A method for preparing SiC nanorods using lignite

Abstract

A method for preparing SiC nanorods using lignite, which relates to a method for preparing SiC nanorods. The invention aims to solve the problem of how to prepare SiC nanorods using lignite. Preparation method: 1. mixing lignite and silicon source evenly, then sieving and pressing into shape; 2. carbonization reaction and sintering reaction; 3. ultrasonic treatment and grinding. The invention is used for preparing SiC nanorods using lignite.

Description

Technical Field

[0001] The invention relates to a method for preparing SiC nanorods. Background Art

[0002] Lignite, also known as wood coal, is the lowest coalification degree of mineral coal. It is a dark brown, dull and inferior coal, with a color between peat and tar coal. Silicon carbide nanorods are a new type of material with excellent mechanical, electrical and thermal properties, and are widely used in semiconductors, optoelectronic devices, energy and other fields. In industry, there are two main methods for preparing silicon carbide nanorods: chemical vapor deposition and physical vapor deposition. Silicon carbide nanorods have a wide range of applications, especially in the field of electronic devices. Due to their excellent electrical conductivity and thermal stability, they are widely used in microelectronic devices. In addition, silicon carbide nanorods can also be used in the preparation of solar cells, catalyst carriers and other fields. The existing technology mostly prepares SiC nanorods by gel injection molding, carbon thermal reduction and other methods, but the above process is complicated and costly. How to use lignite to prepare SiC nanorods is an urgent problem to be solved in the existing technology. Summary of the invention

[0003] The present invention aims to solve the problem of how to prepare SiC nanorods by using lignite, and provides a method for preparing SiC nanorods by using lignite.

[0004] A method for preparing SiC nanorods using lignite is completed by the following steps:

[0005] 1. Dry and crush the lignite, then mix the crushed lignite and silicon source by ball milling, sieve through a 120-mesh sieve, and finally press and form to obtain a block;

[0006] The mass ratio of the crushed lignite to the silicon source is (1-5):5;

[0007] 2. Under an argon atmosphere, sequentially subjecting the block to a carbonization reaction and a sintering reaction to obtain a block after the reaction;

[0008] 3. The reacted block is subjected to ultrasonic treatment and grinding in sequence to obtain SiC nanorods.

[0009] The beneficial effects of the present invention are:

[0010] 1. The present invention uses lignite as raw material, and the ash in the raw material is composed of various metal oxides and silicon dioxide. Appropriate metal particles can promote VLS reaction and are beneficial to the formation of nanorods.

[0011] 2. Lignite contains fixed carbon, organic carbon and other substances. Lignite is used as a raw material to introduce a carbon source as a reactant, and the generation of SiC is achieved by introducing a powder phase solid to interact with the carbon component in the lignite through a solid phase reaction. The reaction process is easy to control, suitable for large-scale industrial production, and reduces costs.

[0012] 3. The nanorods generated by the present invention have regular shapes and high content, which can reach 80% to 90%, and have a diameter of about 50nm and a length ranging from 100nm to several μm. They are β-SiC with a 3C phase. They are high-quality raw material powders for preparing high-performance silicon carbide ceramics and can also be used as nanomaterials, fireproof and heat-insulating materials, wave-absorbing materials, and heat storage materials.

[0013] The invention is used for a method for preparing SiC nanorods by utilizing lignite. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the XRD spectrum of the lignite described in step 1 of Example 1;

[0015] Figure 2 This is the XPS spectrum of the lignite described in step 1 of Example 1;

[0016] Figure 3 This is the XRD spectrum of the SiC nanorods prepared in Example 1;

[0017] Figure 4 This is a scanning electron microscope image of the SiC nanorods prepared in Example 1 with a scale of 200 nm;

[0018] Figure 5 This is a transmission electron microscope image of the SiC nanorods prepared in Example 1 with a scale of 500 nm. DETAILED DESCRIPTION

[0019] Specific implementation method 1: This implementation method is a method for preparing SiC nanorods using lignite, which is completed by the following steps:

[0020] 1. Dry and crush the lignite, then mix the crushed lignite and silicon source by ball milling, sieve through a 120-mesh sieve, and finally press and form to obtain a block;

[0021] The mass ratio of the crushed lignite to the silicon source is (1-5):5;

[0022] 2. Under an argon atmosphere, sequentially subjecting the block to a carbonization reaction and a sintering reaction to obtain a block after the reaction;

[0023] 3. The reacted block is subjected to ultrasonic treatment and grinding in sequence to obtain SiC nanorods.

[0024] The beneficial effects of this embodiment are:

[0025] 1. This embodiment uses lignite as raw material. The ash in the raw material is composed of various metal oxides and silicon dioxide. Appropriate metal particles can promote the VLS reaction and are beneficial to the generation of nanorods.

[0026] 2. Lignite contains fixed carbon, organic carbon and other substances. Lignite is used as a raw material to introduce a carbon source as a reactant, and the generation of SiC is achieved by introducing a powder phase solid to interact with the carbon component in the lignite through a solid phase reaction. The reaction process is easy to control, suitable for large-scale industrial production, and reduces costs.

[0027] 3. The nanorods generated in this embodiment have regular shapes and high content, which can reach 80% to 90%, and have a diameter of about 50nm and a length ranging from 100nm to several μm. They are β-SiC with a 3C phase. They are high-quality raw material powders for preparing high-performance silicon carbide ceramics and can also be used as nanomaterials, fireproof and heat-insulating materials, absorbing materials, and heat storage materials.

[0028] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the drying described in step 1 is carried out at a temperature of 60° C. to 100° C. for 1 to 2 hours. The rest is the same as specific implementation method 1.

[0029] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the silicon source described in step 1 is one or a combination of waste silicon powder, silicon dioxide, silica and organosilicon. Other aspects are the same as specific implementation method 1 or 2.

[0030] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the ball milling in step 1 is performed for 0.5 h to 6 h at a rotation speed of 150 r / min to 500 r / min and a ball-to-material ratio of (1 to 2): 1. The rest is the same as specific embodiments 1 to 3.

[0031] Specific implementation method 5: This implementation method is different from specific implementation methods 1 to 4 in that the diameter of the grinding balls used in the ball mill is 6 mm to 15 mm and the material is hard alloy. The rest is the same as specific implementation methods 1 to 4.

[0032] Specific implementation example 6: This implementation example is different from specific implementation examples 1 to 5 in that the compression molding described in step 1 is performed under a pressure of 0.1 tons to 10 tons. The rest is the same as specific implementation examples 1 to 5.

[0033] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that in step 2, argon gas is introduced at a flow rate of 20 mL / min to 100 mL / min to perform carbonization reaction and sintering reaction. The rest is the same as specific embodiments 1 to 6.

[0034] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the carbonization reaction in step 2 is carried out under an argon atmosphere at a temperature of 600° C. to 800° C. for 2 h to 6 h. The rest is the same as specific embodiments 1 to 7.

[0035] Specific embodiment 9: This embodiment is different from specific embodiments 1 to 8 in that: the sintering reaction described in step 2 is specifically carried out under an argon atmosphere, firstly heating to 50°C to 500°C at a rate of 3°C / min to 5°C / min, then heating to 700°C to 800°C at a rate of 1°C / min to 3°C / min, then heating to 900°C to 1000°C at a rate of 3°C / min to 5°C / min, and finally heating to 1400°C to 1550°C at a rate of 2°C / min to 3°C / min, and sintering for 1h to 5h at a temperature of 1400°C to 1550°C, and cooling to room temperature at a rate of 3°C / min to 5°C / min after sintering. The rest is the same as specific embodiments 1 to 8.

[0036] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that: the ultrasonic treatment described in step 3 is specifically carried out under the condition of ultrasonic power of 100W to 300W for 0.5h to 1h; the grinding described in step 3 is specifically carried out under the condition of anhydrous drying for 20min to 30min. The rest is the same as specific embodiments 1 to 9.

[0037] The following examples are used to verify the beneficial effects of the present invention:

[0038] Embodiment 1:

[0039] A method for preparing SiC nanorods using lignite is completed by the following steps:

[0040] 1. Dry and crush the lignite, then mix the crushed lignite and silicon source by ball milling, sieve through a 120-mesh sieve, and finally press and form to obtain a block;

[0041] The mass ratio of the crushed lignite to the silicon source is 1:1;

[0042] 2. Under an argon atmosphere, sequentially subjecting the block to a carbonization reaction and a sintering reaction to obtain a block after the reaction;

[0043] 3. The reacted block is subjected to ultrasonic treatment and grinding in sequence to obtain SiC nanorods.

[0044] The drying in step 1 is specifically performed at a temperature of 80° C. for 1 hour.

[0045] The silicon source described in step 1 is waste silicon powder, and the raw material comes from Inner Mongolia Haite Huacai Co., Ltd.; the lignite described in step 1 comes from lignite in Zhalainuoer, Inner Mongolia, which contains an appropriate amount of moisture (16%) and a small amount of ash (12%), and the rest are carbon and organic volatiles;

[0046] The ball milling described in step 1 is specifically carried out for 2 hours at a rotation speed of 500 r / min and a ball-to-material ratio of 1:1.

[0047] The grinding balls used in the ball mill are 10mm and 15mm in diameter with a 3:2 ratio, and are made of carbon steel balls.

[0048] The pressing and molding described in step 1 is specifically performed under a pressure of 1 ton.

[0049] In step 2, argon gas is introduced at a flow rate of 40 mL / min to carry out carbonization reaction and sintering reaction, and the purity is ≥99.99%.

[0050] The carbonization reaction in step 2 is specifically carried out under the conditions of argon atmosphere and temperature of 800° C. for 4 hours.

[0051] The sintering reaction described in step 2 is specifically carried out under an argon atmosphere, first heating to 500°C at a rate of 5°C / min, then heating to 800°C at a rate of 2.5°C / min, then heating to 1000°C at a rate of 5°C / min, and finally heating to 1500°C at a rate of 2.5°C / min. Sintering at 1500°C for 2h, and cooling to room temperature at a rate of 5°C / min after sintering.

[0052] The ultrasonic treatment described in step 3 is specifically carried out under the condition of ultrasonic power of 200W for 0.5h; the grinding described in step 3 is specifically carried out under the condition of anhydrous drying for 20min.

[0053] Figure 1 This is the XRD spectrum of the lignite described in step 1 of Example 1; it can be seen from the figure that the main component of the lignite is C.

[0054] Figure 2 This is the XPS spectrum of the lignite described in step 1 of Example 1; it can be seen from the figure that the main elements in lignite are C, O, Si and a small amount of metal peaks. Combined with XRD, it can be obtained that lignite mainly contains a large amount of C and a small amount of metal oxides and silicon dioxide.

[0055] Figure 3 This is the XRD spectrum of the SiC nanorods prepared in Example 1; as can be seen from the figure, a strong diffraction peak of SiC is produced in the final product, and it can be calculated that the SiC content can reach 88%, indicating that the method of this embodiment realizes the introduction of silicon carbide components, and it is β-SiC, and the crystal phase is 3C phase, indicating that the SiC nanorods are successfully prepared using the method in this embodiment.

[0056] Figure 4 This is a scanning electron microscope image of the SiC nanorods prepared in Example 1 with a scale of 200 nm. Figure 5 This is a transmission electron microscope image of the SiC nanorods prepared in Example 1 with a scale of 500 nm. As can be seen from the image, under Ar atmosphere, the reaction products are mostly nanorod-shaped, with a diameter of about 50 nm and a length ranging from 100 nm to several μm.

Claims

1. A method for preparing SiC nanorods using lignite, characterized in that It is done in the following steps:

1. Dry and crush the lignite, then mix the crushed lignite and silicon source by ball milling, sieve through a 120-mesh sieve, and finally press and form to obtain a block; The mass ratio of the crushed lignite to the silicon source is (1-5):5; the silicon source is waste silicon powder; the lignite is lignite from Zhalainuoer, Inner Mongolia, and the lignite is composed of 16% moisture, 12% ash, and the remainder carbon and organic volatile matter; The ball milling is specifically performed for 0.5h to 6h at a rotation speed of 150r / min to 500r / min and a ball-to-material ratio of (1 to 2):1; 2. Under an argon atmosphere, sequentially subjecting the block to a carbonization reaction and a sintering reaction to obtain a block after the reaction; Argon is introduced at a flow rate of 20 mL / min to 100 mL / min to carry out carbonization reaction and sintering reaction; The carbonization reaction is specifically carried out under the conditions of argon atmosphere and temperature of 600°C to 800°C for 2h to 6h; The sintering reaction is specifically carried out in an argon atmosphere, firstly heating to 50°C to 500°C at a rate of 3°C / min to 5°C / min, then heating to 700°C to 800°C at a rate of 1°C / min to 3°C / min, then heating to 900°C to 1000°C at a rate of 3°C / min to 5°C / min, and finally heating to 1400°C to 1550°C at a rate of 2°C / min to 3°C / min, and sintering for 1h to 5h at a temperature of 1400°C to 1550°C, and cooling to room temperature at a rate of 3°C / min to 5°C / min after sintering; 3. subjecting the reacted block to ultrasonic treatment and grinding in sequence to obtain SiC nanorods; The ultrasonic treatment is specifically carried out under the condition of ultrasonic power of 100W to 300W for 0.5h to 1h; the grinding is specifically carried out under the condition of anhydrous drying for 20min to 30min.

2. The method for preparing SiC nanorods using lignite according to claim 1, characterized in that The drying described in step 1 is specifically drying at a temperature of 60° C. to 100° C. for 1 h to 2 h.

3. The method for preparing SiC nanorods using lignite according to claim 1, characterized in that The grinding balls used in the ball mill have a diameter of 6mm to 15mm and are made of cemented carbide.

4. The method for preparing SiC nanorods using lignite according to claim 1, characterized in that The compression molding described in step 1 is specifically compression molding under a pressure of 0.1 tons to 10 tons.

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