Preparation process of phosphate glass with low hydroxyl content and high uniformity

Abstract

The invention discloses a preparation process of phosphate glass with low hydroxyl content and high uniformity. A secondary melting process is mainly adopted, uniform and bubble-free phosphate glass is obtained through high-temperature melting, glass dewatering is performed through secondary in-tube atmosphere low-temperature melting, and free forming of the glass in a furnace is performed by adopting a crucible which is not mutually wetted with the glass to reduce glass pouring stripes. In the process, the volatilization of the components is reduced by using a lower secondary melting temperature, the water removal of the glass is performed by introducing gas, and meanwhile, the glass is freely formed in the crucible by adopting the crucible which is not moistened with the molten glass, so that the pouring stripes of the glass are reduced, and the optical uniformity of the glass is improved.

Description

Technical Field

[0001] The invention relates to a process for preparing optical glass, in particular to a process for preparing phosphate glass with low hydroxyl content and high uniformity. Background Art

[0002] Rare earth doped phosphate glass has high optical gain, small nonlinear coefficient, and good physical and chemical properties, and is widely used in high-power solid and fiber lasers. The phosphate glass matrix is ​​hygroscopic and easy to absorb water during the melting process, resulting in a high hydroxyl content in the phosphate glass matrix, which seriously affects the optical properties of rare earth ions and the physical and chemical properties of the glass. In order to reduce the hydroxyl content in the glass matrix, the traditional method uses a dehydrating agent such as CCl4, SOCl2 and POCl3 to react with the hydroxyl group to generate gas during the glass melting process, and the gas is discharged from the glass liquid at high temperature, thereby realizing the preparation of phosphate glass with low hydroxyl content. The chemical vapor reaction method can be used to prepare phosphate glass with low hydroxyl content, but there are two problems in the dehydration process: one is that it is easy to cause serious volatilization of components in the phosphate glass; the other is that the generated gas is toxic, causing environmental pollution.

[0003] Phosphate glass is generally formed by casting, which is done by melting at high temperature to obtain transparent glass liquid, lowering the temperature of the glass liquid to a suitable temperature, and then pouring the glass liquid into a low-temperature mold. After the glass liquid cools, it forms a block of glass. During casting, due to the low viscosity of the glass liquid, it will flow back and forth in the mold, resulting in casting stripes inside the glass after cooling, causing the optical uniformity of the glass to deteriorate. In order to solve the casting stripes, the casting process needs to be strictly controlled.

[0004] In view of the above problems, the present invention proposes a novel phosphate glass dehydration and molding process to solve the problems of environmental pollution and component volatilization caused by the traditional dehydration process, and poor optical uniformity caused by casting and molding, thereby realizing the preparation of phosphate glass with low hydroxyl content and high optical uniformity. Utility Model Content

[0005] The technical solution of the present invention is as follows: A process for preparing phosphate glass with low hydroxyl content and high optical uniformity comprises the following steps: (1) Raw material processing: weigh the raw materials according to the glass composition and mix them evenly; (2) ball milling the mixed raw materials to further mix the raw materials and ball mill the raw materials into particles with a size of 100 nm to 5 microns; (3) The ball-milled raw material is placed in a crucible for pre-sintering at a temperature of 120-200 degrees to completely eliminate free water in the raw material; and 500-700 degrees to fully decompose the carbonate; (4) melting the pre-burned raw materials at a temperature between 1000 and 1400 degrees for 1 to 4 hours, and stirring during the melting process; (5) Rapidly cooling the molten glass to obtain uniform glass; (6) crushing the first melted glass into glass blocks with a particle size of 1-2 mm; (7) placing the glass pieces into a crucible and placing it into a vacuum tube furnace for secondary melting; (8) Evacuate the tube furnace and then introduce nitrogen, argon and oxygen; (9) Perform secondary melting and heating, the temperature of the secondary melting is within 50 degrees above the softening point of the glass, and the heat preservation treatment is performed for 4-8 hours; (10) After the insulation is completed, the heating of the tubular furnace is turned off, and the gas protection is continued to be introduced, and the glass liquid melted by the secondary melting is cooled and annealed with the furnace; (11) When the temperature in the furnace drops to room temperature, the glass is taken out to obtain glass with low hydroxyl content and high optical uniformity.

[0006] The present invention adopts a two-step melting method to prepare phosphate glass. The first step is high-temperature melting and stirring to make the glass components uniform; the second step is low-temperature melting in a tube and water is removed by introducing atmosphere; at the same time, the glass liquid is freely formed in the crucible to eliminate glass casting stripes; and the thermal stress is eliminated by precise annealing in a tubular furnace to obtain a phosphate glass with low hydroxyl content and high optical uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a process flow chart of the present invention;

[0008] Figure 2 The phosphate glass obtained by the process of the present invention and its effect under blue light irradiation;

[0009] Figure 3 The phosphoric acid glass prepared by this process has a -1 Absorption spectrum in the range;

[0010] Figure 4 The visible and near-infrared transmission spectra of the phosphate glass prepared by the process of the present invention are shown in FIG. Specific implementation cases:

[0011] The present invention is further described below in conjunction with the embodiments, but this should not limit the protection scope of the present invention.

[0012] A method for removing water in producing phosphate laser glass comprises the following steps: (1) According to the designed glass composition P2O5-Al2O3-K2O-Na2O-Sb2O3-Nb2O5-Er2O3-Yb2O3, the raw materials are high-purity aluminum metaphosphate, sodium metaphosphate, potassium metaphosphate, diammonium phosphate, antimony oxide, niobium oxide, erbium oxide and ytterbium oxide. Weigh each raw material according to the raw material composition. In this case, the total amount of glass oxide raw materials is 300 grams; (2) mixing the weighed raw materials evenly and then ball milling them until the particle size of the raw materials is less than 1 micron; (3) The milled raw materials are pre-fired at a temperature of 120°C for 2 hours, 600°C for 2 hours, and 800°C for 2 hours. (4) melting the pre-burned raw materials at a temperature of 1300°C for 3 hours, stirring with a stirring bar for 3 hours at a speed of 30 r / min; (5) After melting, the temperature of the molten glass is lowered to a suitable temperature for casting and molding. In this case, the temperature of the molten glass is 1000 degrees; (6) crushing the melted glass to obtain glass fragments, the size of which is about 1 mm; (7) Put the glass pieces into a graphite crucible, put it into a tube furnace, evacuate it, introduce nitrogen, and then heat the tube furnace at a rate of 1 degree / minute; heat it to 900 degrees and keep it warm for 8 hours, then turn off the tube furnace and let it cool with the furnace, and pass nitrogen protection throughout the process, and finally obtain a phosphate glass with low hydroxyl content and high optical uniformity.

Claims

1. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity, characterized in that: The raw materials are mixed evenly by ball milling, and the particle size is about 1 micron; the raw materials are pre-fired to reduce the volatilization of components; after pre-fired, the raw materials are melted at high temperature and stirred to obtain uniform bubble-free glass; the primary molten glass is crushed to obtain glass fragments with a size of 1-3mm; the glass fragments are melted in the atmosphere of a secondary low-temperature tube to remove water; the glass is freely formed in the crucible to reduce casting stripes; the glass is cooled with the furnace to eliminate the thermal stress of the glass.

2. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity as claimed in claim 1, characterized in that: The ball milling process can reduce the particle size of the raw material to between 500 nanometers and 1.5 micrometers after ball milling.

3. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity as claimed in claim 1, characterized in that: The pre-firing temperature system is kept at 120-200 degrees for 1-3 hours; and kept at 500-700 degrees for 1-3 hours.

4. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity as claimed in claim 1, characterized in that: The primary melting temperature is in the range of 1200-1350 degrees, and the melting time is in 1-3 hours.

5. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity as claimed in claim 1, characterized in that: The secondary tube is melted to remove water, and the melting temperature is in the range of 800-1000 degrees.

6. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity as claimed in claim 1, characterized in that: The secondary tube is melted and dehydrated, and the gases introduced are nitrogen, oxygen and argon.

7. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity as claimed in claim 1, characterized in that: The secondary tube is melted and dehydrated, and the crucible is made of a material that is not wettable with glass, such as graphite and amorphous carbon.

8. A process for preparing phosphate glass with low hydroxyl content and high optical uniformity as claimed in claim 1, characterized in that: The secondary melting and forming is carried out in the tube, and the secondary melting and heat preservation are directly cooled in the crucible without pouring and rapid cooling.

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