A method for preparing silicon oxide evaporation material

Abstract

The present invention provides a method for preparing silicon oxide evaporation material, the preparation method comprising the following steps: mixing silicon oxide powder with a binder and then ball milling to obtain a mixed powder; cold isostatic pressing the obtained mixed powder to obtain a blank; crushing the obtained blank and then sintering to obtain a sintered material; grading and sieving the obtained sintered material to obtain a silicon oxide evaporation material. The silicon oxide evaporation material prepared by the preparation method provided by the present invention has high purity and high density, especially can reach more than 99.0%, uniform particle size, no residue on the surface, stable performance when used for evaporation, and good evaporation effect.

Description

Technical Field

[0001] The invention belongs to the technical field of evaporation coating, relates to an evaporation material, and specifically relates to a method for preparing a silicon oxide evaporation material. Background Art

[0002] Vacuum evaporation coating refers to a technology that obtains a thin film by heating and evaporating a certain substance under vacuum conditions so that it is deposited on the surface of the substrate material. The evaporated substance is called the evaporation material. Vacuum evaporation coating technology has the characteristics of simplicity, convenience, and fast film formation. It is mainly used for coating of optical components, LEDs, flat panel displays, and semiconductor discretes. With the rapid development of the optical industry, high-end industries have higher and higher performance requirements for evaporation materials, and the quality of evaporation materials directly affects the quality of coating.

[0003] CN104557039A discloses a medium-refractive-index evaporation coating material, a preparation process and an application thereof. The evaporation coating material comprises lanthanum oxide, aluminum oxide and silicon dioxide, and is prepared by sequentially performing a mixing reaction, pressing and high-temperature sintering process. A single-layer film with a refractive index of 1.75 can be obtained by evaporation, and the stability is good.

[0004] CN107285753A discloses a method for preparing a low-refractive index evaporation material, which comprises: mixing SiO2 and Al2O3, and then sequentially performing ball milling, slurry drying, tableting, sintering and cleaning. The obtained evaporation material has the advantages of no splashing, high density and stable evaporation rate when used for film coating.

[0005] CN115893992A discloses a method for preparing a silicon aluminum oxide ceramic evaporation material. The evaporation material is prepared by first preparing a silicon source precursor solution, then mixing it with SiO2 and Al2O3 for ball milling, and then sequentially performing microwave heat treatment, microwave sintering, pressing and molding, high-temperature sintering and cooling processes. The obtained material is not prone to splashing during evaporation.

[0006] In the prior art, the prepared evaporation materials often have uneven particle sizes, low purity and density, and are difficult to meet the requirements of the high-end optical coating industry.

[0007] Therefore, in view of the shortcomings of the prior art, a method for preparing a silicon oxide evaporation material is needed. Summary of the invention

[0008] The object of the present invention is to provide a method for preparing a silicon oxide evaporation material, which can obtain a silicon oxide evaporation material with high purity, high density, uniform particle size and high yield.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] The present invention provides a method for preparing a silicon oxide evaporation material, the preparation method comprising the following steps:

[0011] (1) mixing silicon oxide powder and a binder and then ball milling to obtain a mixed powder;

[0012] (2) cold isostatically pressing the mixed powder obtained in step (1) to obtain a blank;

[0013] (3) crushing the blank obtained in step (2) and then sintering it to obtain a sintered material;

[0014] (4) The sintered material obtained in step (3) is graded and sieved to obtain silicon oxide evaporation material.

[0015] The preparation method of the silicon oxide evaporation material provided by the present invention adopts a powder metallurgy method. By molding and sintering silicon oxide powder, a silicon oxide evaporation material with high purity, high density, uniform particle size and no slag on the surface can be prepared, and the evaporation performance is excellent.

[0016] Preferably, the purity of the silicon oxide powder in step (1) is ≥99.99%, for example, it can be 99.99%, 99.992%, 99.994%, 99.995%, 99.996%, 99.998% or 99.999%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the D50 particle size of the silicon oxide powder in step (1) is 1-10 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the binder in step (1) comprises sodium silicate and / or polyvinyl alcohol.

[0019] Preferably, the amount of the binder in step (1) is 0.5-6wt% of the silicon oxide powder, for example, it can be 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt% or 6wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the ball-to-material mass ratio of the ball milling in step (1) is 1:(3-6), for example, it can be 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5 or 1:6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the rotation speed of the ball mill in step (1) is 30-80 r / min, for example, it can be 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min or 80 r / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the ball milling time in step (1) is ≥12 h, for example, it can be 12 h, 15 h, 18 h, 20 h, 25 h, 30 h, 40 h or 50 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the pressure of the cold isostatic pressing in step (2) is 180-280 MPa, for example, 180 MPa, 200 MPa, 220 MPa, 240 MPa, 260 MPa or 280 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, the cold isostatic pressing time in step (2) is 2-8 min, for example, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min or 8 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the end point of the pulverization in step (3) is that the particle size range is 6-10 mm, for example, it can be 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0026] Preferably, the thickness of the sintered charge in step (3) is less than 15 mm, for example, it can be 2 mm, 5 mm, 8 mm, 10 mm, 12 mm or 14 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the sintering in step (3) is carried out in an oxygen atmosphere.

[0028] Preferably, the heating rate of the sintering in step (3) is 1-8°C / min, for example, it can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min or 8°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the sintering in step (3) includes a first sintering, a second sintering and a third sintering performed sequentially.

[0030] Preferably, the first sintering temperature is 200-400°C, for example, 200°C, 250°C, 300°C, 350°C or 400°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the first sintering time is 0.5-2 h, for example, 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h or 2 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the second sintering temperature is 1000-1300°C, for example, it can be 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C or 1300°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, the second sintering time is 0.5-2 h, for example, 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h or 2 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the temperature of the third sintering is 1400-1650°C, for example, it can be 1400°C, 1450°C, 1500°C, 1550°C, 1600°C or 1650°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the third sintering time is 10-14 h, for example, 10 h, 11 h, 12 h, 13 h or 14 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] During the sintering process, the silicon oxide blank is further densified by bonding between the powder particles and reducing the surface free energy of the blank pores.

[0037] Preferably, the preparation method further comprises: removing dust from the silicon oxide evaporation material.

[0038] Special equipment is used to remove dust from the evaporating material, and the dust on the surface of the particles is removed by air flow at a certain pressure.

[0039] Preferably, the dust removal time is 10-30 min, for example, 10 min, 15 min, 20 min, 25 min or 30 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the particle size of the silicon oxide evaporation material in step (4) is in the range of 2-5 mm, for example, 2 mm, 3 mm, 4 mm or 5 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] As a preferred technical solution of the preparation method provided by the present invention, the preparation method comprises the following steps:

[0042] (1) mixing silicon oxide powder having a purity of ≥99.99% and a D50 particle size of 1-10 μm with a binder and water and then ball milling the mixture, wherein the amount of the binder is 0.5-6 wt % of the silicon oxide powder, the ball milling speed is 30-80 r / min, the ball milling time is ≥12 h, and the ball-to-material mass ratio during ball milling is 1:(3-6), to obtain a mixed powder;

[0043] (2) cold isostatically pressing the mixed powder obtained in step (1) at a pressure of 180-280 MPa for 2-8 minutes to obtain a blank;

[0044] (3) crushing the blank obtained in step (2) to a particle size of 6-10 mm and then sintering, wherein the charge thickness during sintering is less than 15 mm, and the sintering process comprises heating to 200-400° C. at a rate of 5-8° C. / min in an oxygen atmosphere, keeping the temperature for 0.5-2 h, then heating to 1000-1300° C. at a rate of 2-5° C. / min, keeping the temperature for 0.5-2 h, and then heating to 1400-1650° C. at a rate of 1-3° C. / min, keeping the temperature for 10-14 h, and cooling with the furnace to obtain a sintered material;

[0045] (4) The sintered material obtained in step (3) is graded, sieved and dusted for 10-30 minutes to obtain a silicon oxide evaporation material with a particle size range of 2-5 mm.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The silicon oxide evaporation material prepared by the preparation method provided by the present invention has high purity and high density, especially can reach more than 99.0%, uniform particle size, no residue on the surface, and when applied to evaporation, stable performance and good evaporation effect. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0049] In order to clearly illustrate the technical solution of the present invention, the porosity of the silicon oxide evaporation material provided in the embodiment of the present invention is tested to determine its density, the silicon oxide evaporation material is sieved through a sieve of corresponding mesh number to evaluate its particle size distribution uniformity, and whether there is slag on its surface is observed.

[0050] Example 1

[0051] This embodiment provides a method for preparing a silicon oxide evaporation material, the preparation method comprising the following steps:

[0052] (1) High-purity silicon oxide powder with a D50 particle size of 5 μm and a purity of 99.99% was selected, and analytically pure sodium silicate was selected as a binder in an amount of 3 wt % of the silicon oxide powder. The silicon oxide powder, the binder and pure water containing 10 wt % of the silicon oxide powder were put into a ball mill and ball milled at a speed of 50 r / min. The ball-to-material mass ratio during ball milling was 1:5. The ball milling was performed for 15 h. After the ball milling was completed, the mixed powder was taken out;

[0053] (2) putting the mixed powder obtained in step (1) into a rubber sleeve for cold isostatic pressing at a pressure of 250 MPa for a holding time of 5 min. After the cold isostatic pressing is completed, taking out the blank;

[0054] (3) The blank obtained in step (2) is placed in a ceramic-lined jaw crusher for crushing to a particle size of 6-10 mm, and the crushed particles are loaded into an alumina crucible with a loading thickness of 12 mm. The crucible is placed in an oxygen atmosphere sintering furnace, and the temperature is first increased to 300° C. at a rate of 6° C. / min, and kept warm for 1 h, then increased to 1200° C. at a rate of 4° C. / min, and kept warm for 1 h, and finally increased to 1500° C. at a rate of 2° C. / min, and kept warm for 12 h. After the insulation is completed, the crucible and the sintered material are taken out after cooling to room temperature with the furnace;

[0055] (4) The sintered material obtained in step (3) is graded and sieved, and dust is removed for 20 minutes to obtain a silicon oxide evaporation material with a particle size range of 2-5 mm.

[0056] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0057] Example 2

[0058] This embodiment provides a method for preparing a silicon oxide evaporation material, the preparation method comprising the following steps:

[0059] (1) High-purity silicon oxide powder with a D50 particle size of 10 μm and a purity of 99.99% was selected, and analytically pure polyvinyl alcohol was selected as a binder in an amount of 0.5 wt % of the silicon oxide powder. The silicon oxide powder, the binder and pure water containing 10 wt % of the silicon oxide powder were put into a ball mill and ball milled at a speed of 80 r / min. The ball-to-material mass ratio during ball milling was 1:6. The ball milling was performed for 12 h. After the ball milling was completed, the mixed powder was taken out;

[0060] (2) putting the mixed powder obtained in step (1) into a rubber sleeve for cold isostatic pressing at a pressure of 180 MPa for a holding time of 8 min. After the cold isostatic pressing is completed, taking out the blank;

[0061] (3) The blank obtained in step (2) is placed in a ceramic-lined jaw crusher for crushing to a particle size of 6-10 mm, and the crushed particles are loaded into an alumina crucible with a loading thickness of 14 mm. The crucible is placed in an oxygen atmosphere sintering furnace, and the temperature is first increased to 200° C. at a rate of 5° C. / min, and kept at this temperature for 2 h, then increased to 1000° C. at a rate of 2° C. / min, and kept at this temperature for 2 h, and finally increased to 1400° C. at a rate of 1° C. / min, and kept at this temperature for 14 h. After the insulation is completed, the crucible and the sintered material are taken out after cooling to room temperature with the furnace;

[0062] (4) The sintered material obtained in step (3) is graded and sieved, and dust is removed for 10 minutes to obtain a silicon oxide evaporation material with a particle size range of 2-5 mm.

[0063] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0064] Example 3

[0065] This embodiment provides a method for preparing a silicon oxide evaporation material, the preparation method comprising the following steps:

[0066] (1) High-purity silicon oxide powder with a D50 particle size of 1 μm and a purity of 99.99% was selected, and analytically pure polyvinyl alcohol was selected as a binder in an amount of 6 wt % of the silicon oxide powder. The silicon oxide powder, the binder and pure water containing 10 wt % of the silicon oxide powder were put into a ball mill and ball milled at a speed of 30 r / min. The ball-to-material mass ratio during ball milling was 1:3. The ball milling was performed for 20 h. After the ball milling was completed, the mixed powder was taken out;

[0067] (2) putting the mixed powder obtained in step (1) into a rubber sleeve for cold isostatic pressing at a pressure of 280 MPa for a holding time of 2 min. After the cold isostatic pressing is completed, taking out the blank;

[0068] (3) The blank obtained in step (2) is placed in a ceramic-lined jaw crusher for crushing to a particle size of 6-10 mm, and the crushed particles are loaded into an alumina crucible with a loading thickness of 14 mm. The crucible is placed in an oxygen atmosphere sintering furnace, and the temperature is first increased to 400° C. at a rate of 8° C. / min, and kept at this temperature for 0.5 h, then increased to 1300° C. at a rate of 5° C. / min, and kept at this temperature for 0.5 h, and finally increased to 1650° C. at a rate of 3° C. / min, and kept at this temperature for 10 h. After the insulation is completed, the crucible and the sintered material are taken out after cooling to room temperature with the furnace;

[0069] (4) The sintered material obtained in step (3) is graded and sieved, and dust is removed for 30 minutes to obtain a silicon oxide evaporation material with a particle size range of 2-5 mm.

[0070] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0071] Example 4

[0072] This embodiment provides a method for preparing a silicon oxide evaporation material. Compared with Embodiment 1, the pressure of the cold isostatic pressing in step (2) is controlled to be 150 MPa, and the rest is the same as Embodiment 1.

[0073] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0074] Example 5

[0075] This embodiment provides a method for preparing a silicon oxide evaporation material. Compared with Embodiment 1, the pressure of the cold isostatic pressing in step (2) is controlled to be 300 MPa, and the rest is the same as Embodiment 1.

[0076] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0077] Example 6

[0078] This embodiment provides a method for preparing a silicon oxide evaporation material. Compared with Embodiment 1, the sintering temperature in step (3) is always controlled to be 1500° C., and the rest is the same as Embodiment 1.

[0079] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0080] Example 7

[0081] This embodiment provides a method for preparing a silicon oxide evaporation material. Compared with Embodiment 1, the third sintering temperature in step (3) is controlled to be 1300° C., and the rest is the same as Embodiment 1.

[0082] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0083] Example 8

[0084] This embodiment provides a method for preparing a silicon oxide evaporation material. Compared with Embodiment 1, the third sintering temperature in step (3) is controlled to be 1800° C., and the rest is the same as Embodiment 1.

[0085] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0086] Example 9

[0087] This embodiment provides a method for preparing a silicon oxide evaporation material. Compared with Embodiment 1, dust removal is not performed, and the rest is the same as Embodiment 1.

[0088] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0089] Comparative Example 1

[0090] This comparative example provides a method for preparing a silicon oxide evaporation material. Compared with Example 1, the cold isostatic pressing in step (2) is not performed, and the rest is the same as Example 1.

[0091] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0092] Comparative Example 2

[0093] This comparative example provides a method for preparing a silicon oxide evaporation material. Compared with Example 1, the sintering in step (3) is not performed, and the rest is the same as Example 1.

[0094] The test results of the silicon oxide evaporation material prepared in this example are listed in Table 1.

[0095] Table 1

[0096] Density(%) Particle size distribution uniformity Whether there is residue on the surface Example 1 99.5 Uniform No residue Example 2 99.0 Uniform No residue Example 3 99.7 Uniform No residue Example 4 98.2 Uniform There is slag Example 5 99.4 Uneven No residue Example 6 99.5 Uneven No residue Example 7 97.0 Uneven There is slag Example 8 - - - Example 9 99.3 Uniform There is slag Comparative Example 1 81.6 Uneven There is slag Comparative Example 2 58.9 No shape There is slag

[0097] “-” in the table means no data.

[0098] It can be seen from Table 1 that:

[0099] The silicon oxide evaporation material provided in Examples 1-3 of the present invention has good density, which is above 99.0%, and has uniform particle size distribution, no slag on the surface, good evaporation material quality, and good evaporation effect. Compared with Example 1, in Example 4, when the pressure of cold isostatic pressing is too low, it is difficult to achieve the densification effect, and its density decreases. In Example 5, when the pressure of cold isostatic pressing is too high, the particles are too large and the uniformity is poor. In Example 6, sintering is always carried out at a relatively high temperature, which makes the particles too large and uneven. In Example 7, when the third sintering temperature is too low, it is difficult to achieve further densification, and the density and uniformity are both reduced. In Example 8, when the third sintering temperature is too high, the evaporation material will melt and cannot be used. In Example 9, if dust removal is not performed, the evaporation material will contain too much slag and reduce the performance. Compared with Example 1, the density and uniformity of Comparative Example 1 and Comparative Example 2 are significantly reduced, indicating that the cold isostatic pressing and sintering processes synergistically improve the performance of the evaporation material, and neither is indispensable.

[0100] In summary, the silicon oxide evaporation material prepared by the preparation method provided by the present invention has high purity and high density, especially reaching more than 99.0%, uniform particle size, and no residue on the surface. When used for evaporation, it has stable performance and good evaporation effect.

[0101] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a silicon oxide evaporation material, characterized in that: The preparation method comprises the following steps: (1) mixing silicon oxide powder and a binder and then ball milling to obtain a mixed powder; (2) cold isostatically pressing the mixed powder obtained in step (1) to obtain a blank; The cold isostatic pressing pressure is 180-280 MPa, and the cold isostatic pressing time is 2-8 min; (3) crushing the blank obtained in step (2) and then sintering it to obtain a sintered material; The end point of the pulverization is that the particle size range of the particles is 6-10 mm; The sintering charge thickness is less than 15 mm; the sintering consists of a first sintering, a second sintering and a third sintering performed in sequence; the sintering heating rate is 1-8°C / min; The first sintering temperature is 200-400° C., the first sintering time is 0.5-2 hours, the second sintering temperature is 1000-1300° C., the second sintering time is 0.5-2 hours, the third sintering temperature is 1400-1650° C., the third sintering time is 10-14 hours; (4) The sintered material obtained in step (3) is graded and sieved to obtain a silicon oxide evaporation material with a particle size range of 2-5 mm.

2. The preparation method according to claim 1, characterized in that: The purity of the silicon oxide powder in step (1) is ≥99.99%.

3. The preparation method according to claim 1, characterized in that: The D50 particle size of the silicon oxide powder in step (1) is 1-10 μm.

4. The preparation method according to claim 1, characterized in that: The binder in step (1) includes sodium silicate and / or polyvinyl alcohol.

5. The preparation method according to claim 1, characterized in that: The amount of the binder used in step (1) is 0.5-6wt% of the silicon oxide powder.

6. The preparation method according to claim 1, characterized in that: The mass ratio of ball to material in the ball milling of step (1) is 1:(3-6).

7. The preparation method according to claim 1, characterized in that: The rotation speed of the ball mill in step (1) is 30-80 r / min.

8. The preparation method according to claim 1, characterized in that: The ball milling time in step (1) is ≥12h.

9. The preparation method according to claim 1, characterized in that: The sintering in step (3) is carried out in an oxygen atmosphere.

10. The preparation method according to claim 1, characterized in that: The preparation method further comprises: removing dust from the silicon oxide evaporation material.

11. The preparation method according to claim 10, characterized in that: The dust removal time is 10-30 minutes.

12. The preparation method according to claim 1, characterized in that: The preparation method comprises the following steps: (1) mixing silicon oxide powder having a purity of ≥99.99% and a D50 particle size of 1-10 μm with a binder and water and then ball milling the mixture, wherein the amount of the binder is 0.5-6 wt % of the silicon oxide powder, the ball milling speed is 30-80 r / min, the ball milling time is ≥12 h, and the ball-to-material mass ratio during ball milling is 1:(3-6), to obtain a mixed powder; (2) cold isostatically pressing the mixed powder obtained in step (1) at a pressure of 180-280 MPa for 2-8 minutes to obtain a blank; (3) crushing the blank obtained in step (2) to a particle size of 6-10 mm and then sintering, wherein the charge thickness during sintering is less than 15 mm, and the sintering process comprises heating the temperature to 200-400° C. at a rate of 5-8° C. / min in an oxygen atmosphere, keeping the temperature for 0.5-2 h, then heating the temperature to 1000-1300° C. at a rate of 2-5° C. / min, keeping the temperature for 0.5-2 h, and then heating the temperature to 1400-1650° C. at a rate of 1-3° C. / min, keeping the temperature for 10-14 h, and cooling the temperature in the furnace to obtain a sintered material; (4) The sintered material obtained in step (3) is graded, sieved and dusted for 10-30 minutes to obtain a silicon oxide evaporation material with a particle size range of 2-5 mm.