| 摘要 |
<p>PURPOSE:To manufacture an impregnation type cathode excellent in useful life characteristics and stability besides ample distinctive qualities, by cladding the surface of a tungsten grain with such metallic elements as osmium, iridium and ruthenium of its simple substance or their alloy and sintering this metal-clad tungsten gain, thus forming a sintered base body. CONSTITUTION:Iridium-carbonyl is dissolved in ethyl alcohol, by way of example, and a tungsten grain powder of about 5mum in average grain diameter is mixed, while an iridium metallic film of about 0.5mum in thickness is deposit- metallized on the surface of the tungsten grain after being heated with about 200 deg.C in a current of hydrogen. Afterward, it is formed with the same process as does the following conventional technique. Powder of the said iridium-clad tungsten grain is sintered with a temperature of about 2,200 deg.C in an ambience of hydrogen and it is made into something a bar of about 20% in porosity. Then, this bar's porous part is impregnated with copper so as to have its machining facilitated and then it is machined by a lathe into a circular plate or disc of 35mm. in diameter and 3mm. in thickness, for example.</p> |
