Heat treatment decolorization method and device for optical glass

Abstract

The invention relates to a heat treatment decoloration method and device for optical glass. Belongs to the technical field of optical glass production. The titanium-containing phosphate optical glass mainly solves the problem of poor light transmission of titanium-containing phosphate optical glass. The device is mainly characterized by comprising a box-type annealing furnace and a loading tool, wherein the annealing furnace is provided with a ventilation device and a gas outlet device; the loading tool is of a layered structure, and vent holes are formed in each layer of bearing plate. The method comprises the following steps: (1) placing glass to be decolorized in a closed annealing furnace through a loading tool, and heating to an annealing temperature; (2) carrying out heat preservation treatment on the glass heated to the annealing temperature, and simultaneously conveying oxygen into the furnace; (3) carrying out cooling treatment on the glass subjected to heat preservation treatment, and meanwhile, conveying oxygen into the furnace; and (4) the cooled glass is titanium-containing salt glass existing in the form of Ti < 4 + >. The light transmittance is 70% under the short wavelength of 440 nm or less, the light transmittance is 5% under the short wavelength of 390 nm or less, and the visible light transmittance is 99% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of optical glass production, and specifically relates to a heat treatment decolorization method and device for optical glass. Background Art

[0002] A titanium-containing phosphate optical glass is dark brown or nearly black after melting, forming and rapid annealing. It is opaque and has poor light transmittance, which affects the internal quality inspection, physical and chemical performance testing and subsequent optical imaging of the glass. This type of high-refractive-index and high-dispersion phosphate optical glass contains the Ti element. The Ti element is present in the glass as Ti 3+ or Ti 4+ It exists in the form of ions, and its form or valence is affected by the composition of the base glass, the melting atmosphere of the glass, the melting temperature and the cooling rate. In the silicate glass structure, Ti is generally present in the form of Ti 4+ The state exists, colorless, but due to Ti 4+ The ions strongly absorb ultraviolet rays, and the absorption band enters the purple-blue part of the visible light region, making the glass appear brownish yellow. Therefore, the titanium-containing silicate glass we see is generally brownish yellow, and its light transmission performance meets the requirements and does not affect the inspection of the internal quality of the glass and its subsequent use. However, in titanium-containing phosphate glass, oxygen vacancies are formed in the glass during the rapid cooling process of melting and forming, and part of the Ti in the glass structure is Ti 3+ exists in the form of, and Ti 3+ It forms a color center complex with metaphosphate, so the glass obtained after melting and cooling is dark brown or nearly black. After conventional heat treatment, the glass obtained is still dark brown glass, and its light transmittance is not improved. Summary of the invention

[0003] The present invention aims at solving the above problems and provides a method and device for heat-treating and decolorizing titanium-containing salt optical glass with extremely poor light transmittance obtained after melting, forming and rapid cooling.

[0004] The technical solution of the method of the present invention is: a heat treatment decolorization method for optical glass having oxygen vacancies and Ti 3+ The heat treatment decolorization of titanium-containing salt glass in the form of a titanium salt is characterized by comprising the following steps: (1) heating the glass to be decolorized to an annealing temperature in a closed annealing furnace through a loading device; (2) subjecting the glass heated to the annealing temperature to a heat preservation treatment while supplying oxygen into the furnace; (3) cooling the glass subjected to the heat preservation treatment while supplying oxygen into the furnace; (4) After the cooling treatment, the glass is Ti 4+Titanium-containing salt glass in the form of.

[0005] The technical solution of the method of the present invention is to use a Ti 3+ The heat treatment decolorization of titanium-containing phosphate glass in the form of a titanium-containing phosphate glass is characterized by comprising the following steps: (1) heating the glass to be decolorized after melting, forming and rapid cooling to an annealing temperature in a closed annealing furnace through a loading device; (2) The glass heated to the annealing temperature is subjected to a heat preservation treatment while oxygen is supplied into the furnace; the heat preservation temperature is Tg±30°C, the heat preservation time is 30 hours±20 hours, and Tg is the conventional annealing temperature of the glass to be decolorized; (3) Cooling the glass treated with heat preservation while supplying oxygen into the furnace; the cooling rate is 0.5°C / H to 10.0°C / H; (4) After the cooling treatment, the glass is Ti 4+ Titanium-containing phosphate glass in the form of.

[0006] In the technical solution of the method of the present invention, in step (2), steps (1) and (2), steps (2) and (3), or steps (1) to (3), the loading tool rotates relative to the oxygen inlet.

[0007] In the technical solution of the method of the present invention, the rotation speed of the loading tool relative to the oxygen inlet is 0-60 rpm; the oxygen concentration control range of the oxygen transported in the furnace is 21%-100% of 1 standard atmospheric pressure.

[0008] The loading tooling described in the technical solution of the method of the present invention is a layered structure, and the height of the glass to be decolorized loaded on each layer of the tooling does not exceed 2 / 3 of the height of the space of each layer of the tooling; and ventilation holes are provided on the loading tooling support plate.

[0009] The present invention heat treats optical glass with extremely poor light transmittance obtained after melting, forming and rapid cooling. First, a closed annealing furnace is selected, the internal heating elements and loading tooling of which are made of anti-oxidation materials, the tooling for loading glass in the furnace is fixed on a rotating table at the bottom of the heat treatment annealing furnace, and the tooling is a circular layered structure bracket, and the furnace is provided with an air inlet, an air outlet and an oxygen delivery control system; a suitable heat treatment process is formulated, including a heat preservation temperature Tg±30℃, a heat preservation time of 30 hours±20 hours, an effective cooling rate of 0.5℃ / H~10.0℃ / H, and a certain amount of oxygen is introduced into the furnace during the entire heat preservation and cooling stage, and the oxygen diffuses into the glass structure at high temperature, and is combined with oxygen vacancies in the glass structure to reduce its oxygen vacancy concentration, so that the originally unstable Ti in the glass 3+ Ions converted to Ti4＋ ions, dissolve Ti 3+ The color center complex formed with metaphosphate makes the original dark brown or black color of the glass lighter after heat treatment, and has good light transmittance, ensuring subsequent quality inspection, physical and chemical performance testing and use in optical imaging systems.

[0010] The technical solution of the device of the present invention is: a device specially used for a heat treatment decolorization method of optical glass, including a box-type annealing furnace and a loading tool, characterized in that: the annealing furnace is a closed heat treatment annealing furnace, and is provided with a ventilation device and an exhaust device; the loading tool is a layered structure, and ventilation holes are provided on the supporting plate of each layer.

[0011] In the technical solution of the device of the present invention, the annealing furnace is provided with a rotating device, and the loading tool is fixed on the rotating device.

[0012] In the technical solution of the device of the present invention, the annealing furnace is provided with a heating element and a muffle cover; the ventilation device is arranged at the lower part of the annealing furnace, and the gas outlet device is arranged at the upper part of the annealing furnace opposite to the ventilation device.

[0013] The heating element in the technical solution of the device of the present invention is a silicon-molybdenum rod, which is evenly distributed between the six surfaces of the inner wall of the furnace body and the outer wall of the internal muffle cover; the material of the loading tooling is a quartz plate, and the vent holes with an aperture of Φ5~Φ30mm are evenly distributed on the quartz plate.

[0014] The ventilation device in the technical solution of the device of the present invention includes an oxygen inlet hole, a pressure flow meter installed at the inlet hole, and an electric-controlled opening and closing valve of the inlet hole; the outlet device includes an outlet hole, an oxygen concentration monitor installed at the outlet hole, and an electric-controlled opening and closing valve of the outlet hole; the electric-controlled opening and closing valve of the inlet hole and the electric-controlled opening and closing valve of the outlet hole are automatically controlled by the monitored oxygen concentration value to deliver the set oxygen flow value.

[0015] The present invention places the glass to be decolorized in a closed annealing furnace for heating, and then heats up to a certain temperature and cools down. During the heat preservation and cooling stages, oxygen is transported into the furnace. At high temperatures, the oxygen diffuses into the glass structure and combines with oxygen vacancies in the glass structure, thereby causing Ti in the glass to decolorize. 3+ Convert to Ti 4＋ , disband Ti 3+ With O 2- The color center complex formed makes the glass lighter in color. The heat treatment device used in this method adopts a closed annealing furnace, the internal heating elements and loading tools of which are made of anti-oxidation materials. The tooling for loading glass in the furnace is fixed on the rotating table at the bottom of the heat treatment annealing furnace and the tooling is a circular layered structure bracket; the furnace is provided with air inlet, air outlet and oxygen delivery control system.

[0016] The beneficial effects of the present invention are as follows: by effectively decolorizing the titanium-containing phosphate optical glass with extremely poor light transmittance obtained after melting, forming and rapid cooling, a light transmittance of 80% at a wavelength of 440 nm or less, a light transmittance of 5% at a wavelength of 380 nm or less, and a visible light transmittance of more than 99% are obtained, thereby improving the physical and chemical performance detection, product quality inspection and optical imaging capabilities of the later optical glass.

[0017] Good light transmittance ensures subsequent quality inspection, physical and chemical performance testing and use in optical imaging systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic diagram of the structure of an optical glass decolorizing annealing furnace.

[0019] In the figure: 1-furnace insulation layer; 2-heating element; 3-muffle cover in the furnace; 4-loading tooling; 5-ventilation device; 6-gas outlet device; 7-rotating device. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0021] like Figure 1 As shown, an embodiment of the device of the heat treatment decolorization method of optical glass of the present invention comprises a box-type annealing furnace and a loading tool 4. Among them, the annealing furnace is a closed heat treatment annealing furnace, comprising a furnace body 1, a ventilation device 5, an exhaust device 6, a rotating device 7, a heating element 2 and a muffle cover 3. The heating element 2 is a silicon molybdenum rod, and is evenly distributed between the six surfaces of the inner wall of the furnace body 1 and the outer wall of the internal muffle cover 3. The ventilation device 5 is arranged at the lower part of the annealing furnace, including an oxygen inlet hole, a pressure flow meter installed at the inlet hole, and an electric control opening and closing valve of the inlet hole. The exhaust device 6 is arranged at the upper part of the annealing furnace opposite to the ventilation device 5, including an outlet hole, an oxygen concentration monitor installed at the outlet hole, and an electric control opening and closing valve of the outlet hole. The oxygen intake is controlled by a linkage system composed of an inlet hole and an outlet hole. The system automatically controls the inlet hole and the outlet hole valve switch and the flow value of oxygen delivered at the inlet hole through the monitored oxygen concentration value. The rotating device 7 is a rotating table, which is arranged at the bottom center of the furnace body 1. The loading fixture 4 is a layered structure, which is fixed on the rotating table. The loading fixture 4 is made of a quartz plate, and each layer of the quartz plate is provided with evenly distributed vents, and the aperture of the vents is Φ5~Φ30mm, which is convenient for the rapid and even spread of heat and oxygen.

[0022] An embodiment of a heat treatment decolorization method of an optical glass according to the present invention is used for an optical glass having oxygen vacancies and having Ti 3+ Thermal treatment of titanium-containing phosphate glass in the form of decolorization comprises the following steps: (1) Place the glass to be decolorized after melting, forming and rapid cooling in a closed annealing furnace through a loading fixture 4, and evenly load it on each layer of the loading fixture 4. The height of the glass loaded on each layer of the loading fixture does not exceed 2 / 3 of the height of the space of each layer of the loading fixture, and heat it to the annealing temperature; the rotation speed of the loading fixture 4 is 20-30 rpm; (2) The glass heated to the annealing temperature is subjected to heat preservation treatment; the heat preservation temperature is Tg±30°C, the heat preservation time is 30 hours±20 hours, and Tg is the conventional annealing temperature of the glass to be achromatic; the rotation speed of the loading fixture 4 is 30 to 50 rpm, and oxygen is supplied to the furnace at the same time, and the oxygen concentration is controlled in the range of 60% to 90% of 1 standard atmospheric pressure; (3) Cooling the glass that has been heat-insulated; the cooling rate is 0.5°C / H to 10.0°C / H; the rotation speed of the loading fixture 4 is 30 to 50 rpm, and oxygen is supplied to the furnace at the same time, and the oxygen concentration is controlled in the range of 60% to 90% of 1 standard atmospheric pressure; (4) After the cooling treatment, the glass is Ti 4+ The titanium-containing phosphate glass in the form of amorphous titanium has a transmittance of 70% at a wavelength of 440nm or less, a transmittance of 5% at a wavelength of 390nm or less, and a visible light transmittance of more than 99%.

[0023] The concentration control range of the introduced oxygen is proportional to the degree of decolorization of the glass. The higher the oxygen concentration, the stronger the decolorization ability.

Claims

1. A heat treatment decolorization method for optical glass having oxygen vacancies and Ti 3+ Heat-treated decolorization of titanium-containing salt glass in the form of The following steps are involved: (1) placing the glass to be decolorized in a closed annealing furnace through a loading tool (4) and heating it to an annealing temperature; (2) subjecting the glass heated to the annealing temperature to a heat preservation treatment while supplying oxygen into the furnace; (3) cooling the glass subjected to the heat preservation treatment while supplying oxygen into the furnace; (4) After the cooling treatment, the glass is Ti 4+ Titanium-containing salt glass in the form of.

2. The method for heat treatment decolorization of optical glass according to claim 1, for optical glass having oxygen vacancies and containing Ti 3+ Heat-treated decolorized titanium-containing phosphate glass in the form of The following steps are involved: (1) placing the glass to be decolorized after melting, forming and rapid cooling in a closed annealing furnace through a loading tool (4) and heating it to an annealing temperature; (2) The glass heated to the annealing temperature is subjected to a heat preservation treatment while oxygen is supplied into the furnace; the heat preservation temperature is Tg±30°C, the heat preservation time is 30 hours±20 hours, and Tg is the conventional annealing temperature of the glass to be decolorized; (3) Cooling the glass treated with heat preservation while supplying oxygen into the furnace; the cooling rate is 0.5°C / H to 10.0°C / H; (4) After the cooling treatment, the glass is Ti 4+ Titanium-containing phosphate glass in the form of.

3. The method for heat treatment decolorization of optical glass according to claim 1 or 2, characterized in that: In the step (2), steps (1) and (2), steps (2) and (3), or steps (1) to (3), the loading tool (4) rotates relative to the oxygen inlet.

4. The method for heat treatment decolorization of optical glass according to claim 3, characterized in that: The rotation speed of the loading tool (4) relative to the oxygen inlet is 0 to 60 revolutions per minute; and the control range of the oxygen concentration of the oxygen transported in the furnace is 21% to 100% of 1 standard atmospheric pressure.

5. A method for heat treatment decolorization of optical glass according to claim 1, 2 or 4, characterized in that: The loading tool (4) is a layered structure, and the height of the glass to be decolorized loaded on each layer of the tool does not exceed 2 / 3 of the height of the space of each layer of the tool; and ventilation holes are provided on the bearing plate of the loading tool (4).

6. A device specially used for the heat treatment decolorization method of an optical glass as claimed in any one of claims 1 to 5, comprising a box-type annealing furnace and a loading tool (4), characterized in that: The annealing furnace is a closed heat treatment annealing furnace and is provided with a ventilation device (5) and an air outlet device (6); the loading tooling (4) is a layered structure, and ventilation holes are provided on the bearing plate of each layer.

7. The device for heat treatment and decolorization of optical glass according to claim 6, characterized in that: The annealing furnace is provided with a rotating device (7), and the loading tool (4) is fixed on the rotating device (7).

8. The device for heat treatment and decolorization of optical glass according to claim 7, characterized in that: The annealing furnace is provided with a heating element (2) and a muffle cover (3); the ventilation device (5) is arranged at the lower part of the annealing furnace, and the gas outlet device (6) is arranged at the upper part of the annealing furnace opposite to the ventilation device (5).

9. The device for heat treatment and decolorization of optical glass according to claim 8, characterized in that: The heating elements (2) are silicon-molybdenum rods and are evenly distributed between the six surfaces of the inner wall of the furnace body (1) and the outer wall of the internal muffle cover (3); the material of the loading tooling (4) is a quartz plate, and ventilation holes with an aperture of Φ5 to Φ30 mm are evenly distributed on the quartz plate.

10. A device for heat treatment and decolorization of optical glass according to any one of claims 6 to 9, characterized in that: The ventilation device (5) comprises an oxygen inlet hole, a pressure flow meter installed at the inlet hole, and an electric-controlled opening and closing valve of the inlet hole; the outlet device (6) comprises an outlet hole, an oxygen concentration monitor installed at the outlet hole, and an electric-controlled opening and closing valve of the outlet hole; the electric-controlled opening and closing valve of the inlet hole and the electric-controlled opening and closing valve of the outlet hole are automatically controlled to deliver a set oxygen flow value through the monitored oxygen concentration value.

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