MONOCRYSTAL GROWING BY CRUCIBLELESS ZONE MELTING AND DEVICE TO THIS END Russian patent published in 2014 - IPC C30B13/00 C30B13/30 

FIELD: metallurgy.

SUBSTANCE: proposed method comprises crystal seeding from fused zone, curing for preset time and drawing the monocrystal for seeding from fused zone at temperature gradient. Here, fused zone central symmetric part diameter is controlled. Note also that crystallisation front diameter is selected with preset correction to allow for tolerable deviation of grown monocrystal diameter from preset magnitude. Said magnitude is kept constant during the entire growing process by adjusting the said fused zone central symmetric part diameter owing, in particular, to variation of growth chamber top rod displacement rod. This method is implemented with the help of device including growth chamber 3 with top and bottom rods, video camera 1 fitted in port 2 of growth chamber 3. Video camera output is connected via signal processing unit 4 to control signal generator 5 with its output connected with rod displacement rate ACS input 6, ACS being connected to rod displacement drive 7. Besides it comprises stroboscope 8 arranged ahead of port 2 of growth chamber 3 and synchroniser 9 connected with inputs of stroboscope 8 synchronisation and video camera 1. Signal processing unit 4 comprises processor 10 with image frame isolation module 11, image outline isolation module 12, fused zone central symmetric part diameter calculation module 13 and crystallisation front diameter calculation module 14. Note here that processor 10 is connected with synchroniser 9. Output of video camera 1 is connected to image frame isolation module 11 connected via image outline isolation module 12 to inputs of crystallisation front diameter calculation module 14 and fused zone central symmetric part diameter calculation module 13. Outputs of the latter are connected to first and second averaging filters 15, 16. Control signal generator 5 is composed by two-stage proportional-integration-differentiation controller. Note here that inputs of controller first stage 17 allowing for actual monocrystal crystallisation front are connected with output of the first averaging filter 15 and correction setting module 18. Inputs of the controller second stage 19 allowing for actual monocrystal crystallisation front are connected with controller first stage 17 output and output of second averaging filter 16. Controller second stage 19 output is connected to ACS input.

EFFECT: higher precision of monocrystal diameter measurement and adjustment, stable operation.

3 cl, 2 dwg, 1 tbl