| Molybdenum (ELKON® 100M) is a refractory metal that resembles tungsten in many respects. Its hardness, melting, and boiling temperatures are only slightly lower than those of tungsten are. The electrical and thermal conductivity of the two metals is essentially the same. It is fabricated into electrical contacts by slicing discs from rods and brazing them to nickel-plated steel backings, which may be in the form of rivets, screws, or stampings. In atmospheres of inert gasses or vacuum, molybdenum contacts can handle currents of several amperes. Here it has good resistance to welding and electrical erosion because of its refractory metal characteristics. It is readily wet by mercury to form a low resistance contact and is used extensively in mercury switches. It does not contaminate the mercury because it does not react chemically with it. Molybdenum oxidizes more readily than tungsten and, therefore, is seldom used in air applications. If used in air, it is generally limited to 1 ampere and several hundred volts. In certain vibrating contact applications, low mass contacts are desirable, and molybdenum is selected because of its low density. Because of its low expansion characteristic, it is used in non-contact applications such as bases for semiconductor devices. It is also used for faces on resistance welding electrodes. Information provided by NAECO, LLC. |
