| 摘要 |
The process for preparing an electrical contact material for use in medium-size power switches comprises mixing silver powder with cadmium oxide powder or cadmium powder, whereupon the mixed powders are compacted at approximately 800 kp/cm<2>, and the compact is heated in a reducing atmosphere to obtain a porous alloy of cadmium in silver, without melting the compacted components. The reduced compact is then heated in an oxidising atmosphere in order to reoxidise or oxidise the cadmium in its interior without a melting process. Alternatively, other metals, for example copper instead of silver, can be used in this process. It is also possible to admix an oxide of a third metal, for example lithium or another alkali metal in powdered form. A fourth metal can be added to achieve other desired properties of the material. The contacts are stamped, or are punched from the composite material and treated by further metallurgical techniques such as sintering or rolling, in order to prepare the final contact material. |
