CN113684535A - Large-size sapphire plate growth device and method by die-guided growth method - Google Patents

Abstract

The invention discloses a large-size sapphire plate die-guide growth device and a large-size sapphire plate die-guide growth method, wherein the device comprises a furnace body, two sides of the furnace body are in a split door structure, a plate-shaped graphite resistance heater is adopted, a graphite hard felt is used as a heat insulation material, an integral thermal field is in a dual-temperature-zone structure, four plate-shaped graphite heaters are arranged on the periphery of a circular crucible and serve as a main heating zone, and the device comprises the following steps: step 1: firstly, charging the furnace, and then vacuumizing the furnace body; step 2: then, inflating the furnace body, and then heating the furnace body to melt the sapphire; and step 3: seeding and shouldering to an equal diameter stage and continuing until the crystal growth is finished; and 4, step 4: then carrying out in-situ annealing on the furnace body, cooling to room temperature, and taking out the crystal. The design of the double-temperature zone avoids the defects of dislocation, cracking and the like caused by overlarge stress of the crystal, avoids the generation of bubbles in the crystal due to the temperature fluctuation of the melt at high temperature, and ensures the high quality of the crystal.

Description

Large-size sapphire plate growth device and method by die-guided growth method

Technical Field

The invention relates to the technical field of crystal material preparation, in particular to a large-size sapphire plate growth device and a growth method by a die-guiding method.

Background

With the rapid development of the photoelectric/infrared system for military and civil use, people have urgent needs for large-area photoelectric window materials (the length and the width are more than or equal to 250mm), and meanwhile, the requirements for high hardness, high strength, wide waveband and high transmittance are more and more strong on the performance of the window materials. For example, infrared transmittance indices and abrasion resistance are important indices for photovoltaic windows, infrared sash windows, ranging and tracking instrument windows for aircraft, ships and ground vehicles.

The sapphire single crystal is used as an excellent wide-waveband light-transmitting material, has good wave-transmitting rate in ultraviolet, visible light, infrared waveband and microwave, and can meet the requirement of multi-mode composite guidance; meanwhile, the sapphire single crystal has excellent mechanical property, chemical stability and high temperature resistance, high strength and high hardness, and can work in a severe environment of nearly 2000 ℃, so the sapphire single crystal is the best photoelectric window material. Although large-sized sapphire crystals have numerous applications in various fields of military use and civil use, the export of related technologies and materials is prohibited in western countries such as the united states, so that large-sized high-quality sapphire crystals cannot be sufficiently supplied internationally.

The most common shape of window material is flat. Currently, the main production methods of large-size sapphire single crystals include a heat exchange method, a kyropoulos method, a horizontally oriented zone melting method, a mold guiding method and the like. Due to the technical difference, the mold guiding method (also called EFG method) and the horizontal orientation zone melting method are most suitable for the production of large-size sapphire single crystal plates. Both have the advantage that large-size single crystals in the form of plates can be produced directly. The produced crystal blank is a plate with the size close to the target size, and no additional processing is needed except grinding and polishing. The horizontal directional zone-melting method has been able to grow sapphire panels with maximum size of 457mm x 914mm x 38mm, manufactured by Rubicon Technology, inc, of american company, which is still in the laboratory stage due to excessive stress and low mechanical strength of the grown crystals, limiting the range of application, whereas the large size sapphire plates grown by the guided mode method have been industrially produced in saint gobain, france. Another main advantage of growing the sapphire large plate by the guided mode method is that the crystal growth speed of the sapphire large plate grown by the guided mode method is high and reaches up to 25mm/h, the whole crystal growth period only needs 3 days, the crystal growth speeds of other growing methods are all below 5mm/h, and the whole crystal growth period is about 2 weeks.

However, the technology of large-size (more than or equal to 250mm) high-quality sapphire plate growth by a mold-guiding method is still blank at present; and other crystal growth methods cannot process large-size (more than or equal to 250mm) sapphire plates in size or quality. Even if occasionally obtaining high quality crystals allows large sapphire plates to be processed, it is expensive and cannot meet the requirements of mass production. For example, the most common method for producing large-size sapphire crystals in the industry is the kyropoulos method or the heat exchange method, the product is an approximately cylindrical sapphire ingot, and a sapphire single crystal plate is required to be produced by means of cutting processing. And the crystal growth and processing cycle of the mode is long, the waste of crystal raw materials is serious, and meanwhile, when the cutting is carried out, a plate-shaped area which has no bubble layer and meets the requirements of strength and wave transmittance is difficult to find in the cylindrical crystal interval.

Disclosure of Invention

1. Technical problem to be solved

The invention aims to solve the problems in the prior art and provides a growth device and a growth method for a large-size sapphire plate by a die-casting method.

2. Technical scheme

In order to achieve the purpose, the invention adopts the following technical scheme:

the utility model provides a jumbo size sapphire board die-guiding method growth device, includes the furnace body, the furnace body both sides are to the structure of opening the door mutually, adopt plate graphite resistance heater, and the hard felt of graphite is as insulation material, and whole thermal field is two warm area structures, and circular crucible has four slice plate form graphite heaters all around, for the main zone of heating, is equipped with the afterheater in the parallel both sides of sapphire board large face, and main heating separates both with the afterheating warm area as the heat screen by the hard felt of graphite, and the heat screen level is placed in crucible cover upper portion and is located the mould both sides.

Preferably, the main heating zone and the rear heating zone are independently controllable.

Preferably, the die is a splicing structure of two plane plates, the width of the die is 250-450mm, the thickness of the die is 8-30mm, the height of the die is 40-150mm, the width of the middle capillary seam is 0.2-2mm, and the top of the die is at an included angle of 90-180 degrees.

Preferably, the large surface of the sapphire plate is an A surface, the pulling direction is an M direction or a C direction, and the length of the sapphire plate is 400-1000 mm.

Preferably, the crucible material is molybdenum, tungsten, iridium or rhenium.

Preferably, the material of the mould is molybdenum, tungsten, iridium or rhenium.

Preferably, the furnace body is a cuboid.

Preferably, the crucible is fixedly connected with the inner bottom of the furnace body through a crucible supporting rod.

The invention also provides a growth method of the large-size sapphire plate by the die-casting method, which comprises the following steps:

step 1: firstly, charging raw materials, and then vacuumizing the furnace body;

step 2: then, inflating the furnace body, and then heating the furnace body to melt the sapphire;

and step 3: seeding and shouldering to an equal diameter stage and continuing until the crystal growth is finished;

and 4, step 4: then carrying out in-situ annealing on the furnace body, lowering the crucible, cooling to room temperature, and taking out the crystal.

3. Advantageous effects

Compared with the prior art, the invention has the advantages that:

(1) according to the invention, the dual-temperature zone design avoids the defects of dislocation, cracking and the like caused by overlarge crystal stress, avoids the generation of bubbles in the crystal due to the fluctuation of the melt temperature at high temperature, and ensures the high quality of the crystal.

(2) According to the invention, a high-quality sapphire plate with the maximum width of 450mm can be grown, and the domestic urgent requirements on large-size photoelectric windows and transparent armors are met.

Drawings

FIG. 1 is a boiling point diagram of a large-size sapphire plate growth method by a mold-guide method according to the invention;

fig. 2 is a schematic structural diagram of a large-size sapphire plate growth apparatus by a mold-guide method according to the present invention.

In the figure: 1-plate-shaped graphite heaters; 2-graphite hard felt; 3-covering the crucible; 4-a crucible; 5 sapphire plate; 6-molding; 7-graphite hard felt; 8-crucible support rods; 9-furnace body.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Example 1:

referring to fig. 2, the large-size sapphire plate die-guided growth device comprises a furnace body 9, wherein the furnace body 9 is a cuboid, two sides of the furnace body 9 are of a door structure which is oppositely opened, a plate-shaped graphite resistance heater 1 and a graphite hard felt 2 are adopted as heat insulation materials, and an integral thermal field is of a dual-temperature-zone structure;

in the invention, four plate-shaped graphite heaters 1 are arranged around a circular crucible 4, the crucible 4 is fixedly connected with the inner bottom of a furnace body 9 through a crucible supporting rod 8, and the crucible 4 is made of molybdenum, tungsten, iridium or rhenium and is a main heating zone;

in the invention, the main heating zone and the rear heating zone can be respectively and independently controlled, the rear heaters are arranged on two sides parallel to the large surface of the sapphire plate 5, the large surface of the sapphire plate 5 is an A surface, the pulling direction is M direction or C direction, and the length of the sapphire plate is 400-1000 mm;

in the invention, a main heating temperature zone and a post heating temperature zone are separated by taking a graphite hard felt 2 as a heat shield, the heat shield is horizontally placed at the upper part of a crucible cover 3 and positioned at two sides of a mould 6, and the mould 6 is in a splicing structure of two plane plates;

in the invention, the width of the die 6 is 250-450mm, the thickness is 8-30mm, the height is 40-150mm, the width of the middle capillary seam is 0.2-2mm, the top of the die 6 forms an included angle of 90-180 degrees, and the die 6 is made of tungsten, molybdenum, tantalum or iridium.

The invention discloses a large-size sapphire plate die-guide growth method, which comprises the following steps:

step 1: firstly, charging raw materials, and then vacuumizing the furnace body 9;

step 2: then, the furnace body 9 is inflated, and then the temperature of the furnace body 9 is raised to melt the sapphire;

and step 3: seeding and shouldering to an equal diameter stage and continuing until the crystal growth is finished;

and 4, step 4: then, the furnace body 9 is annealed in situ, cooled to room temperature, and then the crystal is taken out.

According to the invention, the dual-temperature zone design avoids the defects of dislocation, cracking and the like caused by overlarge crystal stress, avoids the generation of bubbles in the crystal due to the fluctuation of the melt temperature at high temperature, and ensures the high quality of the crystal.

In the present invention, any liquid and gas directly contacting with the upper part of the liquid will eventually reach a gas phase equilibrium state, and the alumina melt will reach a dynamic equilibrium with the gas phase on the upper part of the alumina melt after a certain time, and if there is a disturbance between the two phases, such as temperature fluctuation or mechanical vibration, bubbles generated by the melt may rise to the growth interface through the capillary gap of the mold and enter the inside of the crystal.

In the present invention, FIG. 1 is a general bubble point diagram, where component 1, which boils at a higher temperature, may be a sapphire melt, and component 2, which boils at a lower temperature, may be any gas phase component (argon, CO or CO2) dissolved in the sapphire melt. As shown in fig. 1, the solubility of component 2 in component 1 decreases with increasing temperature.

In the present invention, a melt in vapor phase equilibrium at a specific temperature is supersaturated with dissolved gas at a higher temperature. Therefore, the increase in temperature promotes the formation of bubbles in the melt. In order to inhibit the formation of bubbles in a melt, the temperature of a rear heater is only regulated in the crystal growth process, the temperature of the melt in a crucible is kept constant, and the generation of bubbles in the crystal due to the fact that the bubbles in the melt enter the crystal is avoided from the source.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (9)

1. The utility model provides a jumbo size sapphire board die-guiding method growth device, includes furnace body (9), its characterized in that, furnace body (9) both sides are the structure of opening a door mutually, adopt platelike graphite resistance heater (1), and hard felt of graphite (2) are as insulation material, and whole thermal field is two warm area structures, and circular crucible (4) have four platelike graphite heater (1) all around, for the main zone of heating, are equipped with the after-heating ware in sapphire board (5) big parallel both sides of face, and main heating and after-heating warm area are separated both as the heat screen by hard felt of graphite (2), and the heat screen level is placed in crucible cover (3) upper portion and is located mould (6) both sides.

2. The large-size sapphire plate die-guided growth device of claim 1, wherein the main heating zone and the post heating zone are independently controllable.

3. The large-size sapphire plate die-guide growth device according to claim 1, wherein the die (6) is a split structure of two flat plates, the width of the die (6) is 250-450mm, the thickness is 8-30mm, the height is 40-150mm, the width of the middle capillary seam is 0.2-2mm, and the top of the die (6) is at an included angle of 90-180 degrees.

4. The large-size sapphire plate die-guided growth device according to claim 1, wherein the large surface of the sapphire plate (5) is an A surface, the pulling direction is M direction or C direction, and the length of the sapphire plate is 400-1000 mm.

5. The large-size sapphire plate die-casting growth device according to claim 1, wherein the crucible (4) is made of molybdenum, tungsten, iridium or rhenium.

6. The large-size sapphire plate die-casting growth device according to claim 1, wherein the die (6) is made of molybdenum, tungsten, iridium or rhenium.

7. The large-size sapphire plate die-guide growth device according to claim 1, wherein the furnace body (9) is a cuboid.

8. The large-size sapphire plate die-guide growth device according to claim 1, wherein the crucible (4) is fixedly connected with the inner bottom of the furnace body (9) through a crucible supporting rod (8).

9. A large-size sapphire plate growth method by a die-guiding method is characterized by comprising the following steps:

step 1: firstly, charging raw materials, and then vacuumizing the furnace body (9);

step 2: then, the furnace body (9) is inflated, and then the temperature of the furnace body (9) is raised to melt the sapphire;

and step 3: seeding and shouldering to an equal diameter stage and continuing until the crystal growth is finished;

and 4, step 4: then, the furnace body (9) is annealed in situ, cooled to room temperature, and then the crystal is taken out.

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