CN103086379A - A radiation intercepting device for a crucible for electron beam melting - Google Patents

Abstract

The invention belongs to the technical field of metallurgical smelting, and particularly relates to a special radiation interception device for electron beam smelting. In the device, a radiation interception cover is positioned above a smelting crucible and movably arranged at the top of a furnace wall through a sliding suspension rod, the radiation interception cover is movably connected with the sliding suspension rod through a suspension hinge buckle, the radiation interception cover is spherical, the concave surface of the radiation interception cover faces downwards, the focus point of the concave surface is positioned at the center of the smelting crucible, and an arc-shaped notch is formed in the radiation interception cover. The radiation interception cover has the advantages of simple structure, practical function and convenience in manufacture, and can intercept the heat radiation of the silicon melt and the electron beam reflected by the surface of the silicon melt and act on the surface of the silicon melt again, so that the energy utilization rate of the electron beam is greatly improved, and the amplitude is improved by 20-50%.

Description

A radiation intercepting device for a crucible for electron beam melting

the

technical field

The invention belongs to the technical field of metallurgical smelting, in particular to a radiation intercepting device for electron beam smelting.

Background technique

At present, the preparation of polysilicon materials for solar cells has formed a large-scale production worldwide. The main preparation method is the improved Siemens method, but its comprehensive power consumption is as high as 170kW h/kg, and the production is intermittent, which cannot be formed in the production of Si. Continuous operation, and this method adopts backward thermal chemical vapor deposition in the core link of the process. There are too many links in the process flow, and the primary conversion rate is low, which leads to too long process time and increases material consumption and energy consumption costs.

For this reason, countries all over the world are actively exploring a new process for preparing high-purity silicon materials. Among them, the metallurgical method for preparing polysilicon is considered to be the most important technology due to its short production cycle, low pollution, low cost, relatively simple process, and controllable scale. One of the technologies that can most effectively reduce the production cost of polysilicon has become a hot spot in the research and development of countries all over the world. Electron beam melting technology is one of the important methods in the metallurgical preparation of solar-grade silicon. It uses electron beams with high energy density As a smelting heat source process, it can effectively reduce evaporative impurities such as phosphorus, aluminum, and calcium in polysilicon. Most of the crucibles used in the existing electron beam smelting process are water-cooled copper crucibles, mainly because they can be reused and avoid secondary Secondary pollution and other advantages.

Since the silicon material is in direct contact with the water-cooled copper crucible during the smelting process, its thermal conductivity is relatively good, resulting in more heat taken away by the water-cooling system. Previous crucible designers mainly started with reducing the heat taken away by the water-cooling system to increase the energy of the electron beam. The utilization rate, such as: increasing the crucible substrate and so on. Although this method can improve the energy utilization rate of the electron beam, it cannot increase the energy utilization rate of the electron beam without limit. If we want to continue to improve the energy utilization rate of the crucible, we need to start from other aspects.

Contents of the invention

In order to overcome the above disadvantages, the present invention provides a radiation intercepting device for a crucible for electron beam smelting. The device has a simple structure, adopts a radiation intercepting cover to intercept reflected thermal radiation and electron beam energy, and then reflects back into the melting crucible to continue acting on the melt, thereby improving the utilization efficiency of the electron beam energy.

The technical solution adopted by the present invention to achieve the above object is: a radiation intercepting device for a crucible for electron beam smelting, including a radiation intercepting cover, a sliding suspension rod and a vacuum smelting device. In the vacuum smelting device, the inside of the furnace wall is a melting chamber, Furnace door is installed on the furnace wall, the water-cooling tray is fixedly installed on the bottom of the furnace wall, the water inlet and outlet are opened on the water-cooling tray, the melting crucible is fixed on the water-cooling tray, the vacuum pump group is fixed on the furnace wall, and the electron gun is fixed Installed on the top of the furnace wall, it is characterized in that: the radiation intercepting cover is located above the melting crucible, and is movably installed on the top of the furnace wall through a sliding suspension rod, and the radiation intercepting cover and the sliding suspension rod are movably connected by a suspension hinge buckle.

The radiation intercepting shield is in the shape of a spherical surface, with its concave surface facing downwards, the focal point of the concave surface is located at the center of the melting crucible, and an arc-shaped gap is opened on it.

The radiation intercepting shield is located 10-30 cm above the melting crucible, and its orthographic projection is a circle with a radius of 15-40 cm.

The radiation intercepting shield is made of quartz, 304 stainless steel, graphite or copper.

There are 3-5 sliding suspension rods, and each sliding suspension rod is equipped with an independent driving device.

The radius of the arc-shaped notch is 5-10cm.

The device of the present invention is simple in structure and practical in function, and the device has the following advantages:

1. The radiation intercepting cover can intercept the thermal radiation of the silicon melt. By intercepting the radiation of the silicon liquid surface, the radiation is reflected and re-acted on the silicon liquid surface, which effectively reduces the energy lost due to thermal radiation and improves the electron beam. Energy utilization of the equipment.

2. The radiation intercepting shield can not only intercept the radiation generated by the silicon melt, but also intercept the energy reflected by the electron beam. Previous studies have shown that the energy utilization rate of the electron beam is only about 75%. The main reason is that the electron beam bombards the silicon melt. 25% of the energy is reflected at the surface of the body fluid, and the radiation intercepting shield can intercept the reflected energy for melting silicon melt.

In summary, the present invention provides a radiation intercepting device for a crucible for electron beam smelting, which has the advantage of being easy to manufacture. The radiation intercepting device can intercept the thermal radiation of the silicon melt and the electron beam reflected by the surface of the silicon melt. , re-acting on the surface of the silicon melt, greatly improving the energy utilization rate of the electron beam by 20-50%.

Description of drawings

Fig. 1 is a schematic structural diagram of a radiation intercepting device for a crucible for electron beam melting.

Fig. 2 is a top view structure diagram of the radiation intercepting cover in Fig. 1

In the figure: 1. Vacuum pump group, 2. Sliding suspension rod, 3. Electron gun, 4. Furnace wall, 5. Electron beam, 6. Radiation intercepting cover, 7. Furnace door, 8. Melting chamber, 9. Melting crucible, 10 .Molten liquid, 11. Water inlet, 12. Water outlet, 13. Water cooling tray, 14. Hanging hinge buckle, 15. Notch

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments and drawings, but the present invention is not limited to specific embodiments.

Example 1

As shown in Figure 1 and Figure 2, a radiation intercepting device for a crucible for electron beam melting includes a radiation intercepting cover, a sliding suspension rod and a vacuum melting device. In the vacuum melting device, the inside of the furnace wall 4 is a melting chamber 8, and the furnace Furnace door 7 is installed on the wall, water-cooling tray 13 is fixedly installed on the bottom of furnace wall 4, water inlet 11 and water outlet 12 are opened on the water-cooling tray, melting crucible 9 is fixedly installed on the water-cooling tray, vacuum pump group 1 is fixedly installed on the furnace On the wall, the electron gun 3 is fixedly installed on the top of the furnace wall, the radiation intercepting cover 6 is located above the melting crucible, and is movably installed on the top of the furnace wall through the sliding suspension rod 2, and the radiation intercepting cover 6 and the sliding suspension rod 2 are hinged by suspension Buckle activity connection.

The radiation intercepting shield is in the shape of a sphere, with its concave facing downwards. The focal point of the concave surface is located at the center of the melting crucible. The radiation intercepting shield is located 30cm above the melting crucible. Its orthographic projection is circular with a radius of 15cm. The radiation intercepting shield is made of copper.

There is also an arc-shaped notch 15 at the direct radiation position of the electron beam on the radiation intercepting cover, and the radius of the arc-shaped notch is 5 cm.

The arc-shaped notch is mainly used to avoid the direct radiation of the electron beam, so that the radiation of the electron beam directly acts on the melt of the melting crucible.

There are 3 sliding suspension rods, and each sliding suspension rod is equipped with an independent driving device. During the smelting process, the tilt angle of the radiation interception cover can be adjusted by adjusting the lifting of the sliding suspension rod, so that the electron beam and energy reflected by the radiation interception cover Acts on the central position of the melting crucible.

The comparison experiment of electron beam smelting and purification of polysilicon using the above smelting equipment and traditional smelting equipment:

(a) The traditional smelting device melts 0.5kg of silicon material, and fixes the electron beam power at 12kw to ensure that the silicon material in the electron beam crucible cannot be completely melted. When a stable molten pool is formed, the beam is turned off immediately. Take out the silicon ingot and cut it in the center, corrode, analyze the cross-sectional morphology, mark the shape of the molten pool, calculate the area of the molten pool at the cross-section, and record it as A0;

b). According to the same smelting parameters, use a device with a radiation intercepting cover for smelting, calculate the molten pool area at the section, and record it as A1;

c). By comparing the molten pool area A1 and A0 of the silicon ingot section, it is found that A1->A0, which proves that the water-cooled copper crucible with radiation interception can greatly improve the energy utilization rate of the electron beam, and the energy utilization rate of the electron beam can be increased by 20 %.

Example 2

As shown in Figures 1 and 2, a radiation intercepting device for a crucible for electron beam smelting, the device is the same as the device in Example 1 except that the following components are different:

The radiation intercepting shield is located 10cm above the melting crucible, and its orthographic projection is a circle with a radius of 40cm. The radiation intercepting shield is made of graphite.

There is also an arc-shaped gap 15 at the direct radiation position of the electron beam on the radiation intercepting cover, the radius of the arc-shaped gap is 10cm, and there are 5 sliding suspension rods.

After performing the comparative experiment as in Example 1, the energy utilization rate of the electron beam was increased by 50%.

Example 3

As shown in Figures 1 and 2, a radiation intercepting device for a crucible for electron beam smelting, the device is the same as the device in Example 1 except that the following components are different:

The radiation intercepting shield is located 18cm above the melting crucible, and its orthographic projection is a circle with a radius of 30cm. The radiation intercepting shield is made of quartz.

There is also an arc-shaped gap 15 at the direct radiation position of the electron beam on the radiation intercepting cover, the radius of the arc-shaped gap is 8cm, and there are 4 sliding suspension rods.

After performing the comparative experiment as in Example 1, the energy utilization rate of the electron beam was increased by 42%.

Example 4

As shown in Figures 1 and 2, a radiation intercepting device for a crucible for electron beam smelting, the device is the same as the device in Example 1 except that the following components are different:

The radiation intercepting shield is located 22cm above the melting crucible, and its orthographic projection is a circle with a radius of 25cm. The radiation intercepting shield is made of graphite.

There is also an arc-shaped gap 15 at the direct radiation position of the electron beam on the radiation intercepting cover, the radius of the arc-shaped gap is 6cm, and there are 4 sliding suspension rods.

After performing the comparative experiment as in Example 1, the energy utilization rate of the electron beam was increased by 32%.

Claims (6)

1. an electron beam melting is with the radiation blocking apparatus of crucible, comprise radiation interception cover, slip hanger bar and vacuum melting device, in the vacuum melting device, inside, furnace wall (4) is working chamber (8), fire door (7) is installed on the furnace wall, water-cooled pallet (13) is fixedly installed in bottom, furnace wall (4), have water-in (11) and water outlet (12) on the water-cooled pallet, smelting pot (9) is fixedly installed on the water-cooled pallet, vacuum pump group (1) is fixedly installed on the furnace wall, electron beam gun (3) is fixedly installed in the top, furnace wall, it is characterized in that: radiation interception cover (6) is positioned at above smelting pot, and be movably installed in the top of furnace wall by slip hanger bar (2), be flexibly connected by hanging kinge-joint knot between radiation interception cover (6) and slip hanger bar (2).

2. a kind of electron beam melting according to claim 1 is with the radiation blocking apparatus of crucible, it is characterized in that: described radiation interception cover is spherical shape, its concave surface down, the concave surface focus point is positioned at the smelting pot center, also has a circular arc cutaway (15) on it.

3. arbitrary described a kind of electron beam melting is with the radiation blocking apparatus of crucible according to claim 1 and 2, and it is characterized in that: described radiation interception cover is positioned at smelting pot top 10-30cm, and its orthographicprojection be circle, and radius is 15-40cm.

4. arbitrary described a kind of electron beam melting is with the radiation blocking apparatus of crucible according to claim 1 and 2, and it is characterized in that: described radiation interception cover material is quartz, 304 stainless steels, graphite or copper.

5. a kind of electron beam melting according to claim 1 is with the radiation blocking apparatus of crucible, and it is characterized in that: described slip hanger bar is the 3-5 root, and every slip hanger bar is equipped with independently drive unit.

6. a kind of electron beam melting according to claim 2 is with the radiation blocking apparatus of crucible, and it is characterized in that: the radius of described circular arc cutaway is 5-10cm.

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