Method for improving bending strength of phosphate glass through citric acid corrosion

Abstract

The invention belongs to the technical field of glass strengthening, and particularly relates to a method for improving the bending strength of phosphate glass through citric acid corrosion, which comprises the following steps: S1, coating a UV film: coating a waterproof UV film on a single non-laser cutting surface of phosphate glass, and fixing the phosphate glass on a flange plate; s2, preparing a citric acid aqueous solution, wherein the mass fraction of citric acid monohydrate in the solution is 13-20wt%, stirring the citric acid monohydrate in pure water until the citric acid monohydrate is completely dissolved, and pouring the citric acid monohydrate into a corrosion vessel; s3, corrosion strengthening is conducted, specifically, a vessel containing a corrosion solution is placed in a water bath kettle, the water bath temperature is 40-60 DEG C, after the solution temperature is stable, the whole flange plate is immersed in a citric acid solution, and after standing is conducted for 2-7 min, the flange plate is taken out; and S4, cleaning and air drying are conducted, specifically, after the phosphate glass is subjected to double-face scrubbing in a water tank for 2 min, an ion cleaning machine is used for cleaning and spin-drying the glass for 5 min, and then the glass is put into an ion fan to be blow-dried for 15 min. The method has the advantages that the citric acid solution plays a role in passivating microcracks generated by laser cutting of the phosphate glass, so that the bending strength of the phosphate glass is greatly improved, the corrosion strengthening effect is stable, and meanwhile, the surface corrosion defect cannot be caused.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphate glass strengthening for mobile phone filters, and specifically, is a method for improving the bending strength of phosphate glass by citric acid corrosion. Background Art

[0002] Phosphate glass has broad application prospects in the fields of optics, laser technology, and semiconductors due to its ultraviolet transparency, low dispersion, moderate phonon energy, high solubility for rare earth ions, good spectral properties of rare earth ions, and small nonlinear coefficient.

[0003] During the picosecond laser cutting process of phosphate glass and glass fragments, microcracks are inevitably generated in the upper and lower areas of the laser modified layer, which greatly reduces the mechanical strength of the glass. Acid etching can passivate microcracks and slow down the stress concentration effect at the crack tip, thereby preventing the microcracks from further expanding. The acid solutions such as HF, H2SO4, and HClO4 used in previous studies react violently with phosphate glass, which can easily cause excessive corrosion, surface defects, and reduced transmittance. At the same time, strong acids have a high degree of ionization, and in actual production processes, the solution H + Continuous consumption causes the corrosion strengthening effect to be unstable.

[0004] To this end, the present invention provides a method for improving the bending strength of phosphate glass by citric acid corrosion. Summary of the invention

[0005] In order to make up for the shortcomings of the existing technology, a method for improving the flexural strength of phosphate glass by citric acid corrosion is proposed. By adjusting the citric acid concentration and corrosion time at a certain reaction temperature, the flexural strength of phosphate glass is greatly improved without causing surface corrosion defects.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for improving the bending strength of phosphate glass by citric acid corrosion, the method specifically comprises the following steps:

[0008] S1. UV coating: Phosphate glass is coated with UV film and fixed on the flange;

[0009] S2. Prepare a solution: add solid citric acid monohydrate particles into pure water to prepare a citric acid monohydrate solution with a mass fraction of 13wt%-20wt%, stir until completely dissolved and then pour into a corrosion container;

[0010] S3, corrosion strengthening: After the citric acid solution is heated in a water bath until the temperature is stable, immerse the entire flange in the citric acid solution;

[0011] S4. Clean and air dry: Take out the flange and place it in the sink, scrub the phosphate glass on both sides, use an ion cleaner to clean and dry the glass, and then put it in an ion blower to dry it.

[0012] Preferably, the surface covered with the UV film in S1 is the surface not irradiated by the laser during laser cutting.

[0013] Preferably, a waterproof UV film with a thickness of 0.15 mm is used in S1.

[0014] Preferably, the mass fraction of the citric acid monohydrate solution in S2 is 13wt%-20wt%.

[0015] Preferably, the water bath heating temperature of the solution in S3 is 40-60°C.

[0016] Preferably, the phosphate glass corrosion time in S3 is 2-7 minutes.

[0017] Preferably, in S4, the glass brushing time is 2 minutes, the cleaning and drying time is 5 minutes, and the drying time in the ion blower is 15 minutes.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The method of improving the flexural strength of phosphate glass by citric acid corrosion described in the present invention increases the flexural strength of phosphate glass by 3-6 times by adjusting the citric acid concentration and corrosion time at a certain reaction temperature.

[0020] 2. The citric acid corrosion of the present invention improves the bending strength of phosphate glass. The citric acid with weak ionization degree is used as the corrosion material, which can reduce corrosion defects such as pits. Meanwhile, H + The strengthening effect is stable and has important significance for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] Figure 1 is a SEM image of the phosphate glass surface obtained in Example 7;

[0023] Figure 2 is a SEM image of the phosphate glass surface obtained in Example 9;

[0024] Figure 3 This is a SEM image of the phosphate glass surface obtained in Example 10. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Specific examples are given below.

[0027] Example 1: This example 1 provides a method for improving the bending strength of phosphate glass by citric acid corrosion, and the specific steps of the method are as follows:

[0028] S1. UV coating: Phosphate glass is coated with UV film and fixed on the flange;

[0029] Note: Fixing the glass on the flange with UV film for etching can avoid defects such as edge collapse caused by manual handling. At the same time, microcracks on the glass surface are inevitably damaged during laser cutting, so the non-laser irradiated surface is covered to expose the surface with large-sized microcracks to corrode and passivate the microcracks.

[0030] S2. Prepare a solution: add solid citric acid monohydrate particles into pure water to prepare a citric acid monohydrate solution with a mass fraction of 20 wt%, stir until completely dissolved and then pour into a corrosion container;

[0031] S3, corrosion strengthening: After the citric acid solution is heated to 40°C in a water bath, the entire flange is immersed in the citric acid solution and corroded for 5 minutes before being taken out;

[0032] Note: Citric acid has a low degree of ionization, and water bath heating can effectively increase the reaction rate and shorten the corrosion time.

[0033] S4. Clean and air-dry: Take out the flange and place it in the sink. Brush the phosphate glass on both sides for 2 minutes. Clean and spin-dry in an ion cleaner for 5 minutes. Then put it in an ion blower for 15 minutes to dry.

[0034] Scanning electron microscope examination shows that the phosphate glass obtained by corrosion strengthening in Example 1 has no corrosion pits, delamination and other defects, and the bending stress is tested to be σ (MPa).

[0035] Example 2: The coated phosphate glass was immersed in a 20wt% citric acid monohydrate solution at a constant temperature of 50°C for 5 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy to find no corrosion pits, delamination and other defects, and the bending stress was tested to be σ (MPa).

[0036] Example 3: The coated phosphate glass was immersed in a 20wt% citric acid monohydrate solution at a constant temperature of 60°C for 5 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy to find no corrosion pits, delamination and other defects, and the bending stress was tested to be σ (MPa).

[0037] Example 4: The coated phosphate glass was immersed in a 16.7wt% citric acid monohydrate solution at a constant temperature of 50°C for 5 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy to find no defects such as corrosion pits and delamination, and the bending stress was tested to be σ (MPa).

[0038] Example 5: The coated phosphate glass was immersed in a 13wt% citric acid monohydrate solution at a constant temperature of 50°C for 5 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy to find no corrosion pits, delamination and other defects, and the bending stress was tested to be σ (MPa).

[0039] Example 6: The coated phosphate glass was immersed in a 13wt% citric acid monohydrate solution at a constant temperature of 50°C for 7 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy to find no defects such as corrosion pits and delamination, and the bending stress was tested to be σ (MPa).

[0040] Example 7: The coated phosphate glass was immersed in a 13wt% citric acid monohydrate solution at a constant temperature of 50°C for 3 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy and no corrosion pits, delamination or other defects were found. Figure 1 , and the bending stress is tested as σ (MPa).

[0041] Example 8: The coated phosphate glass was immersed in a 13wt% citric acid monohydrate solution at a constant temperature of 50°C for 2 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy to find no corrosion pits, delamination and other defects, and the bending stress was tested to be σ (MPa).

[0042] Comparative Example 1: The bending stress of the unstrengthened phosphate glass was tested to be σ (MPa).

[0043] Comparative Example 2: The coated phosphate glass was immersed in an unheated 3wt% HF solution for 2 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy and pits were found on the surface of the glass. Figure 2 .

[0044] Comparative Example 3: The coated phosphate glass was immersed in an unheated BOE solution (3.3wt% HF + 38wt% NH4F) for 2 minutes, the glass was taken out and scrubbed on both sides for 2 minutes, cleaned and dried in an ion cleaner for 5 minutes, and then dried in an ion blower for 15 minutes. The appearance was inspected by scanning electron microscopy and pits were found on the surface of the glass. Figure 3 .

[0045] The number of samples in the above-mentioned embodiments 1-8 and comparative example 1 is 12 respectively, and the bending stress values ​​σ (MPa) tested and recorded are shown in Table 1.

[0046] Table 1

[0047]

[0048] By comparing the average and minimum bending stress values ​​of the samples in the above examples, it is found that after corrosion and strengthening with citric acid solution, the bending stress of phosphate glass is improved. The average bending stress value of Example 7 is improved most significantly, which is 3 times that of the unstrengthened sample; the minimum bending stress value of Example 8 is improved most significantly, which is 6 times that of the unstrengthened sample.

[0049] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for improving the bending resistance of phosphate glass by citric acid corrosion, characterized in that: The specific steps of this method are as follows: S1: UV coating: Phosphate glass is coated with UV film and fixed on the flange; S2: preparing a solution: adding solid citric acid monohydrate particles to pure water to prepare a citric acid monohydrate solution with a mass fraction of 13wt%-20wt%, stirring until completely dissolved and then pouring into a corrosion vessel; S3: Corrosion strengthening: After the citric acid solution is heated in a water bath until the temperature is stable, the entire flange is immersed in the citric acid solution; S4: Cleaning and air drying: Take out the flange and place it in the sink, scrub the phosphate glass on both sides, use an ion cleaner to clean and dry the glass, and then put it into an ion blower to dry it.

2. The method for improving the bending strength of phosphate glass by citric acid corrosion according to claim 1, characterized in that: The surface covered with UV film in S1 is the surface not irradiated by laser during laser cutting.

3. The method for improving the bending strength of phosphate glass by citric acid corrosion according to claim 1, characterized in that: The S1 uses a 0.15mm thick waterproof UV film, which can balance protection and operational convenience and avoid penetration of corrosive liquids.

4. The method for improving the bending strength of phosphate glass by citric acid corrosion according to claim 1, characterized in that: The mass fraction of the citric acid monohydrate solution in S2 is 13wt%-20wt%.

5. The method for improving the bending strength of phosphate glass by citric acid corrosion according to claim 1, characterized in that: The water bath heating temperature of the solution in S3 is 40-60°C.

6. The method for improving the bending strength of phosphate glass by citric acid corrosion according to claim 1, characterized in that: The phosphate glass corrosion time in S3 is 2-7 minutes.

7. The method for improving the bending strength of phosphate glass by citric acid corrosion according to claim 1, characterized in that: In S4, the glass brushing time is 2 minutes, the cleaning and drying time is 5 minutes, and the ion fan drying time is 15 minutes.

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