公开(公告)号：EP1499842B1

公开(公告)日：2011-08-17

申请号：EP03718211.0

申请日：2003-04-03

申请人： GrafTech International Holdings Inc.

发明人： MILLER, Douglas, J. ,  RUOFF, Werner, H. ,  INTERMILL, Allan, W. ,  THOMAN, Thomas, R. ,  SHAO, Richard, L. ,  STRONG, Stephen, L.

IPC分类号： D01F9/32 ,  F27B14/06

CPC分类号： F27B14/061 ,  D01F9/322 ,  F27D2009/0018 ,  F27D2099/002

摘要： An induction furnace capable of operation at temperatures of over 3100°C has a cooling assembly (60), which is selectively mounted to an upper end of the furnace wall (76). The cooling assembly includes a dome (62), which is actively cooled by cooling water coils (68). During the cool­down portion of a furnace run, cooling initially proceeds naturally, by conduction of heat away from the hot zone through a furnace insulation layer (58). Once the temperature within the furnace hot zone (20) reaches about 1500°C, a lifting mechanism (80), mounted to the dome, raises a cap (16) of the furnace slightly, allowing hot gases from the hot zone to mix with cooler gas in the dome. This speeds up cooling of the hot zone, reducing cool-down times significantly, without the need for encumbering the furnace itself with valves or other complex cooling mechanisms which have to be replaced periodically. The life of a graphite furnace susceptor (10) at the high operating temperature is increased by surrounding the susceptor with a barrier layer (40) of flexible graphite, which inhibits evaporation of the graphite. Additionally, witness disks (154), placed within the susceptor, provide an accurate temperature profile of the hot zone.