Preparation method of silicon carbide powder

A technology of silicon carbide powder and silicon powder, which is applied in chemical instruments and methods, carbon compounds, inorganic chemistry, etc., can solve the problems of unfavorable large-scale production, high equipment investment, and a large number of workers, so as to reduce equipment and labor costs and product quality. Yield improvement, the effect of improving product yield

Active Publication Date: 2017-05-31
TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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  • Application Information

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Problems solved by technology

Compared with other methods, the combustion synthesis method has the advantages of rapidity and low energy consumption. However, since combustion synthesis requires harsh reaction conditions such as high temperature and high pressure, it is difficult to enlarge the equipment for combustion synthesis, and the volume is generally small, resulting in single-furnace synthesis. The quantity is limited, generally no more than 5kg
In order to increase production, dozens or even hundreds of devices must be used. On the one hand, this results in high investment in equipment. On the other hand, it requires a large number of workers to operate, which also increases labor costs and increases safety risks. This is very unfavorable for large-scale production

Method used

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  • Preparation method of silicon carbide powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] To prepare a silicon carbide powder, the steps are as follows:

[0043] 1) Preparation of reactants

[0044] Weigh the raw materials according to the mass ratio of silicon powder: carbon powder: nucleating agent of 69.3:29.7:1.

[0045] The purity of the silicon powder is 99.9%, the average particle size is 0.8 μm, and the silicon powder contains 10% by mass of amorphous Si;

[0046] The purity of the carbon powder is 99.5%, and the average particle size is 0.6μm;

[0047] The nucleating agent is a well-crystallized nano-SiC powder with an average grain size of 40nm.

[0048] Put the weighed raw materials into a stainless steel drum, rotate the stainless steel drum at 200 rpm for 30 minutes to fully mix the raw materials, and then pour the materials out of the stainless steel drum to obtain the reactant.

[0049] 2) Combustion synthesis

[0050] Load 110 kg of reactant into a rectangular parallelepiped graphite boat. The porosity of the blank formed by loading the reactant into the ...

Embodiment 2

[0055] To prepare a silicon carbide powder, the steps are the same as in Example 1, except that:

[0056] In step 1), weigh the raw materials according to the mass ratio of silicon powder: carbon powder: nucleating agent: catalyst of 66.5:28.5:3:2;

[0057] The silicon powder contains 50% amorphous Si by mass;

[0058] The purity of the carbon powder is 99.5%, and the average particle size is 0.5μm;

[0059] The nucleating agent is a well-crystallized nano-SiC powder with an average grain size of 20nm;

[0060] Catalyst made of SiO 2 , SiO, NH 4 F is a combination of three substances, SiO 2 : SiO: NH 4 The mass ratio of F is 30:30:40;

[0061] In step 2), the loading amount of the reactant is 100 kg, the porosity of the blank formed by loading the reactant into the graphite boat is 72%, and there are no holes larger than 200 μm in the blank, and the nitrogen pressure is 1.5 MPa.

[0062] The product yield in step 3) is 98.2%.

[0063] The obtained silicon carbide powder, XRD analysis shows...

Embodiment 3

[0065] To prepare a silicon carbide powder, the steps are the same as in Example 2, except that:

[0066] In step 1), weigh the raw materials according to the mass ratio of silicon powder: carbon powder: nucleating agent: catalyst of 67.9:29.1:2:1;

[0067] The silicon powder contains 30% by mass of amorphous Si;

[0068] The nucleating agent is a well-crystallized nano-SiC powder with an average grain size of 30nm.

[0069] In step 2), the loading amount of the reactant is 120 kg, the porosity of the blank formed by loading the reactant into the graphite boat is 70%, and the blank has no pores larger than 200 μm, and the nitrogen pressure is 1.0 MPa.

[0070] The product yield in step 3) is 98.5%.

[0071] XRD analysis of the obtained silicon carbide powder indicated that its crystal phase was beta phase silicon carbide. According to the statistics of SEM photos (measure the size of at least 200 crystal grains, and then take the average value), the average crystal grain size was 0.3 μm....

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Abstract

The invention discloses a preparation method of a silicon carbide powder. The preparation method comprises the following steps: firstly, preparing reactants: according to certain proportions, preparing silicon powder, carbon powder, a nucleating agent and a catalyst, and thoroughly mixing the raw materials, wherein the silicon powder contains 10-50% of amorphous Si by mass; then, performing combustion synthesis: putting the prepared reactants into a combustion synthesis reaction device, vacuumizing the reaction device, inflating nitrogen, igniting the reactants through heating an electrified tungsten wire, and sustainably combusting the ignited reactants till complete reaction; finally, collecting and treating a product. According to the method provided by the invention, enlargement of equipment becomes possible through creative design, and synthesis of more than 100kg of nano or sub-micron silicon carbide powder in a single furnace is achieved at a relatively low temperature and a relatively low pressure; due to the preparation method, a combustion synthesis technology of silicon carbide can be indeed popularized for large-scale industrial production, and a brand-new and low-cost production technology is provided for producing high-quality ultrafine silicon carbide powder.

Description

Technical field [0001] The invention relates to the technical field of inorganic material preparation. More specifically, it relates to a method for preparing silicon carbide powder. Background technique [0002] As an important structural ceramic material, silicon carbide ceramic has excellent characteristics such as low density, high hardness, strong wear resistance, and outstanding high temperature strength. It has been widely used in bearings, mechanical seal components, rocket nozzles, etc. As the original material for the production of silicon carbide ceramic products, the commercial demand for silicon carbide powder is also increasing year by year. In particular, high-quality sub-micron and nano-level ultra-fine silicon carbide powders have the advantages of large specific surface area and high sintering activity, making them the first choice for preparing fine-grained high-strength silicon carbide ceramics. [0003] There are many methods for preparing silicon carbide pow...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B32/984B82Y40/00
CPCB82Y40/00C01P2002/72C01P2004/03C01P2004/64
Inventor 刘光华杨增朝贺刚李江涛
Owner TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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