramics as claimed in claim 1 wherein in step 3, the welding pressure is 2 ~ 5MPa, the welding temperature is 1200 ~ 1400 ℃ and 1400 ℃, and the welding time is 20 ~ 40 min.

3. A method of joining MAX phase ceramics according to claim 1, characterised in that: the MAX phase ceramic includes any of 312-, 211-, 413-type structures.

4. A method of joining MAX phase ceramics according to claim 1, characterised in that: MAX phase ceramics is Ti₃SiC₂、Ti₃AlC₂、Ti₂AlC、Nb₂AlC、Cr₂AlC、Nb₄AlC₃Any two of the materials.

5. A method of joining MAX phase ceramics according to claim 1, characterised in that: in the step 1, the thickness of the graphene sheet is less than 100 nm.

6. A method of joining MAX phase ceramics according to claim 1, characterised in that: and (3) the wall thickness of the carbon nano tube in the step (1) is less than 20 nm.

7. The method for connecting MAX phase ceramics according to claim 1, wherein the mass per unit area of graphene or carbon nanotubes coated in step 2 is 5 ~ 10 mg/cm or less²。

Technical Field

The invention relates to a connection method of MAX phase ceramics, belonging to the field of ceramic welding.

Background

Mn +1AXn (MAX phase for short) ceramics are ternary carbon/nitride ceramics with a nano-layered structure, wherein M represents a transition metal element, A represents a carbon or nitrogen element, and n is generally 1 ~, wherein the MAX phase ceramics have the characteristics of ceramics and metals, such as high strength, high electric and thermal conductivity, corrosion resistance, oxidation resistance, excellent processability and the like.

M found so far_n+1AX_nMore than one hundred kinds of them are mainly divided into M₂AX (211 phase), M₃AX₂(312 phase) with M₄AX₃(413 phases) three types.

The connection of the MAX phase ceramic materials is always a difficult point of application, and related workers at home and abroad make primary attempts on the connection of the MAX phase ceramic materials. It has been found from published reports that the connection of MAX phase ceramics can be realized by using Al, Si and Ni as intermediate layers or by direct solid phase diffusion. Al foil is used as an intermediate layer, and Al atoms are diffused to the ceramic base material under the conditions of 1100-1500 DEG C₃SiC₂The connection of ceramics and the generation of high-temperature resistant Ti at the interface₃Si(Al)C₂The bending strength of the joint is 65% of that of the base material by solid solution. Based on the same principle, in Ti₃AlC₂Sputtering simple substance Si with the thickness of 4-10 mu m on the ceramic area to be welded, and pressing in a hot-pressing furnaceRealizing Ti under the pressure of 2-5MPa₃AlC₂Ceramic joining with interface formation of high temperature resistant Ti₃Si(Al)C₂The bending strength of the joint reaches 80% of that of the base material by solid solution. Ti of Lanzhou chemical and physical research institute of Chinese academy of sciences₃SiC₂Placing Ni foil in between, and introducing high-frequency pulse current to rapidly heat in vacuum environment under compression state, wherein the high-frequency pulse current can make Ti₃SiC₂Generating plasma state at the microcosmic contact point of Ni foil to make Ti₃SiC₂Rapidly react with Ni at high temperature to form Ti₃SiC₂A connecting layer therebetween, thereby realizing Ti₃SiC₂Welding between the ceramics themselves.

By utilizing the characteristic that Al atoms in parent metal at 1300 ℃ or above continuously migrate outwards along the layered structure, discontinuous Al is formed at the interface under the condition of low oxygen partial pressure₂O₃Layer of can realize Ti₃AlC₂-Ti₃AlC₂、Ti₂AlC-Ti₂No intermediate layer of AlC is diffusion bonded. The temperature rise is favorable for further outward migration and oxidation of the Al element, so that continuous Al is formed at the interface at 1400 DEG C₂O₃Layer due to Ti₃AlC₂、Ti₂AlC and Al₂O₃The thermal expansion coefficients of the joint are close, so that the residual stress generated by the joint is small, and the shear strength of the joint is improved.

Disclosure of Invention

The invention aims to provide a MAX phase ceramic connecting method which can realize the connection of any two MAX phase ceramics and obtain high connection strength.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a connection method of MAX phase ceramics is characterized by comprising the following steps:

step 1: slurry preparation

Selecting one of graphene and carbon nano tubes as an intermediate layer, and mixing the materials in a volume ratio of 1: 5, adding graphene or carbon nano tubes into an isopropanol solvent, and performing ultrasonic dispersion for 30min to obtain graphene or carbon nano tube slurry;

step 2: slurry coating

Processing any two MAX-phase ceramic blocks by utilizing linear cutting, grinding and polishing the surfaces, ultrasonically cleaning the MAX-phase ceramic blocks, uniformly coating uniformly dispersed graphene or carbon nanotube slurry on the surfaces of the MAX-phase ceramic blocks, and after drying, contacting the two surfaces coated with the graphene or carbon nanotube to form a MAX-phase ceramic group;

and step 3: high temperature vacuum welding

And (3) placing the MAX phase ceramic group in a vacuum sintering furnace for welding, and cooling after welding to obtain the MAX phase ceramic with uniform welding.

Preferably, in the step 3, the welding pressure is 2 ~ 5MPa, the welding temperature is 1200 ~ 1400 ℃ and 1400 ℃, and the welding time is 20 ~ 40 min.

Preferably, the MAX phase ceramic comprises any of 312, 211, 413 type structures.

Preferably, the MAX phase ceramic is Ti₃SiC₂、Ti₃AlC₂、Ti₂AlC、Nb₂AlC、Cr₂AlC、Nb₄AlC₃Any two of the materials.

Preferably, the thickness of the graphene sheet layer in step 1 is less than 100 nm.

Preferably, the wall thickness of the carbon nanotubes in step 1 is less than 20 nm.

Preferably, the mass per unit area of the graphene or the carbon nanotube coated in the step 2 is 5 ~ 10 mg/cm²

The invention has the advantages and beneficial effects that:

1. according to the method, the graphene is used as a connecting interlayer, and the seamless connection of the MAX-phase ceramics can be realized at a lower pressure and a lower temperature in a shorter time;

2. the method is suitable for the connection process of all MAX phase ceramic materials, and has strong applicability;

3. the MAX phase ceramic obtained by the method has high connection strength which can reach more than 80% of the strength of the base material.

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention. The technical solution of the present invention is further illustrated by the following specific examples.

A connection method of MAX phase ceramics utilizes carbon nano materials such as graphene and carbon nano tubes as an intermediate layer to realize connection of any MAX phase ceramics under certain pressure and temperature. The method comprises the following steps:

step 1: slurry preparation

According to the volume ratio of 1: 5, adding graphene or carbon nano tubes into an isopropanol solvent, and performing ultrasonic dispersion for 30min to obtain graphene or carbon nano tube slurry;

step 2: slurry coating

Any two MAX-phase ceramic blocks are processed by linear cutting, and the MAX-phase ceramic blocks are ground and polished on the surfaces; after the MAX-phase ceramic block is ultrasonically cleaned, uniformly coating the uniformly dispersed graphene or carbon nanotube slurry on the surface of the MAX-phase ceramic block, and after drying, contacting the two surfaces coated with the graphene or carbon nanotube to form a ceramic group;

and step 3: high temperature vacuum welding

And placing the MAX phase ceramic group to be welded in a vacuum sintering furnace, performing high-temperature welding for 20 ~ 40min under the conditions of certain pressure and certain temperature, and cooling after the welding is finished to obtain the MAX phase ceramic with uniform welding.

The carbon nano materials such as graphene and carbon nano tubes are selected as the intermediate layer mainly because the intermediate layer has high specific surface area and is easy to generate diffusion reaction with the matrix. In the step 1, isopropanol is used as a solvent, so that the carbon nano material is more favorably dispersed.

In a preferred embodiment, the certain pressure set in step 3 is 2 ~ 5MPa and the certain temperature is 1200 ~ 1400 ℃ during the high-temperature vacuum welding, the 2 ~ 5MPa pressure applied in the welding process is too high, which causes the MAX phase ceramic to deform at high temperature, and too low, which causes the connection strength to be reduced, the welding strength is low below 1200 ℃, and the elements of the MAX phase ceramic volatilize or decompose above 1400 ℃, and the connection time is too short, which causes the connection strength to be low, and the elements of the MAX phase ceramic volatilize due to too long time.

Further preferably, the MAX phase ceramic material comprises any of type 312, type 211, type 413, such as Ti₃SiC₂、Ti₃AlC₂、Ti₂AlC、Nb₂AlC、Cr₂AlC、Nb₄AlC₃And the like.

Further preferably, the graphene sheets in step 1 have a thickness of less than 100 nm. Too high a thickness of the graphene sheet layer may reduce the weld strength.

Further preferably, the wall thickness of the carbon nanotubes in step 1 is less than 20 nm. The welding strength is reduced by the excessive wall thickness of the carbon nanotube.

Further preferably, the mass per unit area of the graphene or the carbon nanotube coated in the step 2 is 5 ~ 10 mg/cm²。

Too much or too little graphene or carbon nanotubes coated may result in reduced connection strength.