Method for preparing spherical silica powder by high-temperature flame melting technology

Abstract

The invention discloses a method for preparing spherical silica powder by a high-temperature flame melting technology, which comprises the following steps of: (1) mixing raw materials and absolute ethyl alcohol to prepare slurry with the concentration of 30-50wt%, adding the slurry into a ball mill for ball milling until the slurry is uniformly dispersed, and sieving; the raw material is selected from one of silicon nitride, silicon metal and silicon carbide micro powder or more than two of silicon dioxide, silicon nitride, silicon metal and silicon carbide micro powder; and (2) by taking natural gas as combustible gas and oxygen as a combustion improver and carrier gas, spraying the sieved slurry into a flame region formed by combustion of the combustible gas and the oxygen under the protection of the carrier gas, and spheroidizing to prepare the spherical silica powder. The prepared silica powder is smooth in surface, good in dispersity and free of agglomeration among particles, the indexes of the spherical silica powder are equivalent to those of imported products with the same quality in the market at present, the production process is easy to control, equipment is simple, and the method has certain reference value for developing the imported replacement production process technology of the spherical silica powder with development prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic non-metallic functional materials, and particularly relates to a method for preparing spherical silicon micro-powder by high-temperature flame melting technology. BACKGROUND

[0002] The spherical silicon micro-powder is a key material in the industry of large-scale integrated circuit packaging and IC substrate, such as epoxy molding compound and liquid encapsulant for chip packaging and high-performance substrate, and has many applications in the fields of aviation, aerospace, automobile, Internet of Things and special ceramics. At present, the preparation methods of the spherical silicon micro-powder mainly include physical method and chemical method. The physical preparation method mainly includes flame balling method, high-temperature melting spraying method, plasma method and high-temperature calcination spheroidization method, etc. The chemical preparation method mainly includes gas phase method, hydrothermal synthesis method, self-propagating low-temperature combustion method, sol-gel method, precipitation method and microemulsion method, etc. The physical method for preparing the spherical silicon micro-powder requires quartz raw materials with wide sources and low cost, but has high requirements for the quality of the quartz raw materials and production equipment. The spherical quartz powder produced by the chemical method can reach or approach 100% in terms of sphericity, spheroidization rate and amorphous rate, and can also reach very low radioactive indexes, but has low bulk density and small filling amount, so that when the spherical powder is used to prepare epoxy resin plastic encapsulant, the compactness, strength and linear expansion rate of the plastic encapsulant are affected to a certain extent. Therefore, the physical method is more suitable for industrialized and large-scale production of the spherical silicon micro-powder than the chemical method. SUMMARY

[0003] The present application aims to provide a method for preparing spherical silicon micro-powder by high-temperature flame melting technology, which is easy to control and can realize large-scale industrial production of the silicon micro-powder.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a method for preparing spherical silicon micro-powder by high-temperature flame melting technology, comprising the following steps: (1) mixing raw materials and anhydrous ethanol to prepare slurry with a concentration of 30-50 wt%, ball-milling the slurry in a ball mill until it is uniformly dispersed, and sieving; the raw materials are selected from one of silicon nitride, metallic silicon and silicon carbide micro-powder, or two or more of silicon dioxide, silicon nitride, metallic silicon and silicon carbide micro-powder; (2) spraying the sieved slurry into a flame zone formed by combustion of combustible gas and oxygen under the protection of the carrier gas, spheroidizing, and obtaining spherical silicon micro-powder, wherein the combustible gas is natural gas, and the oxygen is a combustion-supporting agent and carrier gas.

[0005] Preferably, in step (1), the silicon dioxide is angular SiO2 micro-powder with an average particle size of 0.6-2.0 μm.

[0006] Preferably, in step (1), the average particle size of the silicon nitride micro-powder is 3-50 μm.

[0007] Preferably, in step (1), the average particle size of the metal silicon micro powder is 3-50 microns.

[0008] Preferably, in step (1), the raw material is composed of silicon dioxide, silicon nitride micro powder, and metal silicon micro powder in a mass ratio of 8.5:0.5:1.

[0009] Preferably, in step (1), the raw material is composed of silicon dioxide, silicon nitride micro powder, and silicon carbide micro powder in a mass ratio of 8:1:1.

[0010] Preferably, in step (1), the rotation speed of the ball mill is 200-300 r / min, and the ball milling time is 24 h.

[0011] Preferably, in step (2), the main component of natural gas is methane, and the methane is combusted with more than 99.5% pure oxygen in a ratio of 1:2-1:2.5 as the heat source for melting the powder, and the carrier gas amount is 100-150 m 3 / h, and the temperature is 2400-2600℃.

[0012] Compared with the prior art, the present application has the following beneficial effects: 1. The preparation and production process of the present application is easy to control, and the equipment is relatively simple, which has certain reference value for developing a ball-shaped silicon micro powder import substitution production process technology with development prospects.

[0013] 2. The silicon micro powder prepared by the present application has a smooth surface, good dispersibility, and no agglomeration between particles, and the index of the ball-shaped silicon micro powder is equivalent to that of the same quality product currently on the market, which is expected to realize the domestic substitution of high-end ball-shaped silicon micro powder. DETAILED DESCRIPTION

[0014] The present application provides a method for preparing ball-shaped silicon micro powder by high-temperature flame melting technology, comprising the following steps: (1) mixing raw materials and anhydrous ethanol to prepare a slurry with a concentration of 30-50 wt%, adding the slurry into a ball mill for ball milling until the slurry is uniformly dispersed, and sieving; the raw materials are selected from one of silicon nitride, metal silicon, and silicon carbide micro powder, or two or more of silicon dioxide, silicon nitride, metal silicon, and silicon carbide micro powder; (2) spraying the sieved slurry into a flame zone formed by combustion of combustible gas and oxygen under the protection of carrier gas, spheroidizing, and obtaining ball-shaped silicon micro powder.

[0015] The present application will be further described in detail below in combination with specific examples.

[0016] The raw materials used in the following examples have a purity of ≥ 99.9%, the silicon dioxide used is angular SiO2 micro powder with an average particle size of 0.6-2.0 μm; the silicon nitride micro powder used has an average particle size of 3-50 μm; the metallic silicon micro powder used has an average particle size of 3-50 μm.

[0017] Example 1 A method for preparing spherical silicon micro powder by high-temperature flame melting technology, comprising the following steps: (1) The raw materials are composed of silicon dioxide, silicon nitride micro powder and metallic silicon micro powder in a mass ratio of 8.5:0.5:1, the raw materials and anhydrous ethanol are mixed to prepare a slurry with a concentration of 30 wt%, the slurry is added into a ball mill, the rotation speed of the ball mill is 200 r / min, the ball milling time is 24 h, and the slurry is uniformly dispersed by ball milling and then sieved through a 1000-mesh sieve; (2) Natural gas is used as combustible gas, the main component of the natural gas is methane, oxygen is used as combustion-supporting agent and carrier gas, the sieved slurry is sprayed into a flame zone formed by combustion of the combustible gas and oxygen under the protection of the carrier gas, methane is combusted in a ratio of 1:2.05 with oxygen with a purity of more than 99.5% as a heat source for melting the powder, the amount of the carrier gas is 100 m 3 / h, the temperature is 2450°C, and the slurry is spheroidized to prepare spherical silicon micro powder.

[0018] Example 2 A method for preparing spherical silicon micro powder by high-temperature flame melting technology, comprising the following steps: (1) The raw materials are composed of silicon dioxide, silicon nitride micro powder and silicon carbide micro powder in a mass ratio of 8:1:1, the raw materials and anhydrous ethanol are mixed to prepare a slurry with a concentration of 40 wt%, the slurry is added into a ball mill, the rotation speed of the ball mill is 250 r / min, the ball milling time is 24 h, and the slurry is uniformly dispersed by ball milling and then sieved through a 1000-mesh sieve; (2) Natural gas is used as combustible gas, the main component of the natural gas is methane, oxygen is used as combustion-supporting agent and carrier gas, the sieved slurry is sprayed into a flame zone formed by combustion of the combustible gas and oxygen under the protection of the carrier gas, methane is combusted in a ratio of 1:2.2 with oxygen with a purity of more than 99.5% as a heat source for melting the powder, the amount of the carrier gas is 120 m 3 / h, the temperature is 2500°C, and the slurry is spheroidized to prepare spherical silicon micro powder.

[0019] Example 3 A method for preparing spherical silicon micro powder by high-temperature flame melting technology, comprising the following steps: (1) The raw materials are composed of silicon dioxide, silicon nitride micro powder and metallic silicon micro powder in a mass ratio of 8.5:0.5:1, the raw materials and anhydrous ethanol are mixed to prepare a slurry with a concentration of 50 wt%, the slurry is added into a ball mill, the rotation speed of the ball mill is 300 r / min, the ball milling time is 24 h, and the slurry is uniformly dispersed by ball milling and then sieved through a 1000-mesh sieve; (2) natural gas as the combustible gas, the main component of natural gas is methane, oxygen as the combustion-supporting agent and carrier gas, the sieved slurry is sprayed into the flame zone formed by the combustion of combustible gas and oxygen under the protection of carrier gas, methane is combusted with more than 99.5% pure oxygen in a ratio of 1:2.5, as the heat source of the molten powder, the carrier gas amount is 150 m 3 / h, the temperature is 2600℃, spheroidization, spherical silicon micro powder is prepared.

[0020] The physical properties of the spherical silicon micro powder sample prepared by the high-temperature flame melting method, such as average particle size (D50), spheroidization rate, specific surface area, specific gravity, whiteness, conductivity, pH value, etc. are analyzed, and the test methods are as follows: Determination of average particle size D50: JI-1155 laser particle size analyzer; Determination of spheroidization rate: SU8010 field emission scanning electron microscope; Determination of specific surface area: BSD-PM1 specific surface analyzer; Determination of specific gravity: BSD-TD full-automatic true density analyzer; Determination of whiteness: TC-BDY48 whiteness meter; Determination of conductivity: DDS-801A conductivity meter.

[0021] The test results are shown in Table 1.

[0022] Table 1 Test results of physical property analysis of spherical silicon micro powder sample The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement made by those skilled in the art within the technical range disclosed by the present application, within the spirit and principles of the present application, should be covered within the protection scope of the present application.

Claims

1. A method for preparing spherical silica micropowder using high-temperature flame melting technology, characterized in that, Includes the following steps: (1) The raw materials and anhydrous ethanol are mixed to prepare a slurry with a concentration of 30-50 wt%, which is then added to a ball mill and ball-milled until evenly dispersed, and then sieved; the raw materials are selected from one of silicon nitride, metallic silicon and silicon carbide micro powder or two or more of silicon dioxide, silicon nitride, metallic silicon and silicon carbide micro powder. (2) Using natural gas as the combustible gas and oxygen as the combustion aid and carrier gas, the slurry after sieving is sprayed into the flame zone formed by the combustion of combustible gas and oxygen under the protection of the carrier gas, and spherical silicon micro powder is obtained.

2. The method for preparing spherical silicon micropowder using high-temperature flame melting technology according to claim 1, characterized in that, In step (1), the silicon dioxide is angular SiO2 micro powder with an average particle size of 0.6 to 2.0 μm; the silicon nitride micro powder has an average particle size of 3 to 50 μm; and the metallic silicon micro powder has an average particle size of 3 to 50 μm.

3. The method for preparing spherical silica powder using high-temperature flame melting technology according to claim 1, characterized in that, In step (1), the raw materials are composed of silicon dioxide, silicon nitride micro powder and metallic silicon micro powder in a mass ratio of 8.5:0.5:

1.

4. The method for preparing spherical silicon micropowder using high-temperature flame melting technology according to claim 1, characterized in that, In step (1), the raw materials are composed of silicon dioxide, silicon nitride micro powder and silicon carbide micro powder in a mass ratio of 8:1:

1.

5. The method for preparing spherical silicon micropowder using high-temperature flame melting technology according to claim 1, characterized in that, In step (1), the ball milling speed is 200-300 r / min and the ball milling time is 24 h.

6. The method for preparing spherical silica powder using high-temperature flame melting technology according to claim 1, characterized in that, In step (2), the main component of natural gas is methane. Methane is mixed with pure oxygen (99.5% or higher) at a ratio of 1:2 to 1:2.5 and burned as a heat source for the molten powder. The carrying capacity of the gas is 100 to 150 m³. 3 / h, temperature is 2400~2600℃.

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