阅读说明：本技术 一种壳核结构MXene@MAX复合触头增强相材料及其制备方法 (Shell-core structure MXene @ MAX composite contact reinforcing phase material and preparation method thereof ) 是由 丁健翔 孙正明 查余辉 黄培艳 张骁 王东 于 2019-09-12 设计创作，主要内容包括：本发明公开了一种壳核结构MXene@MAX复合触头增强相材料及其制备方法；所述MXene@MAX复合触头增强相材料为多维核壳结构,内核为MAX相材料,外壳为同内核MAX相材料对应的MXene材料；本发明同时公开了将上述MXene@MAX用于制备Ag/MXene@MAX复合触头材料及其制备方法,本发明所制备的MXene@MAX复合触头增强相材料,与Ag基体复合后,三维MAX起到支撑结构,二维MXene起到导电导热、增强与Ag基界面结合的作用,提高了Ag基电触头的密度、导电、导热和抗电弧侵蚀性能,且降低了电触头的表面温升、接触电阻以及材料损失率。(The invention discloses a shell-core structure MXene @ MAX composite contact enhanced phase material and a preparation method thereof; the MXene @ MAX composite contact reinforcing phase material is of a multi-dimensional core-shell structure, the inner core is a MAX phase material, and the shell is an MXene material corresponding to the MAX phase material of the inner core; the MXene @ MAX composite contact reinforcing phase material prepared by the method is compounded with an Ag matrix, the three-dimensional MAX plays a supporting structure, and the two-dimensional MXene plays a role in conducting electricity and heat, enhancing the combination with an Ag-based interface, so that the density, the electric conductivity, the heat conductivity and the arc erosion resistance of the Ag-based electrical contact are improved, and the surface temperature rise, the contact resistance and the material loss rate of the electrical contact are reduced.)

1. A shell-core structure MXene @ MAX composite contact reinforcing phase material is characterized by having a core-shell structure, wherein a core is a three-dimensional material MAX phase, and a shell is a two-dimensional material MXene.

2. The shell-core structure MXene @ MAX composite contact reinforcement phase material of claim 1, wherein the core MAX phase material is Ti₃SiC₂、Ti₃AlC₂、Ti₂AlC、Ti₂PbC、Ti₂SnC、Ti₂SiC、V₂AlC、Cr₂AlC、Cr₂GaC、Nb₂AlC、Ta₄AlC₃、Nb₄AlC₃、Ti₂AlN、(Ti_0.5,Nb_0.5)₂AlC、(V_0.5,Cr_0.5)₃AlC₂、(Nb_0.8,Ti_0.2)₄AlC₃In one, the shell is MXene material Ti corresponding to the MAX phase material of the inner core₃C₂、Ti₂C、V₂C、Cr₂C、Nb₂C、Ta₄C₃、Nb₄C₃、Ti₂N、(Ti_0.5,Nb_0.5)₂C、(V_0.5,Cr_0.5)₃C₂、(Nb_0.8,Ti_0.2)₄C₃。

3. The method for preparing the core-shell structure MXene @ MAX composite contact enhanced phase material as claimed in claim 1, wherein the MXene is generated in situ on the surface of the matrix MAX phase material by etching the matrix MAX phase material under an acidic condition to form the core-shell structure MXene @ MAX.

4. The method for preparing the core-shell structure MXene @ MAX composite contact reinforcing phase material according to claim 3, comprising the following steps:

s1, weighing MAX powder, adding acid liquor, placing the MAX powder into a cylindrical reaction kettle, and heating an acid liquor mixture containing MAX powder under magnetic stirring;

s2, stirring the mixture obtained in the step S1 under the condition of keeping the temperature;

s3, pouring the mixture into a centrifuge tube, and centrifuging in a centrifuge;

s4, placing the mixture after centrifugation in a freeze dryer for freeze drying.

5. The preparation method of the MXene @ MAX composite contact reinforcing phase material with the shell-core structure as claimed in claim 3 or 4, wherein the acid solution is HF acid or a mixed acid solution of HF + FLi, and the concentration of the acid solution is 20-50 wt%.

6. The preparation method of the MXene @ MAX composite contact reinforcing phase material with the shell-core structure as claimed in claim 4, wherein the MAX powder is added in an amount of 10-100 g, and the mass ratio of the acid solution to the MAX powder is (20-50): 1.

7. The method for preparing the MXene @ MAX composite contact enhanced phase material with the core-shell structure as claimed in claim 4, wherein the heating temperature of the magnetic stirrer in the step S1 is 30-70 ℃, the magnetic stirring time in the step S2 is 1-12 hours, the stirring speed is 50-250 rpm, the size of the centrifugal tube in the step S3 is 10-100 mL, the centrifugal speed is 1000-5000 rpm, the centrifugal time is 1-5 hours, and the freeze-drying time in the step S4 is 1-5 hours.

8. The Ag/MXene @ MAX composite electrical contact material is characterized in that the Ag/MXene @ MAX composite electrical contact material is prepared from the shell-core structure MXene @ MAX composite contact reinforcing phase material in the claims 1-2, wherein the mass fraction of Ag is 70-95% of the whole material, and the mass fraction of the shell-core structure MXene @ MAX composite contact reinforcing phase material is 5-30% of the whole material.

9. The method of making the Ag/MXene @ MAX composite electrical contact material of claim 8, comprising the steps of:

s1, adding Ag powder and MXene @ MAX powder into a ball mill according to the mass ratio, carrying out ball milling on the mixture by taking ethanol as a ball milling medium, and drying the ball-milled mixture in a drying box to obtain a mixture;

s2, adding the mixture obtained in the step S1 into a cold pressing die, and pressing and forming to obtain a formed biscuit;

s3, placing the biscuit in the step S2 into a sintering furnace, sintering at high temperature in a protective atmosphere, and cooling along with the furnace to obtain the Ag/MXene @ MAX composite electrical contact block material.

10. The method for preparing the Ag/MXene @ MAX composite electrical contact material as claimed in claim 9, wherein the mass ratio of the ball to the ethanol to the powder in the step S1 is (2-5): 1-3): 1, the ball milling is performed for 0.5-5 hours, and the drying is performed for 2-6 hours; in the step S2, the forming pressure is 100-800 MPa, and the pressure maintaining time is 1-10 minutes; in the step S3, the protective atmosphere is argon or nitrogen, the heating rate is 2-15 ℃/min, the sintering temperature is 600-1000 ℃, and the heat preservation time is 0.5-6 hours.

Technical Field

The invention belongs to the technical field of composite contact materials, and particularly relates to a shell-core structure MXene @ MAX composite contact reinforcing phase material and a preparation method thereof, and an Ag/MXene @ MAX composite electrical contact material prepared from the reinforcing phase material and a preparation method thereof.

Background

Low-voltage switches (contactors, circuit breakers, relays, etc.) are widely used in the fields of aerospace, rail transit, power transmission and distribution, electronics, and the like. Since the middle and later stages of the last century, the electrical contact for the low-voltage switch is mainly made of an Ag-based composite material. The universal electrical contact "Ag/CdO" occupies a large portion of the market for low voltage appliances, due to its lower resistivity and excellent resistance to arc erosion. However, with the increasingly strict global environmental protection policy (ELV Directive 2000 e.u.; WEEE Directive 2002e.u.; RoHS Directive 2003), the Cd toxicity problem will force Ag/CdO to gradually exit the electrical contact material market, and the search for alternative electrical contact materials is urgent.

Although Ag/SnO₂The electrical contact material has arc erosion resistance and fusion welding resistance which are comparable to Ag/CdO, but SnO₂The Ag-Ag alloy material has poor wettability, is easy to be deviated on the surface of an electrical contact; further, SnO₂The hardness is high, which results in poor processability of the composite electrical contact material. Ag/ZnO electrical contact materials have excellent resistance to large current impact, but ZnO also has the problems of segregation, poor processability and the like. During arc discharge, the surface C of the Ag/C electrical contact is ablated to generate CO₂CO, generating cavities, reducing fusion welding force and contact resistance; however, the extremely high material loss is the biggest drawback of the Ag/C electrical contact material. The Ag/W electrical contact has good large current ablation resistance, but an oxide layer is formed on the surface of the Ag/W electrical contact in the later working period, so that the contact resistance and the temperature rise are increased. Ag/Ni electrical contacts conduct electricity and heat well, have low and stable contact resistance, but have reduced arc erosion and fusion weld resistance above 20A.

In 2011, Barsum et al prepared a novel two-dimensional material "MXene", which is a nano-layered material similar to graphene. The special layered structure endows the novel characteristics and application potential, the MXene can be comparable to multi-layer graphene due to excellent conductivity and ductility, the chemical property of the MXene is more stable than MAX due to no A atomic layer in the MXene, in addition, the MXene has excellent friction and processing performance due to the layered structure similar to the multi-layer graphene, the conductivity of the MXene can be greatly improved by using the MXene as a reinforcing phase for a contact material, and the MXene layers are combined through molecular force, so that a good reinforcing effect on an Ag matrix cannot be achieved; in addition, the thinner MXene has a greater mass loss under arc erosion. Thus, while Ag/MXene composite electrical contact materials have good electrical conductivity, they are not the best substitute for Ag/CdO. To date, no suitable electrical contact material has been found that can serve as a complete replacement for Ag/CdO.

Disclosure of Invention

The invention aims to solve the technical problems and provides an electrical contact reinforced phase material MXene @ MAX capable of completely replacing a CdO reinforced phase, a preparation method thereof, an Ag/MXene @ MAX composite electrical contact material and a preparation method thereof.

One of the technical schemes of the invention is to provide a shell-core structure MXene @ MAX composite contact reinforcing phase material;

the second technical scheme of the invention is to provide a preparation method of the core-shell structure MXene @ MAX composite contact enhanced phase material;

the third technical scheme of the invention is to provide an Ag/MXene @ MAX composite electrical contact material;

the fourth technical scheme of the invention is to provide a preparation method of the Ag/MXene @ MAX composite electrical contact material.

One of the technical schemes of the invention is as follows: providing a shell-core structure MXene @ MAX composite contact reinforcing phase material, wherein the material has a core-shell structure, the core of the material is a three-dimensional material MAX phase, and the shell of the material is a two-dimensional material MXene;

the MXene @ MAX powder has a two-dimensional three-dimensional multi-element composite structure, the specific surface area of MXene is large, a unique interface effect is achieved, the MXene @ MAX powder is derived from a parent MAX phase, good electric conduction and heat conduction performance is achieved, the electric conduction performance is even higher than that of the parent theoretically, meanwhile, the good processing performance is given by the two-dimensional structure, and the MXene parent MAX phase has a typical three-dimensional structure, is moderate in hardness and can play a good supporting role; the MXene @ MAX composite contact reinforcing phase material which takes a three-dimensional material MAX phase as an inner core and a two-dimensional material MXene as an outer shell is compounded with an Ag matrix, so that the Ag matrix composite contact reinforcing phase material has good electric conduction, processing and arc erosion resistance, and the defects of poor Ag matrix reinforcing effect and large quality loss under arc erosion caused by the fact that the MXene is independently taken as a contact reinforcing phase material are overcome, and the defects of poor combination of the MAX independently taken as a reinforcing phase material and the Ag matrix and poor electric conduction and heat conduction are overcome.

Preferably, in the core-shell structure MXene @ MAX composite contact reinforcing phase material, the core MAX phase material is Ti₃SiC₂、Ti₃AlC₂、Ti₂AlC、Ti₂PbC、Ti₂SnC、Ti₂SiC、V₂AlC、Cr₂AlC、Cr₂GaC、Nb₂AlC、 Ta₄AlC₃、Nb₄AlC₃、Ti₂AlN、(Ti_0.5,Nb_0.5)₂AlC、(V_0.5,Cr_0.5)₃AlC₂、(Nb_0.8,Ti_0.2)₄AlC₃In one of these MAX materials, the particles are spherical particles, have high hardness (elastic modulus E: 228-414 GPa), good electrical conductivity (resistivity rho: 0.22-0.55 [ mu ] omega.m), and self-lubricating properties.

Preferably, the shell is MXene material Ti corresponding to MAX phase material of the inner core₃C₂、Ti₂C、V₂C、Cr₂C、Nb₂C、Ta₄C₃、Nb₄C₃、Ti₂N、(Ti_0.5,Nb_0.5)₂C、(V_0.5,Cr_0.5)₃C₂、(Nb_0.8,Ti_0.2)₄C₃These MXene materials are lamellar structures with a relatively low modulus of elasticity (E: -3.52 GPa) compared to MAX, but better conductivity (resistivity) compared to MAXρ:0.15～0.20μΩ·m)。

The second technical scheme of the invention is as follows: providing a preparation method of the MXene @ MAX composite contact enhanced phase material with the shell-core structure, and specifically etching the matrix MAX phase material to generate MXene in situ on the surface of the matrix MAX phase material under an acidic condition to form MXene @ MAX;

MXene is generated in situ on the surface of the matrix MAX material through chemical etching to form MXene @ MAX, the technology is simple, the cost is low, the MXene @ MAX can be formed at a low temperature, the requirement on equipment is low, the repeatability is good, the technology is simple, the cost is low, the obvious practical application value is achieved, and the MXene and the core MAX are integrated, so that the binding force is stronger and the performance is better.

Preferably, the preparation method of the core-shell structure MXene @ MAX composite contact reinforcing phase material comprises the following steps:

s1, adding MAX powder into acid liquor, placing the mixture into a cylindrical reaction kettle, and heating the acid liquor mixture containing MAX powder under magnetic stirring.

S2, stirring the mixture obtained in the step S1 under the condition of keeping the temperature;

s3, pouring the mixture into a centrifuge tube, and centrifuging in a centrifuge;

s4, placing the mixture after centrifugation into a freeze dryer for freeze drying;

preferably, in the preparation method of the MXene @ MAX composite contact reinforced phase material with the shell-core structure, the acid is HF acid or HF + FLi mixed acid solution, and the concentration is 20-50 wt%;

MAX is etched simply and quickly by using HF acid or HF + FLi mixed acid, MXene layers obtained by etching are complete and uniformly distributed, and the laminated structure cannot be etched by other acid liquor or the etching effect is not ideal.

Preferably, in the preparation method of the MXene @ MAX composite contact enhanced phase material with the shell-core structure, the adding amount of MAX powder is 10-100 g, and the mass ratio of acid liquor to MAX powder is (20-50): 1;

preferably, in the preparation method of the MXene @ MAX composite contact enhanced phase material with the shell-core structure, the heating temperature of a magnetic stirrer in the step S1 is 30-70 ℃, the magnetic stirring time in the step S2 is 1-12 hours, the stirring speed is 50-250 rpm, the size of a centrifugal tube in the step S3 is 10-100 mL, the centrifugal speed is 1000-5000 rpm, the centrifugal time is 1-5 hours, and the freeze-drying time in the step S4 is 1-5 hours;

the third technical scheme of the invention is as follows: an Ag/MXene @ MAX composite electrical contact material is prepared from the core-shell structure MXene @ MAX composite contact reinforcing phase material, wherein Ag accounts for 70-95% of the mass of the whole material, and the MXene @ MAX composite contact reinforcing phase material accounts for 5-30% of the mass of the whole material;

after MXene @ MAX is compounded with the Ag matrix, MAX plays a role in supporting a structure and enhancing an Ag base, and MXene plays a role in conducting electricity and heat, enhancing the combination with an Ag base interface, so that the density, the electric conductivity, the heat conduction and the arc erosion resistance of the Ag base electrical contact are obviously improved, and the surface temperature rise, the contact resistance and the material loss rate of the electrical contact are reduced.

The fourth technical scheme of the invention is as follows: a preparation method of an Ag/MXene @ MAX composite electrical contact material comprises the following steps:

s1, adding Ag powder and MXene @ MAX powder into a ball mill according to the mass ratio, carrying out ball milling on the mixture by taking ethanol as a ball milling medium, and drying the ball-milled mixture in a drying box to obtain a mixture;

s2, adding the mixture obtained in the step S1 into a cold pressing die for pressure forming to obtain a formed biscuit;

s3, placing the biscuit in the step S2 into a sintering furnace, carrying out high-temperature sintering in a protective atmosphere, and then cooling along with the furnace to obtain an Ag/MXene @ MAX composite electrical contact block material, wherein the block is cut, polished and welded to obtain a complete electrical contact which can be directly used as a low-voltage switch contact;

preferably, in the step S1, the ball milling media are agate balls and alcohol, the mass ratio of the balls to the ethanol to the powder is (2-5): 1-3): 1, the ball milling is carried out for 0.5-5 hours, and the drying is carried out for 2-6 hours; the molding pressure in the step S2 is 100-800 MPa, and the pressure maintaining time is 1-10 minutes; in the step S3, the protective atmosphere is argon or nitrogen, the heating rate is 2-15 ℃/min, the sintering temperature is 600-1000 ℃, and the heat preservation time is 0.5-6 hours;

the invention at least comprises the following beneficial effects:

the Ag/MXene @ MAX composite contact reinforcing phase material prepared by the method has a two-dimensional three-dimensional composite structure, excellent conductivity (the resistivity is 2.0-2.5 mu omega cm and is close to 1.6 mu omega cm of pure Ag), moderate hardness (HV 59-65), the contact assembly can be cut into various shapes, has good processability and excellent arc erosion resistance (the mass loss of the material after 6000 discharges under the national standard condition is only 110.7-124.8 mg), and the maximum content of the MXene @ MAX enhanced phase in the Ag matrix reaches 30 wt%, has obvious silver-saving effect, is suitable for large-scale production and is applied to low-voltage electrical appliances, the preparation method has the advantages of social and economic values, simple preparation process, good electric conduction, processing and arc erosion resistance, suitability for low-voltage switch equipment such as contactors, circuit breakers, relays and the like, and huge prospect in the fields of power grid distribution, new energy automobiles, aerospace and the like in the future.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a morphology diagram of a core-shell structure MXene @ MAX composite contact reinforcing phase material prepared in example 1.

Detailed Description

The present invention is described in further detail below to enable those skilled in the art to practice the invention with reference to the description.

In order to more clearly illustrate the technical solution of the present invention, the following specific examples are further illustrated.