| 摘要 |
<p>PURPOSE:To prevent the occurrence of contraction and cracks of sintered body in a soldering process by filling alumina powder which is relatively small in size with a narrow range of size distribution, into the insides of heaters and spaces among heater wires so as to be sintered, and concurrently filling alumina powder which is in a wide range of size distribution, into the spaces of the heaters so as to be sintered. CONSTITUTION:Alumina powder which is relatively small in size with a small range of size distribution, is filled in the insides of heaters 3 and spaces 5 among heater wires which are arranged within a cathode support cylinder 2, and alumina powder which is in a wide range of size distribution same as that of a former one, is filled in the other spaces 4, and the aforesaid alumina powder is sintered thereafter. By this constitution, sintered alumina is hardly contracted or cracked even if it is subjected to high temperature up to about 2000 deg.C after sintering, and the circumferential section of a cathode can thereby be soldered.</p> |
