CN112079640A

CN112079640A - MoSi2@ZrO2Preparation method of core-shell structure

Info

Publication number: CN112079640A
Application number: CN202010702108.0A
Authority: CN
Inventors: 张建军; 刘靠斌; 韦学龙; 梁炳亮; 陈卫华; 何文; 欧阳晟; 艾云龙
Original assignee: Nanchang Hangkong University
Current assignee: Nanchang Hangkong University
Priority date: 2020-07-21
Filing date: 2020-07-21
Publication date: 2020-12-15
Anticipated expiration: 2040-07-21
Also published as: CN112079640B

Abstract

The invention discloses MoSi₂@ZrO₂The preparation method of the core-shell structure comprises the following steps of (1) MoSi₂Adding the powder and SDS into a beaker, mechanically and ultrasonically stirring, and using water or alcohol as a dispersion medium; (2) dispersing for a certain time, adding a zirconium source into the suspension, and dropwise adding an alkaline solution NH₃·H₂O or NaOH until the PH value is between 7 and 14; continuously stirring for a certain time until the mixture is uniformly mixed; (3) placing the prepared suspension in a reaction kettle, and curing for 12-48 h at 160-220 ℃; heating by using an oven, and keeping the temperature of the suspension after the suspension reaches a certain temperature through a certain heating rate; (4) after hydrothermal reaction synthesis, filtering, washing, drying and sieving to obtain powder; (5) calcining the prepared powder in calcining equipment for 1-6 hours at the heat preservation temperature of 300-400 ℃; (6) obtaining MoSi through the steps₂@ZrO₂Core-shell structure of synthetic ZrO₂The volume fraction of the powder is 10-30 vol%. The invention adopts a hydrothermal method, has no pollution, reduces the requirement of equipment and is environment-friendly.

Description

MoSi2@ZrO2Preparation method of core-shell structure

Technical Field

The invention relates to the technical field of preparation of high-performance ceramic matrix composite powder, in particular to MoSi₂@ZrO₂A preparation method of a core-shell structure.

Background

MoSi₂Has the advantages of higher melting point (2303K), high strength, good thermal conductivity and the like, and is a candidate material of the next generation high-temperature material. In particular, it is considered to be a promising high temperature coating for aerospace, nuclear industry, metallurgy and electronics. MoSi₂The low-temperature brittleness (BDTT is 900-1000 ℃), the high-temperature strength above 1300 ℃ is insufficient, and especially the creep resistance is low. And about 400-600 ℃ MoSi₂Accelerated oxidation occurs and eventually changes from a dense body to a powder, a phenomenon known as Pest. These disadvantages limit MoSi₂As an application for high temperature structures. Thus, room temperature toughening and high temperature reinforcement, and suppression of low temperature Pest to MoSi₂There is a need for a key problem to be solved.

The hydrothermal method is to prepare ZrO₂An important method for preparing powder features that the preparing process is completed at high temp. and pressure in one step without need of later crystallizing treatment, and the obtained powder has narrow granularity distribution and pure components.

The core-shell type nano-particle is a composite multi-item structure formed by taking a particle with the size ranging from a micron to a nano film as a core and coating a plurality of layers of uniform nano films on the surface of the particle, and the core and the shell are mutually connected through physical or chemical action. The chemical inertness of the cladding layer in the core-shell composite material can improve the stability of the nano particles, so that the core-shell structure material has more excellent physical and chemical properties than the single-center particle, and has wide application prospect.

The MoSi is obtained by adopting mechanical stirring dispersion and hydrothermal synthesis₂@ZrO₂A core-shell structure. Coated with several layers of ZrO₂With the object of preventing MoSi₂And the alloy is oxidized at low temperature (400-600 ℃) to enhance the room temperature strength and the fracture toughness. Is MoSi₂The wide application of the base composite material lays a foundation.

Disclosure of Invention

The invention aims to solve the problems that: provides a MoSi₂@ZrO₂Method for preparing core-shell structure from MoSi₂As a matrix, by adding ZrOCl₂·8H₂O in the hydrothermal synthesis process, ZrO is synthesized₂Further coating with MoSi₂. Elimination of MoSi during sintering₂ZrO produced by hydrothermal reaction under the harm of low-temperature oxidation₂Thereby obtaining MoSi₂@ZrO₂A core-shell structure. This provides for further improvement of the mechanical properties of the composite material in the future.

The technical scheme provided by the invention for solving the problems is as follows: MoSi₂@ZrO₂A method for preparing a core-shell structure, the method comprising the steps of,

(1) certain proportion of MoSi₂Adding the powder and SDS into a beaker, mechanically and ultrasonically stirring, and using water or alcohol as a dispersion medium;

(2) after dispersing for a certain time, adding a certain amount of zirconium source into the suspension, and dropwise adding an alkaline solution NH₃·H₂O or NaOH until the PH value is between 7 and 14; continuously stirring for a certain time until the mixture is uniformly mixed;

(3) placing the prepared suspension in a reaction kettle, and curing for 12-48 h at 160-220 ℃; heating by using an oven, and keeping the temperature of the suspension after the suspension reaches a certain temperature through a certain heating rate;

(4) after hydrothermal reaction synthesis, filtering, washing, drying and sieving to obtain powder;

(5) calcining the prepared powder in calcining equipment for 1-6 hours at the heat preservation temperature of 300-400 ℃;

(6) mo is obtained through the stepsSi₂@ZrO₂Core-shell structure of synthetic ZrO₂The volume fraction of the powder is 10-30 vol%.

Preferably, the dispersion time in the step (2) is 1-6 h.

Preferably, the calcining equipment in the step (5) is an atmosphere tube furnace, a high-temperature vacuum furnace or a microwave sintering furnace.

Preferably, the heating rate of the calcination in the step (5) is 5-20 ℃/min, the heat preservation time is 30-180 min, and the calcination atmosphere is vacuum, argon atmosphere or nitrogen atmosphere.

Compared with the prior art, the invention has the advantages that:

(1) dispersing MoSi by adopting a mechanical stirring method₂Powder, avoiding powder agglomeration and obtaining uniform suspension.

(2) And a hydrothermal method is adopted, so that the method is pollution-free, reduces the requirements of equipment and is environment-friendly.

(3) The preparation process is completed at one time under high temperature and high pressure, the later crystallization treatment is not needed, and the obtained powder has narrow particle size distribution and pure components.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 shows MoSi₂@ZrO₂XRD pattern of core-shell structure.

FIG. 2 shows the preparation of MoSi in example 1₂@ZrO₂TEM image of core-shell structure.

Detailed Description

The embodiments of the present invention will be described in detail with reference to the accompanying drawings and examples, so that how to implement the technical means for solving the technical problems and achieving the technical effects of the present invention can be fully understood and implemented.

Example 1

2.5g of MoSi after ball milling₂The powder and the dispersing agent 1.6g/L SDS were added to a beaker containing 200ml of distilled water and mechanically agitated ultrasonically, using water as the dispersing agentA medium; after 6h of dispersion, 1.5338g of ZrOCl as a zirconium source were added to the suspension₂·8H₂O, calculated as 20% vol ZrO₂. Alkaline solution NH is dripped₃·H₂O to PH 9 or so. Stirring for 3h until uniform. And (3) placing the prepared suspension into a reaction kettle, heating to 200 ℃ by using an oven, and curing for 24 hours at the temperature of 200 ℃. After the hydrothermal reaction synthesis, the composite powder is obtained by filtering with distilled water and alcohol, washing for three times respectively, drying, and sieving with a 200-mesh sieve. Calcining the prepared powder in an atmosphere tube furnace for 3 hours at the temperature of 380 ℃. Through the steps, MoSi is obtained₂@ZrO₂A core-shell structure.

The foregoing is merely illustrative of the preferred embodiments of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiments, and the specific structure thereof is allowed to vary. All changes which come within the scope of the invention as defined by the independent claims are intended to be embraced therein.

Claims

1. MoSi₂@ZrO₂The preparation method of the core-shell structure is characterized by comprising the following steps: the method comprises the following steps of,

(6) obtaining MoSi through the steps₂@ZrO₂Core-shell structure of synthetic ZrO₂The volume fraction of the powder is 10-30 vol%.

2. MoSi according to claim 1₂@ZrO₂The preparation method of the core-shell structure is characterized by comprising the following steps: and (3) the dispersion time in the step (2) is 1-6 h.

3. MoSi according to claim 1₂@ZrO₂The preparation method of the core-shell structure is characterized by comprising the following steps: and (5) calcining equipment is an atmosphere tube furnace, a high-temperature vacuum furnace and a microwave sintering furnace.

4. MoSi according to claim 1₂@ZrO₂The preparation method of the core-shell structure is characterized by comprising the following steps: the temperature rise rate of the calcination in the step (5) is 5-20 ℃/min, the heat preservation time is 30-180 min, and the calcination atmosphere is vacuum, argon atmosphere or nitrogen atmosphere.