RU1382052C - Device for growing profiled crystals - Google Patents

Abstract

The invention relates to the field of producing single crystals by melt extrusion using molds and allows to improve the quality of crystals by reducing the asymmetry of the thermal field. The device includes a crucible with a lid. A capillary beam of roVC is fixed in the lid. On its end, the main formers are installed symmetrically to the crucible axis. A filler former is placed along the crucible axis. Its outer contour follows the contours of the main formers by a value of 0.6-0.7 of their parameter in a horizontal section. When crystals are grown, a single-crystal reflective screen grows with them. The latter increases the temperature of the inner wall of the product, aligns the thermal field along the cross section of the crystal. The invention provides a reduction of residual stresses in the crystal by 1.5 times, reduces the dislocation density by 5 times. Difference is reduced by 3 times. 8 ill., 1 tab. S / s

Description

The invention relates to the field of producing single crystals by growing them from a melt film using die formers and can be used in enterprises growing profiled crystals, for example, enterprises of the Ministry of Chemical Industry, Ministry of Electro Industry, and the Ministry of Fertilizers.

The aim of the invention is to improve the quality of crystals by reducing the asymmetry of the thermal field.

Figure 1 shows a diagram of a device for group growing shaped crystals by the Stepanov method; figure 2 is a top view of figure And; on League „3, 5, 6, 7, 8, the constructions of additional formers are shown.

The device includes a crucible 1 with a lid 2 mounted on it, in which a bunch of capillaries 3 is fixed. On its end symmetrically to the thermal and geometric axis of the crucible 1, the main formers 4 are installed, along the axis of the crucible there is an additional former S, the height of the additional former 5 is less than the height of the main former by (0.01-0.03) the numerical value of the radial temperature gradient at the crystallization front. Clearance between the outer surface

about: OS K

with a to

the main shaper and an additional 5 is 2-5 mm.

The device operates as follows

Into crucible 1 through holes in the lid. raw materials are loaded; the device is placed in a crystal growth apparatus of known design. A controlled medium is created in the growth chamber and, increasing the temperature, the raw materials are melted. The melt rises to the molds through a bunch of capillaries, and then, through their capillary channels, into the crystallization zone

Then the seed crystal is fed to the former. The seed crystal can be of any shape, but each former must overlap at least at one point. The seed is brought into contact with the main highest former and molten to contact with an additional lower former. 5 ° The formed melt flows down through the capillaries into the crucible. Then, the lifting mechanism of the extrusion device is turned on (not shown in Figure 1) and crystallization begins. At the same time, along with the main products , the shape of which is determined by the main forming agents, a single-crystal reflective screen grows, the shape of which is specified by the additional shape-forming 5 °. The reflective screen increases the temperature of the inner wall of the product, aligns it with the cross section of the product, thereby improving the quality of the product by reducing thermoelastic stresses, increasing the uniformity of the crystal structure, reducing the difference in tubular products ..

The cultivation and cooling of the grown crystals is carried out in a known manner.

Example K, Growing of three single-crystal cylindrical corundum pipes with a diameter of 8.8 mm with a wall thickness of 1 mm, a length of 980 mm (installation option of the former FIGS 3) with

Growth was carried out on a Crystal-bean plant from a molybdenum crucible with a diameter of 80 mm and a height of 100 mm. The crucible radial temperature difference was 25 ° C.

Alumina was charged into the crucible in the form of waste from Verneuil

The temperature of the crucible was adjusted to 2050 ° C and, after the raw materials were melted, a seed crystal was fed to the former. The height difference between the former was 0.25 mm, 0.01 the numerical value of the radial temperature gradient. For clear etching, the seed crystal was melted by 0.5 mm. The distance between the outer surface of the main shapers and the surface of the additional shaper was 5 mm, and the perimeter of the female surface was 0.6 perimeters of the main shaper in horizontal section and was equal to Tb, mm.

After seeding, cultivation was carried out in a known manner.

The table shows comparable data on the quality of grown single-crystal products from corundum using the proposed device and the prototype device

1 s Residual

voltage

kg / mm2

2nd Density of single dislocations, CM2

3s, difference, mm

 Power consumption, kW

42

5.100, 2

thirty

2,8

5 10

0.05

27

An analysis of the data in the table indicates that the distinguishing features of the proposed technical solution ensure the achievement of the goal - improving product quality, residual stresses less than / vB 1.5 times, dislocation density 2-5 times, difference 3 times

In addition, the proposed device provides a reduction in consumption 51

power and increases the inertia of the entire system, which increases its stability under random disturbances (changes in temperature, growing speed, etc.)

Claims (1)

The claims A device for group growing of shaped crystals, including a melt crucible with a lid mounted on it, in which the capillary system and the main formers are fixed, placed, .PG..b symmetrically to the axis of the crucible at the end of the capillary system, characterized in that, in order to improve the quality of the crystals by reducing the asymmetry of the thermal field, the device is equipped with an additional die, installed along the axis of the crucible with a gap with respect to 1Q of the main formers, repeating their contour the outer surface and having a perimeter in horizontal section equal to 0.6-0.7 of the perimeter of the main formers, and a height of 15 smaller than their height /////////// srig FIG. 2 f (j & 3 jigb