| 摘要 |
<p>Elements are made of an alloy of a metal which is a good conductor, e.g. Cu, Ag or Au, with a small amt. of a substance more readily oxidised than the metal; and the contact surface of the elements is heated to produce internal oxidn. Heating is pref. limited so the thickness of the layer of internal oxidn. does not exceed a few hundred microns. Heating is pref. in an oxidant gas, e.g. air at 800 degrees C., or the contact surface can be covered with an oxide thermally decomposed in presence of the base metal to form O2 diffusing into the latter. Pref. elements consist of copper used with copper oxide or nickel oxide, with heating to 1000 degrees C so O2 diffuses into the Cu. Alternatively, the substance more readily oxidised is pref. Be, Cr, Co, Ni, Si, Be-Co, or Ni-Si; when the base metal is Ag or Au, Cu may be used as the addn. Contact elements have good conductivity and do not undergo seizure or microwelding. They are suitable for contacts moving at slow speeds and/or for intermittent use.</p> |
