| 摘要 |
1459321 Verneiul crystal growing SIEMENS AG 4 April 1974 [16 May 1973] 14932/74 Heading BIS Crystals are manufactured by the Verneiul process by producing a melt at the upper end of a seed crystal by the application of a flame thereto, gradually retracting the crystal from the flame so that material crystallises from the melt onto the crystal at the solidliquid interface, and simultaneously feeding material to form the crystal in powder form from an outlet at the lower end of a reservoir for the crystal powder to the upper surface of the melt, the flame being produced by the interaction of reactive gases directed down towards the melt from the tip of the burner, wherein the powder leaving the reservoir outlet passes down through a vertical passage in the burner to the tip thereof, and wherein one stream of gas is fed through the reservoir outlet and the other stream is fed by a route outside the reservoir in such a manner that when the two streams meet the resultant gas stream has substantially no velocity components in directions perpendicular to the axis of the flow passage whereby no vacuum is produced in the lower part of the reservoir. As shown in Fig. 1 suitable apparatus comprises a powder reservoir 1 containing a screen like partition 4 to support the powdered material 3 required to form the crystal, a gas supply pipe 8 and coaxially with the reservoir a flow passage 9 for a further stream of this first gas passing through the pipe 8. Both gas streams unite near the outlet 6 for the powder from the reservoir and are led down to the burner 12 which is provided with a passage 11 carrying the second gas which reacts with the first gas to form a flame (e.g. oxy-hydrogen). In order to supply the powder 3 continuously the reservoir is vibrated by mechanism 20. |
