WO2020057094A1

WO2020057094A1 - Silicon carbide closed-cell ceramic prepared by using industrial silicon-based waste residue and preparation method therefor

Info

Publication number: WO2020057094A1
Application number: PCT/CN2019/080544
Authority: WO
Inventors: 马北越; 苏畅; 任鑫明; 于景坤
Original assignee: 东北大学
Priority date: 2018-09-20
Filing date: 2019-03-29
Publication date: 2020-03-26
Also published as: CN109133935A

Abstract

Disclosed are a silicon carbide closed-cell ceramic prepared by using an industrial silicon-based waste residue and a preparation method therefor. The silicon carbide closed-cell ceramic comprises the following components and the mass ratio thereof: an industrial silicon-based waste residue : a reducing agent : an adhesive : a sintering aid : a pore former = 100 : (30-60) : (3-5) : (5-60) : (5-60). The preparation steps include: (1) uniformly mixing materials according to the ratio of the industrial silicon-based waste residue : the reducing agent : the adhesive : the sintering aid : the pore former = 100 : (30-60) : (3-5) : (5-60) : (5-60), and ball-milling same to obtain a blended material; (2) dry-pressing and shaping, and drying the blended material; and (3) placing the dried material into a high-temperature furnace, sintering same in a reducing atmosphere and performing thermal insulation for a certain time to prepare the silicon carbide closed-cell ceramic prepared by using the industrial silicon-based waste residue. The apparent porosity of the ceramic is 30%-55%, the closed porosity of the ceramic is 12%-20%, the normal-temperature compressive strength of the ceramic is 106-140 MPa, the thermal shock resistance of the ceramic is 103-111 times, and the thermal conductivity of the ceramic is 0.40-0.69 w/( m·K).

Description

Preparation of silicon carbide closed-pore ceramics using industrial silicon-based waste slag and preparation method thereof

Technical field:

The invention belongs to the technical fields of industrial solid waste resource utilization and porous ceramic material preparation, and particularly relates to a silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste residue and a preparation method thereof.

Background technique:

With the rapid development of society, the phenomenon of resource exhaustion is common in all countries in the world. Among them, industrial waste residue has caused serious environmental and economic problems due to its large accumulation. Therefore, it is particularly important to reasonably recycle industrial waste residue and turn waste into treasure.

Closed-hole ceramics can be used as heat insulation materials in metallurgy, construction, energy and other fields due to their excellent properties such as low thermal conductivity, low density, and impermeability. Therefore, it is one of the important research directions of porous materials to produce closed-cell ceramics that are resistant to high temperature and have no hidden dangers.

SiC materials have high strength, low density, small specific gravity, excellent thermal shock resistance and oxidation resistance, etc., and are widely used in high temperature industries. Therefore, the use of industrial silicon-based waste slag as the raw material to prepare silicon carbide closed-cell ceramics can not only prepare high-temperature-resistant, safe and non-hazardous insulation materials, but also recycle industrial waste.

Summary of the invention:

The purpose of the present invention is to overcome the shortcomings of the prior art mentioned above, and provide a method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag and a method for preparing the same. The main steps of the method are as follows: first, the industrial silicon-based waste slag is pretreated To remove certain impurities, secondly, add an appropriate amount of reducing agent according to the components of the silicon-based waste residue; then, use the pre-treated silicon-based waste residue as a raw material, add a binder and a pore-forming agent, and mix the mixture; Finally, the silicon carbide closed-cell ceramics are prepared by dry pressing and sintering at high temperature under reducing conditions. .

To achieve the above objective, the present invention adopts the following technical solutions:

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag includes components and mass proportions as follows: industrial silicon-based waste slag: reducing agent: binder: sintering aid: pore former = 100: (30-60 ): (3 to 5): (5 to 60): (5 to 60).

The industrial silicon-based waste residue is one or more of coal gangue, iron ore tailings, polycrystalline silicon cutting waste, or rice hull ash, and its main component is SiO ₂ .

The reducing agent is one or more of carbon black, high-quality coal, or activated carbon.

The amount of the reducing agent should be higher than the consumption of reacting the impurities such as impurities such as silicon-based solid waste SiO ₂ , Si, and metal iron oxide with the reducing agent.

The binder is one or more of a phenol resin, water glass, aluminum dihydrogen phosphate, or polyvinyl alcohol.

The sintering aid is one or more of potassium feldspar, sodium feldspar, or anorthite.

The pore-forming agent is one or more of starch, graphite, ammonium bicarbonate or ammonium chloride.

The obtained silicon carbide closed-cell ceramic has a significant porosity of 30 to 55%, a closed porosity of 12 to 20%, a compressive strength at room temperature of 106 to 140 MPa, a thermal shock resistance of 103 to 111 times, and a thermal conductivity. The rate is 0.40 to 0.69 w / (m · K).

The thermal shock resistance of the silicon carbide closed-cell ceramics is characterized by the number of air-cooling cycles. Specific operations: After heating in a high-temperature furnace at 1000 ° C for 15 minutes, the air-cooling is performed once for 10 minutes; and then returned to the furnace and held at 1000 ° C for 15 minutes. After air-cooling for 10 minutes, the operation was repeated in this manner until the sample broke.

A method for preparing silicon carbide closed-cell ceramics by using industrial silicon-based waste slag includes the following steps:

Step 1. Mix the ingredients:

According to the ratio, industrial silicon-based waste residue: reducing agent: binder: sintering aid: pore-forming agent = 100: (30-60): (3-5) (5-60) (5-60), the materials are mixed Uniform, ball milled to obtain a homogeneous material;

Step 2. Dry pressing:

Dry mix the mixed material and dry it;

Step 3. Sintering at high temperature:

The dried material is placed in a high-temperature furnace, sintered in a reducing atmosphere, and held for a certain period of time to prepare a silicon carbide closed-cell ceramic using industrial silicon-based waste residue.

In the step 1, the industrial silicon-based waste slag is subjected to high-temperature calcination and sieving and sieving treatment before being mixed, which is used to remove impurities in the industrial silicon-based waste slag, and the silicon-based clinker is prepared and mixed according to the mixing ratio.

In the step 1, the calcining operation is performed in a calcining furnace, the calcining temperature is 900 ° C, and the calcining time is 5 hours. The calcining furnace is a box-type resistance wire furnace and silicon carbon used in an unprotected atmosphere. One of rod furnace, silicon molybdenum rod furnace and tunnel kiln.

In the step 1, the crushing and sieving process is as follows: a jaw crusher is used for crushing, and the powder is passed through a 200-mesh sieve to obtain a silicon-based clinker.

In the step 1, the silicon-based clinker and the reducing agent are ball-milled before the materials are mixed. The equipment used for the silicon-based clinker and the reducing agent ball-milling is a planetary ball mill with 200-600 r · min ^-1 The speed runs unidirectionally for 5-10 hours.

In step 1 mentioned above, the equipment used for ball milling after mixing all materials is a planetary ball mill, which runs unidirectionally at a speed of 300 r · min ^-1 for 5 hours.

In the step 2, the forming pressure is 50 to 300 MPa, and the dwell time is 3 to 5 minutes.

In the step 2, the drying temperature of the drying operation is 120 ° C., the drying time is 12-24 hours, and the drying equipment is a drying box or a tunnel drying kiln.

In step 3, the high-temperature furnace is one of a box-type resistance furnace, a tube-type resistance furnace, or a tunnel kiln that can pass through the atmosphere.

In the step 3, the sintering temperature is 1400-1600 ° C, and the sintering holding time is 2-10 hours.

In the step 3, the reducing atmosphere is a buried carbon or a CO-introduced atmosphere, wherein the conditions for the buried carbon are: dry-pressed material is placed in a graphite crucible, and the graphite crucible is placed in a large-sized corundum crucible. Put sufficient graphite powder in the corundum crucible, and cover the corundum plate with a corundum plate at the top end to isolate the graphite crucible from contact with the outside air. The CO entry conditions are: CO gas is introduced from the high temperature furnace bottom or one side of the kiln, and the gas flow rate It is 1 to 100 L / min.

The beneficial effects of the present invention:

1. The invention uses industrial silicon-based waste slag to prepare silicon carbide closed-pore ceramics and a preparation method thereof, which realizes efficient recycling and reuse of industrial silicon-based waste slag, improves its utilization rate and added value, and greatly reduces its environmental impact. Pollution has good environmental benefits.

2. A silicon carbide closed-cell ceramic prepared by using industrial silicon-based waste slag according to the present invention and a preparation method thereof. The prepared high-performance silicon carbide closed-cell ceramic has good heat preservation effect, wide source of raw materials, low price, and certain economy. benefit.

3. A silicon carbide closed-cell ceramic prepared by using industrial silicon-based waste slag according to the present invention and a preparation method thereof are simple and easy to operate and convenient for industrialized production.

Brief description of the drawings:

FIG. 1 is a process flowchart of Embodiments 1 to 6 of the present invention;

2 is an XRD pattern of a silicon carbide closed-cell ceramic prepared by using industrial silicon-based waste slag prepared in Example 2 of the present invention.

detailed description:

The present invention will be further described in detail with reference to the following embodiments.

In the following Examples 1 to 6, the thermal shock resistance of the prepared silicon carbide closed-cell ceramics is characterized by the number of air cooling cycles. The specific operation is as follows: after heating in a high-temperature furnace at 1000 ° C for 15 minutes, air cooling is performed once for 10 minutes; Put it back into the furnace and keep it at 1000 ° C for 15 minutes, and then air-cool it for 10 minutes. This operation is repeated until the sample breaks.

Example 1

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag includes components and mass proportions of: polycrystalline silicon clinker: carbon black: phenolic resin: potassium feldspar: ammonium bicarbonate = 100: 30: 5: 5: 10.

A method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag. The process flow chart is shown in Figure 1, and the following steps are performed:

Step 1: Raw material handling and weighing

(1) The polycrystalline silicon cutting waste is calcined in a box-type resistance wire furnace, after being calcined at 900 ° C for 5 hours, crushed by a jaw crusher, and sieved at 200 mesh to obtain polycrystalline silicon clinker without polyethylene glycol and water;

(2) According to the proportion, polycrystalline silicon clinker and carbon black are passed through a planetary ball mill at a speed of 200 to 600 r · min ^{-1 and} run unidirectionally for 5 to 10 hours for ball milling, then mixed with phenolic resin, potassium feldspar and ammonium bicarbonate, and Ball milling for 3h at a rate of 300r · min ^-1 to obtain a homogeneous material;

Step 2: Dry pressing

Put the mixed material in a press for dry pressing, hold it at 200 MPa for 5 minutes, and place it in a drying box at 120 ° C for 24 hours.

Step 3: High temperature sintering

The dried material was fully sintered in a box-type resistance furnace at 1500 ° C for 2 hours under the condition of buried carbon, and the high-temperature furnace was cooled to room temperature to prepare a silicon carbide closed-cell ceramic using industrial silicon-based waste residue.

After testing, the main phase of the obtained silicon carbide closed-cell ceramic is 6H-SiC, the apparent porosity is 30%, the closed porosity is 12%, the compressive strength at room temperature is 140MPa, the thermal shock resistance is 106 times, and the thermal conductivity 0.69 w / (m · K).

Example 2

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag includes components and mass ratios: polycrystalline silicon clinker: activated carbon: water glass: potassium feldspar: ammonium chloride = 100: 30: 5: 5: 20 .

Step 1: Raw material handling and weighing

(2) According to the ratio, the polycrystalline silicon clinker and activated carbon are passed through a planetary ball mill and run unidirectionally at a speed of 200-600r · min ^-1 for 5-10 hours for ball milling, then mixed with water glass, potassium feldspar and ammonium chloride, and mixed with Mill at a rate of 300r · min ^-1 for 3h to obtain a homogeneous material;

Step 2: Dry pressing

Step 3: High temperature sintering

The dried material was fully sintered in a box-type resistance furnace at 1500 ° C for 2 hours under the condition of buried carbon, and the high-temperature furnace was cooled to room temperature to prepare a silicon carbide closed-cell ceramic using industrial silicon-based waste slag. The XRD diagram is shown in Figure 2. Show.

After testing, the main phase of the obtained silicon carbide closed-cell ceramic is 6H-SiC, the apparent porosity is 40%, the closed porosity is 14%, the compressive strength at room temperature is 120MPa, the thermal shock resistance is 108 times, and the thermal conductivity It was 0.67 w / (m · K).

Example 3

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag includes components and mass ratios of: rice hull ash clinker: carbon black: phenolic resin: sodium feldspar: starch = 100: 60: 5: 5: 30.

Step 1: Raw material handling and weighing

(1) The rice husk ash is calcined in a box-type resistance wire furnace, calcined at 900 ° C for 5 hours, crushed by a jaw crusher, and sieved at 200 mesh to obtain a rice husk ash clinker with polyethylene glycol and water removed;

(2) According to the mixing ratio, the rice husk ash clinker and carbon black are subjected to ball milling through a planetary ball mill at a speed of 200 to 600 r · min-1 for one to five hours, and then mixed with phenolic resin, sodium feldspar and starch, and Ball milling for 3h at a rate of 300r · min ^-1 to obtain a homogeneous material;

Step 2: Dry pressing

Step 3: High temperature sintering

The dried material was fully sintered in a box-type resistance furnace at 1600 ° C for 2 hours under the condition of buried carbon, and the high-temperature furnace was cooled to room temperature to prepare a silicon carbide closed-cell ceramic using industrial silicon-based waste residue.

After testing, the main phase of the obtained silicon carbide closed-cell ceramic is 6H-SiC, the apparent porosity is 46%, the closed porosity is 20%, the compressive strength at room temperature is 106MPa, the thermal shock resistance is 111 times, and the thermal conductivity It was 0.46 w / (m · K).

Example 4

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag includes the following components and mass ratio: coal gangue clinker: carbon black: aluminum dihydrogen phosphate: calcium feldspar: graphite powder = 100: 40: 5: 10:30.

Step 1: Raw material handling and weighing

(1) Coal gangue is calcined in a box-type resistance wire furnace, after being calcined at 900 ° C for 5 hours, crushed by a jaw crusher, and sieved with 200 mesh to obtain coal gangue clinker with polyethylene glycol and water removed;

(2) According to the proportion, coal gangue clinker and carbon black are passed through a planetary ball mill at a speed of 200 to 600 r · min ^-1 for 5 to 10 hours in one direction, and then mixed with aluminum dihydrogen phosphate: calcium feldspar and graphite powder. And ball milling at a rate of 300 r · min ^-1 for 3 h to obtain a homogeneous material;

Step 2: Dry pressing

Step 3: High temperature sintering

After testing, the main phase of the obtained silicon carbide closed-cell ceramic is 6H-SiC, the apparent porosity is 45%, the closed porosity is 18%, the compressive strength at room temperature is 109MPa, the thermal shock resistance is 110 times, and the thermal conductivity It was 0.44 w / (m · K).

Example 5

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag includes the following components and mass ratio: coal gangue clinker: carbon black: aluminum dihydrogen phosphate: potassium feldspar: graphite powder = 100: 30: 3: 5:60.

Step 1: Raw material handling and weighing

(2) According to the mixing ratio, coal gangue clinker and carbon black are passed through a planetary ball mill at a speed of 200 to 600 r · min ^-1 for 5 to 10 hours in one direction, and then mixed with aluminum dihydrogen phosphate, potassium feldspar and graphite powder. And ball milling at a rate of 300 r · min ^-1 for 3 h to obtain a homogeneous material;

Step 2: Dry pressing

Step 3: High temperature sintering

After testing, the main phase of the obtained silicon carbide closed-cell ceramic is 6H-SiC, the apparent porosity is 55%, the closed porosity is 10%, the compressive strength at room temperature is 101MPa, the thermal shock resistance is 103 times, and the thermal conductivity It was 0.40 w / (m · K).

Example 6

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag includes the following components and mass ratio: rice hull ash clinker: carbon black: phenolic resin: sodium feldspar: starch = 100: 60: 5: 60: 30.

Step 1: Raw material handling and weighing

(2) According to the mixing ratio, the rice husk ash clinker and carbon black are subjected to ball milling through a planetary ball mill at a speed of 200 to 600 r · min ^-1 for 5 to 10 hours, and then mixed with phenolic resin, sodium feldspar and starch, and Ball milling for 3h at a rate of 300r · min ^-1 to obtain a homogeneous material;

Step 2: Dry pressing

Step 3: High temperature sintering

After testing, the main phase of the silicon carbide closed-cell ceramics obtained was 6H-SiC, the apparent porosity was 40%, the closed porosity was 16%, the compressive strength at room temperature was 119 MPa, the thermal shock resistance was 109 times, and the thermal conductivity It was 0.58 w / (m · K).

Claims

A silicon carbide closed-pore ceramic prepared by using industrial silicon-based waste slag is characterized in that it includes components and mass ratios: industrial silicon-based waste slag: reducing agent: binder: sintering aid: pore former = 100: (30 to 60): (3 to 5): (5 to 60): (5 to 60).
The method for preparing silicon carbide closed-pore ceramics using industrial silicon-based waste slag according to claim 1, wherein the industrial silicon-based waste slag is one of coal gangue, iron ore tailings, polycrystalline silicon cutting waste, or rice hull ash Or several; the reducing agent is one or more of carbon black, high-quality coal or activated carbon; the binder is one of phenolic resin, water glass, aluminum dihydrogen phosphate or polyvinyl alcohol Or more; the sintering aid is one or more of potassium feldspar, sodium feldspar or calcareous feldspar; the pore-forming agent is starch, graphite, ammonium bicarbonate or ammonium chloride One or more.
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 1, wherein the silicon carbide closed-cell ceramics exhibit a significant porosity of 30 to 55%, a closed porosity of 12 to 20%, and room temperature. The compressive strength is 106 to 140 MPa, the thermal shock resistance is 103 to 111 times, and the thermal conductivity is 0.40 to 0.69 w / (m · K).
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 3, characterized in that the thermal shock resistance of the silicon carbide closed-cell ceramics is characterized by the number of air cooling cycles, and the specific operation is at 1000 ° C. After heating in a high-temperature furnace for 15 minutes, air-cooling is performed once for 10 minutes; then put back in the furnace and kept at 1000 ° C for 15 minutes, and then air-cooled for 10 minutes. This cycle is performed until the sample is broken.
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 1, comprising the following steps:

Step 1. Mix the ingredients:

According to the ratio, industrial silicon-based waste residue: reducing agent: binder: sintering aid: pore former = 100: (30-60): (3-5) (5-60) (5-60), the materials are mixed Uniform, ball milled to obtain a homogeneous material;

Step 2. Dry pressing:

Dry mix the mixed material and dry it;

Step 3. Sintering at high temperature:

The dried material is placed in a high-temperature furnace, sintered in a reducing atmosphere, and held for a certain period of time to prepare a silicon carbide closed-cell ceramic using industrial silicon-based waste residue.
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 5, characterized in that in said step 1, the industrial silicon-based waste slag is subjected to high-temperature calcination and crushing and sieving treatment before being mixed with After removing impurities in industrial silicon-based waste slag, silicon-based clinker is prepared and mixed according to the ratio.
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 5, characterized in that in said step 1, said calcination operation is performed in a calciner, and the calcination temperature is 900 ° C, The calcining time is 5 hours. The calcining furnace is one of a box-type resistance wire furnace, a silicon carbon rod furnace, a silicon molybdenum rod furnace, and a tunnel kiln used in an unprotected atmosphere. The crushing and sieving process is as follows: : The jaw crusher is used for crushing treatment, and the powder is passed through a 200-mesh sieve to obtain a silicon-based clinker.
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 5, characterized in that, in the step 1, the silicon-based clinker and the reducing agent are subjected to ball milling before the materials are mixed. For processing, the equipment for ball milling of silicon-based clinker and reducing agent is a planetary ball mill, which runs unidirectionally at a speed of 200 ～ 600r · min -1 for 5 ～ 10h; the equipment for ball milling after all materials are mixed is a planetary ball mill with 300r · Min -1 speed running unidirectional for 5h.
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 5, characterized in that, in the step 2, the forming pressure used is 50-300 MPa, and the holding time is 3-5 minutes; The drying temperature of the drying operation is 120 ° C, the drying time is 12-24 hours, and the drying equipment is a drying box or a tunnel drying kiln.
The method for preparing silicon carbide closed-cell ceramics using industrial silicon-based waste slag according to claim 5, wherein in the step 3, the sintering temperature is 1400 to 1600 ° C, and the sintering holding time is 2 to 10h; the reducing atmosphere is buried carbon or CO-introduced, wherein: the conditions for buried carbon are: dry-pressed material is placed in a graphite crucible, the graphite crucible is placed in a large-sized corundum crucible, Fill sufficient graphite powder, cover a corundum plate on the upper end of the corundum crucible to isolate the graphite crucible from contact with the outside air; CO conditions are: CO gas is introduced from the bottom of the high temperature furnace or one side of the kiln, and the gas flow rate is 1 ～ 100L / min.