阅读说明：本技术 一种铬催化的碳化硅晶须及其制备方法 (Chromium-catalyzed silicon carbide whisker and preparation method thereof ) 是由 邓先功 郝晶淼 季鹏 邓海亮 丁祥 冉松林 张毅 樊传刚 于 2021-08-24 设计创作，主要内容包括：本发明属于碳化硅晶须技术领域,具体涉及一种铬催化的碳化硅晶须及其制备方法,制备方法包括如下步骤：1)按配比称取铬源、硅粉、碳源,将铬源、硅粉与碳源混合均匀,制得混合粉体；2)按配比称取粘结剂,将粘结剂加入到混合粉体中,混合均匀,困料,压制成型,制得坯体；3)将坯体在80-180℃下干燥6-48h,然后在埋碳条件下,经1100-1500℃热处理l-10h,即制得铬催化的碳化硅晶须。本发明对设备要求低,具有制备工艺简单、易于操控、成本相对较低的特点；用该方法制备的碳化晶须具有数量多、长径比大、纯度高和应用前景大的优点。(The invention belongs to the technical field of silicon carbide whiskers, and particularly relates to a chromium-catalyzed silicon carbide whisker and a preparation method thereof, wherein the preparation method comprises the following steps: 1) weighing a chromium source, silicon powder and a carbon source according to the proportion, and uniformly mixing the chromium source, the silicon powder and the carbon source to prepare mixed powder; 2) weighing the binder according to the proportion, adding the binder into the mixed powder, uniformly mixing, ageing, and performing compression molding to obtain a blank; 3) drying the blank at 80-180 ℃ for 6-48h, and then carrying out heat treatment at 1100-1500 ℃ for l-10h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker. The invention has low requirement on equipment, and has the characteristics of simple preparation process, easy operation and control and relatively low cost; the carbonization crystal whisker prepared by the method has the advantages of large quantity, large length-diameter ratio, high purity and wide application prospect.)

1. A preparation method of chromium-catalyzed silicon carbide whiskers is characterized by comprising the following steps:

1) weighing a chromium source, silicon powder and a carbon source according to the proportion, and uniformly mixing the chromium source, the silicon powder and the carbon source to prepare mixed powder;

2) weighing the binder according to the proportion, adding the binder into the mixed powder, uniformly mixing, ageing, and performing compression molding to obtain a blank;

3) drying the blank at 80-180 ℃ for 6-48h, and then carrying out heat treatment at 1100-1500 ℃ for l-10h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

2. The method of claim 1, wherein the method comprises: in the step 1), the mass ratio of the chromium source to the silicon powder to the carbon source is 0.025-0.15:1.5-3.5: 1.

3. The method of claim 1, wherein the method comprises: in the step 1), the chromium source is one of chromium chloride, chromium sesquioxide, chromium sulfate and chromium nitrate, and the chromium chloride, the chromium sesquioxide, the chromium sulfate and the chromium nitrate are industrially pure or analytically pure.

4. The method of claim 1, wherein the method comprises: in the step 1), the content of Si in the silicon powder is more than or equal to 90 percent, and the particle size is less than or equal to 100 mu m.

5. The method of claim 1, wherein the method comprises: in the step 1), the carbon source is one of microcrystalline graphite, crystalline flake graphite, expanded graphite and nano carbon black, and the microcrystalline graphite, the crystalline flake graphite, the expanded graphite and the nano carbon black are industrially pure or analytically pure.

6. The method of claim 1, wherein the method comprises: in the step 2), the mass ratio of the binder to the mixed powder is 0.01-0.1: 1.

7. The method of claim 1, wherein the method comprises: in the step 2), the binder is one of PVA solution, dextrin solution, phenolic resin and asphalt, and the PVA, the phenolic resin, the asphalt and the dextrin are of industrial purity or analytical purity.

8. A chromium-catalyzed silicon carbide whisker, characterized in that it is produced by the production method according to any one of claims 1 to 7.

Technical Field

The invention belongs to the technical field of silicon carbide crystal whiskers, and particularly relates to a chromium-catalyzed silicon carbide crystal whisker and a preparation method thereof.

Background

The silicon carbide whisker has the advantages of high melting point, excellent mechanical property, small thermal expansion coefficient, corrosion resistance and the like, is an excellent toughening reinforcement of the ceramic matrix composite, can greatly improve the comprehensive performance of the composite, and is widely used in the fields of aerospace, high-temperature kilns, machinery, chemical industry and the like. The preparation method of the silicon carbide whisker mainly comprises a carbothermic method, a microwave heating method, a vapor deposition method, a direct reaction method and the like. The carbothermic method for preparing the silicon carbide crystal whisker has high reaction temperature and large energy consumption, and SiO in the product₂Impurities are difficult to separate. Although the microwave heating method has the advantages of high heating rate, low reaction temperature, cleanness and environmental protection, the equipment used by the method has high price and is difficult to produce on a large scale. The vapor deposition method can synthesize the silicon carbide crystal whisker with high purity, but the yield is extremely limited, and the industrial application is difficult.

The direct reaction method is one of the most common methods for preparing the silicon carbide crystal whisker, and has the advantages of simple process, easy large-scale production, low cost and the like. However, it has the disadvantages of high heat treatment temperature, long reaction time, few silicon carbide whiskers, small aspect ratio and the like. In recent years, in order to prepare silicon carbide whiskers with high cost performance, researchers add catalysts such as iron, cobalt and nickel in the preparation process to catalyze and prepare the silicon carbide whiskers.

In a word, the existing silicon carbide whisker preparation method has the defects of high reaction temperature, high energy consumption, slow reaction rate, incomplete reaction, expensive equipment and the like, and greatly limits the application and large-scale production of the silicon carbide whisker.

Disclosure of Invention

The invention aims to overcome at least one of the problems in the prior art and provide a preparation method of the silicon carbide whisker, which has the advantages of simple process, easy control and low cost, and the silicon carbide whisker prepared by the method has the advantages of large quantity, large length-diameter ratio, high purity and wide industrial application prospect.

In order to achieve the technical purpose and achieve the technical effect, the invention is realized by the following technical scheme:

a preparation method of chromium-catalyzed silicon carbide whiskers comprises the following steps:

1) weighing a chromium source, silicon powder and a carbon source according to the proportion, and uniformly mixing the chromium source, the silicon powder and the carbon source to prepare mixed powder;

2) weighing the binder according to the proportion, adding the binder into the mixed powder, uniformly mixing, ageing, and performing compression molding to obtain a blank;

3) drying the blank at 80-180 ℃ for 6-48h, and then carrying out heat treatment at 1100-1500 ℃ for l-10h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

Further, in the preparation method of the chromium-catalyzed silicon carbide whisker, in the step 1), the mass ratio of the chromium source to the silicon powder to the carbon source is 0.025-0.15:1.5-3.5: 1.

Further, in the preparation method of the chromium-catalyzed silicon carbide whisker, in step 1), the chromium source is one of chromium chloride, chromium sesquioxide, chromium sulfate and chromium nitrate, and the chromium chloride, the chromium sesquioxide, the chromium sulfate and the chromium nitrate are industrially pure or analytically pure.

Further, in the preparation method of the chromium-catalyzed silicon carbide whisker, in the step 1), the content of Si in the silicon powder is more than or equal to 90%, and the particle size is less than or equal to 100 μm.

Further, in the preparation method of the chromium-catalyzed silicon carbide whisker, in step 1), the carbon source is one of microcrystalline graphite, crystalline flake graphite, expanded graphite and nano carbon black, and the microcrystalline graphite, the crystalline flake graphite, the expanded graphite and the nano carbon black are industrially pure or analytically pure.

Further, in the preparation method of the chromium-catalyzed silicon carbide whisker, in the step 2), the mass ratio of the binder to the mixed powder is 0.01-0.1: 1.

Further, in the preparation method of the chromium-catalyzed silicon carbide whisker, step 2), the binder is one of PVA solution, dextrin solution, phenolic resin and asphalt, and the PVA, the phenolic resin, the asphalt and the dextrin are industrial pure or analytical pure.

The chromium-catalyzed silicon carbide whisker is prepared by the preparation method.

The invention has the beneficial effects that:

1. the invention has low requirement on equipment, and has the characteristics of simple preparation process, easy operation and control and relatively low cost; the carbonization crystal whisker prepared by the method has the advantages of large quantity, large length-diameter ratio, high purity and wide application prospect.

2. The preparation process of the silicon carbide whisker can be directly used for preparing a reinforcement body of the whisker reinforced carbon-containing refractory material by in-situ catalysis, and the improvement of the mechanical property of the refractory material is realized.

Of course, it is not necessary for any one product that embodies the invention to achieve all of the above advantages simultaneously.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an SEM image of silicon carbide whiskers prepared in example 3 of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A preparation method of chromium-catalyzed silicon carbide whiskers comprises the following steps:

1) weighing a chromium source, silicon powder and a carbon source according to the proportion, and uniformly mixing the chromium source, the silicon powder and the carbon source to prepare mixed powder; the mass ratio of the chromium source to the silicon powder to the carbon source is 0.025-0.15:1.5-3.5: 1. The chromium source is one of chromium chloride, chromium sesquioxide, chromium sulfate and chromium nitrate, and the chromium chloride, chromium sesquioxide, chromium sulfate and chromium nitrate are industrially pure or analytically pure. The Si content in the silicon powder is more than or equal to 90 percent, and the grain diameter is less than or equal to 100 mu m. The carbon source is one of microcrystalline graphite, crystalline flake graphite, expanded graphite and nano carbon black, and the microcrystalline graphite, the crystalline flake graphite, the expanded graphite and the nano carbon black are industrially pure or analytically pure.

2) Weighing the binder according to the proportion, adding the binder into the mixed powder, uniformly mixing, ageing, and performing compression molding to obtain a blank. The mass ratio of the adhesive to the mixed powder is 0.01-0.1: 1. The binder is one of PVA solution, dextrin solution, phenolic resin and asphalt, and the PVA, the phenolic resin, the asphalt and the dextrin are of industrial purity or analytical purity.

3) Drying the blank at 80-180 ℃ for 6-48h, and then carrying out heat treatment at 1100-1500 ℃ for l-10h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

The specific embodiment of the invention is as follows:

example 1

A preparation method of chromium-catalyzed silicon carbide whiskers comprises the following steps:

1) uniformly mixing chromium chloride, silicon powder and microcrystalline graphite according to the mass ratio of 0.025:1.5:1 to prepare mixed powder;

2) adding a PVA solution into the mixed powder according to the mass ratio of the binder to the mixed powder of 0.01:1, uniformly mixing, ageing, and performing compression molding to obtain a blank;

3) and drying the blank at 80 ℃ for 48h, and then carrying out heat treatment at 1100 ℃ for 6h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

Example 2

A preparation method of chromium-catalyzed silicon carbide whiskers comprises the following steps:

1) uniformly mixing chromium sulfate, silicon powder and expanded graphite according to the mass ratio of 0.05:1.9:1 of chromium sulfate to silicon powder to expanded graphite to prepare mixed powder;

2) adding asphalt into the mixed powder according to the mass ratio of the binder to the mixed powder of 0.03:1, uniformly mixing, ageing, and performing compression molding to obtain a blank;

3) and drying the blank at 100 ℃ for 36h, and then carrying out heat treatment at 1200 ℃ for 4h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

Example 3

A preparation method of chromium-catalyzed silicon carbide whiskers comprises the following steps:

1) uniformly mixing chromium sesquioxide, silicon powder and nano carbon black according to the mass ratio of the chromium sesquioxide to the silicon powder to the nano carbon black of 0.10:2.3:1 to prepare mixed powder;

2) adding phenolic resin into the mixed powder according to the mass ratio of the binder to the mixed powder of 0.05:1, uniformly mixing, ageing, and performing compression molding to obtain a blank;

3) and drying the blank at 120 ℃ for 24h, and then carrying out heat treatment at 1400 ℃ for 2h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

The SEM image of the silicon carbide whisker prepared in the example is shown in FIG. 1.

Example 4

A preparation method of chromium-catalyzed silicon carbide whiskers comprises the following steps:

1) uniformly mixing chromium nitrate, silicon powder and crystalline flake graphite according to the mass ratio of 0.15:2.7:1 to prepare mixed powder;

2) adding asphalt into the mixed powder according to the mass ratio of the binder to the mixed powder of 0.07:1, uniformly mixing, ageing, and performing compression molding to obtain a blank;

3) and drying the blank at 140 ℃ for 12h, and then carrying out heat treatment at 1300 ℃ for 3h under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

Example 5

A preparation method of chromium-catalyzed silicon carbide whiskers comprises the following steps:

1) uniformly mixing chromium chloride, silicon powder and microcrystalline graphite according to the mass ratio of 0.08:3.1:1 to prepare mixed powder;

2) adding phenolic resin into the mixed powder according to the mass ratio of the binder to the mixed powder of 0.03:1, uniformly mixing, ageing, and performing compression molding to obtain a blank;

3) and drying the blank at 140 ℃ for 10h, and then carrying out thermal treatment l h at 1500 ℃ under the condition of carbon embedding to obtain the chromium-catalyzed silicon carbide whisker.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.