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Powder feeder for crystals of large diameter grown by the verneuil technique
Author(s) -
Falckenberg R.
Publication year - 1978
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.19780130618
Subject(s) - sieve (category theory) , materials science , spinel , sapphire , volumetric flow rate , composite material , grain size , fusion , mineralogy , metallurgy , optics , chemistry , mechanics , laser , physics , mathematics , combinatorics , linguistics , philosophy
To grow crystals of large diameter ( ≈ 50 mm) by the flame fusion process it is necessary to feed powder with a flow rate of ≈ 2 g/min into the gas stream, the grain size being as small as possible. The properties of vertically and horizontally excitated sieves are compared. A sieve arrangement with horizontal and vertical vibration is described, which at a mesh width of 90 μm has a powder flow of up to 5 g/min. The long range constancy was within ± 8%. Sieves with a mesh width < 90 μm can be used if an ultrasonic disintegrator is mounted above the feeder sieve. Sapphire and Mg–Al spinel crystals up to 65 mm in diameter could be grown.