Method for moisture-proof treatment of quartz composite material and application thereof

Abstract

The present application relates to the field of material surface modification and functional protection, and particularly relates to a high-efficiency moisture-proof treatment method for quartz composite material and application thereof. The method adopts vacuum-assisted pretreatment combined with chemical vapor deposition (CVD) technology, uses tetraethyl orthosilicate (TEOS) as a precursor, and in-situ deposits silicon dioxide (SiO2) on the surface and inside the pores of the quartz composite material under the catalysis of ammonia. By accurately controlling the reaction temperature, pressure and time, efficient plugging of the pores and surface hydrophobic modification are realized. The method significantly reduces the specific surface area and moisture absorption rate of the material, improves the hydrophobicity and maintains the dielectric stability, and has good process uniformity and does not affect the wave transmission performance of the material.

Description

Technical Field

[0001] This invention relates to the fields of materials science and surface engineering, specifically to a moisture-proof treatment method for quartz fiber reinforced composite materials. In particular, it uses vacuum-assisted pretreatment combined with chemical vapor deposition technology to achieve in-situ pore sealing and surface hydrophobic modification, thereby improving its dielectric stability and service life in high humidity environments. Background Technology

[0002] Quartz fiber reinforced composites are widely used in key areas such as wave-transparent materials, electronic device packaging, and high-frequency communication equipment due to their low dielectric constant, low loss, and excellent wave transmission properties. However, the high porosity (specific surface area often exceeding 100 m² / g) and the abundance of hydrophilic silanol groups (Si-OH) on the surface formed during the manufacturing process make it highly susceptible to adsorbing moisture from the environment through hydrogen bonds, resulting in a moisture absorption rate of approximately 10%. Moisture absorption significantly degrades the dielectric properties of the material (e.g., dielectric constant shift exceeding 15%), increases dielectric loss, and severely affects the signal transmission efficiency and reliability of devices.

[0003] Traditional moisture-proofing methods mainly fall into two categories: The first is the coating method, such as coating the material surface with silicone resin, polyvinylidene fluoride (PVDF), etc., to form a physical barrier layer. While this method can reduce moisture absorption, the uniformity of the coating is difficult to guarantee; areas that are too thin offer poor protection, while areas that are too thick may impair the material's wave transmission performance. Furthermore, the adhesion and long-term durability of the coating face challenges. The second is the impregnation method, such as using hydrophobic agents like fluorosilanes to chemically modify the material surface. This method mainly achieves hydrophobicity by changing the surface chemical groups, but its effect on sealing internal pores is limited, and the long-term stability of the modified layer is insufficient, easily leading to performance degradation in humid and hot environments (for example, the moisture absorption rate may rebound after 10 days).

[0004] Therefore, developing a moisture-proof treatment method that can penetrate deep into the material, uniformly and efficiently seal pores, impart stable hydrophobic properties to the surface, and not impair the material's intrinsic properties has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a highly efficient, uniform, and durable moisture-proofing method for quartz composite materials. This method combines vacuum-assisted pretreatment with chemical vapor deposition (CVD) technology to generate silica (SiO2) in situ within the material's pores and on its surface. This achieves a physical sealing mechanism of "micropore closure-mesopore reconstruction," while simultaneously improving surface hydrophobicity, thereby significantly reducing the material's moisture absorption rate and ensuring the long-term stability of its dielectric properties.

[0006] A method for moisture-proofing quartz composite materials includes the following steps: Vacuum-assisted pretreatment: Immerse the quartz composite material in a tetraethyl orthosilicate (TEOS) solution and transfer it to a vacuum-capable container or chamber. Evacuate to a negative pressure (e.g., 0.07-0.09 MPa) and maintain this pressure for a period of time (e.g., 10-60 minutes). This step utilizes negative pressure to expel air from the material's pores, allowing the TEOS solution to penetrate all pores more quickly and thoroughly, laying the foundation for subsequent uniform deposition.

[0007] In-situ deposition: The pretreated material is placed in a CVD reaction chamber, and ammonia catalyst is added. The reaction is carried out under specific temperature, pressure, and time conditions. TEOS undergoes a hydrolysis-condensation reaction under ammonia catalysis, generating SiO2 which is deposited on the inner walls of the pores and the surface of the material. The basic reaction formula is: Si(OC2H5)4 + 2H2O → SiO2 + 4C2H5OH.

[0008] Post-processing: After the reaction is complete, the material is removed and rinsed with anhydrous ethanol to remove unreacted precursors from the surface. Then, it is vacuum dried to thoroughly remove residual ammonia and solvent from the pores.

[0009] The TEOS solution is pure TEOS liquid or its organic solvent dilution. The vacuum degree of the vacuum-assisted pretreatment is 0.07-0.09 MPa, and the treatment time is 10-60 minutes. The organic solvent used in the organic solvent dilution is ethanol or cyclohexane, diluted 1:1 with pure TEOS.

[0010] Furthermore, in step (2), the reaction conditions for chemical vapor deposition are: reaction temperature 20-60℃, cavity pressure 0.07-0.09 MPa, and reaction time 6-48 hours.

[0011] Furthermore, the SiO2 deposited in step (2) exists in the form of microspheres with a diameter of 50-100 nm. Through stacking, the micropores (<2 nm) are blocked and reorganized to form a new mesoporous structure.

[0012] Furthermore, in step (3), the drying is vacuum drying, the drying temperature is 60-100 ℃, and the drying time is 4-8 hours.

[0013] Preferably, the conditions for vacuum-assisted pretreatment in step (1) are: vacuum degree 0.07 MPa and treatment time 30 minutes.

[0014] Preferably, the CVD reaction conditions in step (2) are: temperature 60 ℃, chamber pressure 0.07 MPa, and reaction time 24 hours.

[0015] Preferably, the vacuum drying conditions in step (3) are drying at 80°C for 5 hours.

[0016] This invention also claims protection for quartz composite materials prepared by the above method, wherein the specific surface area is reduced to below 54 m² / g, the moisture absorption rate is reduced to below 0.5%, and the surface water contact angle is greater than 100°. After exposure to an atmospheric environment for 10 days, the rate of change of the real part of its dielectric constant is less than 5%.

[0017] The quartz composite material treated using the above method exhibits a significant reduction in specific surface area from over 100 m² / g to 53.98 m² / g (a decrease of 61.7%), and a substantial decrease in moisture absorption from approximately 10% to 0.41% (a decrease of 94.5%). The water contact angle on the material surface increases from 43.2° in the hydrophilic state to 102.7° in the hydrophobic state. After 10 days of exposure to atmospheric conditions, the rate of change of the real part of its dielectric constant is only 3.53%, demonstrating excellent dielectric stability.

[0018] The present invention also claims protection for the quartz composite material with low moisture absorption, high hydrophobicity and high dielectric stability obtained by the above method, and its application in the fields of wave-transparent components and electronic packaging. Attached Figure Description

[0019] Figure 1 A diagram of the vapor deposition apparatus used in the moisture-proof treatment method of this invention.

[0020] Figure 2 Optical images of quartz composite material after vapor deposition in the embodiments of the present invention, wherein (a) to (e) are at room temperature for 6 h, 12 h, 24 h, 40 ℃, 24 h, and 60 ℃, 24 h respectively, corresponding to Examples 1-5.

[0021] Figure 3 Example 1 of the present invention (room temperature treatment for 6 hours) Figure 3 a and Figure 3 b) and 5 (treatment at 60 ℃ for 24 h) Figure 3 c and Figure 3 d) Scanning electron microscope image.

[0022] Figure 4 The changes in moisture absorption rate of quartz composite materials before and after vapor deposition treatment under different conditions in the embodiments of the present invention, wherein RT, 6 h, RT, 12 h, RT, 24 h, 40 ℃, 24 h, and 60 ℃, 24 h correspond to Examples 1-5, respectively.

[0023] Figure 5 The BET adsorption-desorption curves of quartz composite materials before and after vapor deposition treatment under different conditions in the embodiments of the present invention are as follows: (a) without CVD treatment; (b) after CVD treatment at room temperature for 6 h, corresponding to Example 1; (c) after CVD treatment at 40 °C for 24 h, corresponding to Example 4.

[0024] Figure 6 The following are adsorption pore size distribution diagrams of quartz composite materials before and after vapor deposition treatment under different conditions in the embodiments of the present invention: (a) cumulative pore volume; (b) dV / dD pore size distribution; (c) dV / dlogD pore size distribution. RT, 6 h, 40 ℃, 24 h correspond to Examples 1 and 4, respectively.

[0025] Figure 7 The dielectric properties of quartz composite materials before and after vapor deposition treatment in the embodiments of the present invention are shown in (a) real part of dielectric constant; (c) imaginary part of dielectric constant; (d) dielectric loss, RT, 6 h, 40 ℃, 24 h correspond to Examples 1 and 4, respectively. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Example 1

[0027] Take a 15 cm × 1.5 cm × 1.5 cm quartz fiber reinforced composite material sample and immerse it in pure TEOS liquid, ensuring the TEOS completely covers the sample. Place the container containing the sample and TEOS into a vacuum chamber, evacuate to a pressure of 0.07 MPa, and maintain this vacuum for 30 minutes. Then restore normal pressure and remove the sample. Place the pretreated sample on a polytetrafluoroethylene support plate inside the CVD reaction chamber. Add 50 mL of 25% ammonia solution to the chamber. The specific apparatus used for the reaction is as follows: Figure 1 As shown. The reaction chamber was sealed, and the vacuum pump was turned on to maintain the pressure inside the chamber at 0.07 MPa. The reaction was continued under these conditions for 6 hours. After the reaction was completed, the chamber was allowed to cool to room temperature, and the sample was removed. The sample surface was rinsed three times repeatedly with anhydrous ethanol to remove residues. The sample was then placed in a vacuum drying oven and dried at 80°C and a vacuum of 0.05 MPa for 5 hours to remove ammonia gas from the internal pores, resulting in a moisture-proof quartz composite material, as shown. Figure 2 As shown. A sealed space was constructed using an air humidifier and a storage box. The rate of water vapor generation was adjusted, and the temperature and humidity of the space were monitored using a thermometer and hygrometer to maintain it at 15 ℃ and 70% humidity. The sample was placed in this space for 12 hours. The moisture absorption rate was calculated by measuring the weight gain of the sample using an electronic balance. Figure 4 As shown, the moisture absorption rate is 1.92%. Example 2

[0028] Take a 15 cm × 1.5 cm × 1.5 cm quartz fiber reinforced composite material sample and immerse it in pure TEOS liquid, ensuring the TEOS completely covers the sample. Place the container containing the sample and TEOS into a vacuum chamber, evacuate to a pressure of 0.07 MPa, and maintain this vacuum for 30 minutes. Then restore normal pressure and remove the sample. Place the pretreated sample on a polytetrafluoroethylene support plate inside the CVD reaction chamber. Add 50 mL of 25% ammonia solution to the chamber. The specific apparatus used for the reaction is as follows: Figure 1 As shown. The reaction chamber was sealed, and the vacuum pump was turned on to maintain the pressure inside the chamber at 0.07 MPa. The reaction was continued under these conditions for 12 hours. After the reaction was complete, the chamber was allowed to cool to room temperature, and the sample was removed. The sample surface was rinsed three times repeatedly with anhydrous ethanol to remove residues. The sample was then placed in a vacuum drying oven and dried at 80°C and a vacuum of 0.05 MPa for 5 hours to remove ammonia gas from the internal pores, resulting in a moisture-proof quartz composite material, as shown. Figure 2 As shown. A sealed space was constructed using an air humidifier and a storage box. The rate of water vapor generation was adjusted, and the temperature and humidity of the space were monitored using a thermometer and hygrometer to maintain it at 15 ℃ and 70% humidity. The sample was placed in this space for 12 hours. The moisture absorption rate was calculated by measuring the weight gain of the sample using an electronic balance. Figure 4 As shown, the moisture absorption rate is 1.26%. Example 3

[0029] Take a 15 cm × 1.5 cm × 1.5 cm quartz fiber reinforced composite material sample and immerse it in pure TEOS liquid, ensuring the TEOS completely covers the sample. Place the container containing the sample and TEOS into a vacuum chamber, evacuate to a pressure of 0.07 MPa, and maintain this vacuum for 30 minutes. Then restore normal pressure and remove the sample. Place the pretreated sample on a polytetrafluoroethylene support plate inside the CVD reaction chamber. Add 50 mL of 25% ammonia solution to the chamber. The specific apparatus used for the reaction is as follows: Figure 1 As shown. The reaction chamber was sealed, and the vacuum pump was turned on to maintain the pressure inside the chamber at 0.07 MPa. The reaction was continued under these conditions for 24 hours. After the reaction was completed, the chamber was allowed to cool to room temperature, and the sample was removed. The sample surface was rinsed three times repeatedly with anhydrous ethanol to remove residues. The sample was then placed in a vacuum drying oven and dried for 5 hours at 80°C and a vacuum of 0.05 MPa to remove ammonia gas from the internal pores, resulting in a moisture-proof quartz composite material, as shown. Figure 2 As shown. A sealed space was constructed using an air humidifier and a storage box. The rate of water vapor generation was adjusted, and the temperature and humidity of the space were monitored using a thermometer and hygrometer to maintain it at 15 ℃ and 70% humidity. The sample was placed in this space for 12 hours. The moisture absorption rate was calculated by measuring the weight gain of the sample using an electronic balance. Figure 4 As shown, the moisture absorption rate is 0.78%. Example 4

[0030] Take a 15 cm × 1.5 cm × 1.5 cm quartz fiber reinforced composite material sample and immerse it in pure TEOS liquid, ensuring the TEOS completely covers the sample. Place the container containing the sample and TEOS into a vacuum chamber, evacuate to a pressure of 0.07 MPa, and maintain this vacuum for 30 minutes. Then restore normal pressure and remove the sample. Place the pretreated sample on a polytetrafluoroethylene support plate inside the CVD reaction chamber. Add 50 mL of 25% ammonia solution to the chamber. The specific apparatus used for the reaction is as follows: Figure 1 As shown. The reaction chamber was sealed, and the vacuum pump was turned on to maintain the pressure inside the chamber at 0.07 MPa. The heating system was started, raising the reaction temperature to 40℃ and maintaining the reaction under these conditions for 24 hours. After the reaction was completed, the chamber was allowed to cool to room temperature, and the sample was removed. The sample surface was rinsed three times repeatedly with anhydrous ethanol to remove residues. The sample was then placed in a vacuum drying oven and dried for 5 hours at 80℃ and a vacuum of 0.05 MPa to remove ammonia gas from the internal pores, resulting in a moisture-proof quartz composite material, as shown. Figure 2 As shown. A sealed space was constructed using an air humidifier and a storage box. The rate of water vapor generation was adjusted, and the temperature and humidity of the space were monitored using a thermometer and hygrometer to maintain it at 15 ℃ and 70% humidity. The sample was placed in this space for 12 hours. The moisture absorption rate was calculated by measuring the weight gain of the sample using an electronic balance. Figure 4 As shown, the moisture absorption rate is 0.63%. Example 5

[0031] Take a 15 cm × 1.5 cm × 1.5 cm quartz fiber reinforced composite sample and immerse it in pure TEOS liquid, ensuring the TEOS completely covers the sample. Place the container containing the sample and TEOS into a vacuum chamber, evacuate to a pressure of 0.03 MPa, and maintain this vacuum for 30 minutes. Then restore normal pressure and remove the sample. Place the pretreated sample on a polytetrafluoroethylene support plate inside the CVD reaction chamber. Add 50 mL of 25% ammonia solution to the chamber. The specific apparatus used for the reaction is as follows: Figure 1 As shown. The reaction chamber was sealed, and the vacuum pump was turned on to maintain the pressure inside the chamber at 0.03 MPa. The heating system was started, raising the reaction temperature to 60℃ and maintaining the reaction under these conditions for 24 hours. After the reaction was completed, the chamber was allowed to cool to room temperature, and the sample was removed. The sample surface was rinsed three times repeatedly with anhydrous ethanol to remove residues. Then, the sample was placed in a vacuum drying oven and dried for 5 hours at 80℃ and a vacuum of 0.05 MPa to remove ammonia gas from the internal pores, resulting in a moisture-proof quartz composite material, as shown. Figure 2As shown. A sealed space was constructed using an air humidifier and a storage box. The rate of water vapor generation was adjusted, and the temperature and humidity of the space were monitored using a thermometer and hygrometer to maintain it at 15 ℃ and 70% humidity. The sample was placed in this space for 12 hours. The moisture absorption rate was calculated by measuring the weight gain of the sample using an electronic balance. Figure 4 As shown, the moisture absorption rate is 0.41%. Example 6

[0032] Three groups of quartz composite material samples—untreated, Example 1, and Example 4—were subjected to BET testing. Specific surface area and porosity were analyzed using a Micromeritics ASAP 2460 multi-station extended surface area and porosity analyzer. Nitrogen adsorption-desorption isotherm tests were performed on the materials under the following conditions: 1. Sample pretreatment and testing conditions Vacuum degassing: Place the sample in the analysis station and degas continuously at 200 ℃ for 8 hours to achieve a vacuum degree <10⁻³Torr, ensuring complete removal of surface physically adsorbed impurities; Adsorption medium: High-purity liquid nitrogen (77 K) is used as the cold trap, and ultra-dry nitrogen gas (99.999% purity) is used as the adsorbate; Test range: relative pressure (p / p0) covers 0.001~0.995, resolution 0.0001.

[0033] 2. Data Analysis Model Specific surface area calculation: Based on the Brunauer-Emmett-Teller (BET) multilayer adsorption theory, the linear range of relative pressure p / p0 = 0.05~0.35 when the monolayer saturation adsorption capacity is reached is selected for fitting. Pore ​​size distribution analysis: The Barrett-Joyner-Halenda (BJH) model was used to analyze the mesopore distribution in the 2–50 nm range; Total pore volume determination: The capacity of the material's open pore structure is characterized by the maximum adsorption amount calculated when p / p0=0.995.

[0034] The BET test results are shown in the table below. Figure 5 As shown:

[0035] The BJH adsorption pore size distribution showed that, with increasing treatment conditions, the pore size distribution peak shifted to the right from the <2 nm range to the 3–8 nm range, and the peak height decreased significantly. Specific results are shown below. Figure 6 As shown.

[0036] Example 7 Two groups of quartz composite material samples, from Examples 1 and 4, were used to study the effect of CVD process on the intrinsic dielectric properties of the materials. Both groups of samples were exposed to the atmosphere for 10 days to simulate the actual moisture absorption process. The dielectric properties were tested using a vector network analyzer in the X-band (8.2-12.4 GHz).

[0037] Test results show that the average rate of change of the real part of the dielectric constant (ε') of the sample is 3.53%, and the dielectric loss (tanδ) is... ε The average change rate was 9.37%, which is well within the range of dielectric property differences caused by varying moisture absorption. This indicates that the fluctuation in dielectric properties is entirely caused by differences in moisture absorption, and the CVD process itself did not alter the intrinsic dielectric properties of the material, ensuring the stability of the wave transmission performance after moisture-proof modification. Specific results are as follows: Figure 7 As shown.

[0038] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for moisture-proofing quartz composite materials, characterized in that, Includes the following steps: (1) Vacuum-assisted pretreatment: The quartz composite material is immersed in tetraethyl orthosilicate (TEOS) solution and treated in a vacuum environment to allow the precursor to fully penetrate the pores of the material; (2) In-situ deposition: The pretreated material is placed in the chemical vapor deposition (CVD) reaction chamber, and ammonia is added as a catalyst. The reaction is carried out under vacuum conditions, so that TEOS is hydrolyzed to generate SiO2 and deposited on the surface and pores of the material.

2. The moisture-proof treatment method according to claim 1, characterized in that, In step (1), the TEOS solution is pure TEOS liquid or its organic solvent dilution, the vacuum degree of the vacuum environment for vacuum-assisted pretreatment is 0.07-0.09 MPa, and the treatment time is 10-60 minutes.

3. The moisture-proof treatment method according to claim 1, characterized in that, In step (2), the reaction conditions for in-situ deposition are: reaction temperature 20-60℃, cavity pressure 0.07-0.09 MPa, and reaction time 6-48 hours.

4. The moisture-proof treatment method according to claim 3, characterized in that, In step (2), the reaction temperature is 60℃, the chamber pressure is 0.07 MPa, and the reaction time is 24 hours.

5. The moisture-proof treatment method according to claim 1, characterized in that, The SiO2 deposited in step (2) exists in the form of microspheres with a diameter of 50-100 nm. Through stacking, it blocks the <2 nm micropores and reorganizes them to form a new mesoporous structure.

6. The moisture-proof treatment method according to claim 1, characterized in that, It also includes step (3) post-treatment: after the reaction is completed, the material is taken out, rinsed with anhydrous ethanol to remove surface residues, and then dried; the drying is vacuum drying, the drying temperature is 60-100℃, and the drying time is 4-8 hours.

7. A quartz composite material treated by the method according to any one of claims 1-6, characterized in that, Its specific surface area is reduced to below 54 m² / g, its moisture absorption rate is reduced to below 0.5%, and its surface water contact angle is greater than 100°.

8. The quartz composite material according to claim 7, characterized in that, After being exposed to the atmosphere for 10 days, the rate of change of the real part of its dielectric constant is less than 5%.

9. The application of a quartz composite material as described in claim 7 or 8 in wave-transparent materials, electronic device packaging, or high-frequency communication equipment.

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