Method of growing mono crystalline tubular bodies from the melt

• US 3,915,662 A
• Filed: 08/15/1973
• Issued: 10/28/1975
• Est. Priority Date: 05/19/1971
• Status: Expired due to Term

• Current Assignee: Saphikon, Inc. (Compagnie de Saint-Gobain SA)
• Original Assignee: Charles J. Cronan, Harold E. Labelle
• Inventors: Labelle, Harold E., Cronan, Charles J.
• Primary Examiner(s): Yudkoff, Norman
• Assistant Examiner(s): Sanders, D.
• Application Number:
  US05/388,597
• Time in Patent Office: 804 Days
• Field of Search: 23/31SP,273SP 264/164
• US Class Current: 117/25
• CPC Class Codes: C30B 15/00 Single-crystal growth by pulling from a melt, e.g. Czochralski method under a protective fluid C30B27/00
• CPC Class Codes: C30B 15/34 Edge-defined film-fed crystal-growth using dies or slits
• CPC Class Codes: C30B 29/60 characterised by shape

Abstract

The invention is a method of growing a monocrystalline extension such as an end wall or flange onto the end of a monocrystalline tube. Typically the tube is made of alumina.

Claims

1. METHOD OF PROVIDING AN INTEGRAL LATERALLY-EXTENDING MONOCRYSTALLINE EXTENSION ON A MONOCRYSTALLINE TUBE WHERE BOTH SAID EXTENSION AND TUBE ARE FORMED OF A CONGRUENTLY MELTING MATERIAL COMPRISING PROVIDING A DIE ASSEMBLY HAVING AN END SURFACE THAT IS LARGER IN AT LEAST ONE DIRECTION THAN A CORRESPONDING DIMENSION OF SAID TUBE AND A CAPILLARY THAT EXTENDS DOWN FROM SAID END SURFACE, FILLING SAID CAPILLARY WITH A MELT OF SAID MATERIAL CONTACTING SAID END SURFACE WITH AN END OF SAID TUBE WHILE MAINTAINING SAID END SURFACE AT A TEMPERATURE AT WHICH THE END OF SAID TUBE WILL MELT AND FORM A FILM ON SAID SURFACE, MELTING ENOUGH OF SAID TUBE END TO FORM A FILM ON SAID SURFACE THAT CONNECTS WITH THE MELT IN SAID CAPILLARY, PULLING SAID TUBE UP AWAY FROM SAID SURFACE AT A RATE AT WHICH SAID FILM WILL SPREAD OVER SAID ENTIRE END SURFACE AND CONTROLLING THE TEMPERATURE OF SAID FILM SO THAT CRYSTAL GROWTH WILL OCCUR ON SAID TUBE AT ITS INTERFACE WITH SAID FILM SIMULTANEOUSLY SUPPLYING ADDITIONAL MELT TO SAID FILM VIA SAID CAPILLARY TO REPLENISH THE MELT CONSUMED BY SAID CRYSTAL GROWTH AND TERMINATING CRYSTAL GROWTH AFTER A DESIRED AMOUNT OF CRYSTAL GROWTH CONFORMING IN CROSS SECTION TO SUBSTANTIALLY THE FULL AREA OF SAID END SURFACE HAS OCCURED ON SAID TUBE.

2. Method according to claim 1 wherein said end surface is annular and the said one end of said tube has substantially the same internal diameter and a different external diameter than said end surface.

3. Method according to claim 1 wherein said end surface is annular and the said one end of said tube has substantially the same external diameter and a different internal diameter than said end surface.

4. Method according to claim 1 wherein said end surface is annular and the said one end of said tube has a smaller external diameter and a larger internal diameter than said end surface.

5. Method according to claim 1 wherein said end surface is concave.

6. Method according to claim 1 wherein said tube is pulled at a rate in the order of 0.1-0.2 inch per minute.

7. Method according to claim 1 wherein said end surface has a single perimeter corresponding in configuration to the outer perimeter of the end of said tube, whereby said crystal growth forms a continuous end wall on said tube.

8. Method according to claim 1 wherein said tube is pulled at one selected rate until said film has spread across the full expanse of said end surface, and thereafter is pulled at a faster rate.

9. Method according to claim 1 wherein said end surface has a single perimeter and is concave and said film spreads out to all points on said end surface within said perimeter as said tube is being pulled and crystal growth occurs on said tube.

10. Method of providing an integral lateral extension on a monocrystalline tube where both said tube and extension are formed of a congruently melting material comprising:

providing a die having a generally horizontal end surface and at least one capillary that extends down from said end surface;

filling said capillary with a melt of said material and maintaining said end surface at a temperature above the melting point of said material;

providing a monocrystalline tube of said material;

positioning said tube above said die and bringing one end of said tube into contact with said end surface long enough for a portion of said tube to melt and form a film on said end surface that connects with the melt in said capillary, thereafter pulling said tube away from said end surface and simultaneously spreading said film over the full expanse of said end surface while controlling the temperature at the interface of said tube and film so that crystal growth will occur on said tube to the full area of said surface; and

feeding additional melt to said capillary and via said capillary to said film as said tube is being pulled so as to make-up for the material consumed by said crystal growth.